Abstract
Background
Herbs and dietary supplement (HDS) use has become increasingly used among the Thai population due to greater health awareness and easier product access. However, research on adverse events from HDS and information needs relating to HDS among the Thai population is limited. This study aims to explore use, adverse experiences, self-assessed knowledge and perspectives on HDS among the general public in Thailand.
Methods
A cross-sectional self-administered survey in the general public conducted in 6 public areas in a large city of northeastern Thailand, over 5-month period. It explored experiences relating to use and adverse effects of HDS. Knowledge and information needs relating to HDS were self-assessed by using a visual analog scale and closed questions. The perspectives on HDS were determined using the 5 point-Likert scales for degree of agreement. Participants were selected by purposive sampling.
Results
Of the 1,064 questionnaires distributed, 540 (51.0%) respondents reported using herbal and dietary supplements (HDS). Among them, 363 (67.2%) used herbs, and 423 (78.3%) used dietary supplements, with 40.3% using these products infrequently in the past six months. Common herbs included andrographis (25.3%), turmeric (21.2%), and senna (6.9%), while vitamin C (41.8%), collagen (11.8%), and vitamin B complex (9.0%) were the most frequently used dietary supplements. Adverse effects were reported by 42 respondents, primarily associated with turmeric (25.0%) and vitamin C (31.8%), with most rating the severity as mild (76.2%). Self-assessed knowledge about HDS use and adverse effects was moderate, with a significant demand for information on interactions with medications (59.3%), adverse effects (57.0%), and actions to take if adverse effects occur (52.8%). Higher education levels correlated with increased in knowledge about HDS use and adverse effects (p = 0.007 and p = 0.001, respectively).
Conclusions
Approximately half of the general public in Thailand use HDS, with a small number of reporting adverse events, primarily mild gastrointestinal effects. The public has a moderate level of knowledge about the use and adverse effects of HDS, but there is a need for improved safety knowledge relating to HDS.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12906-025-04971-2.
Keywords: Herbs, Dietary supplements, General public, Adverse effects, Self-assessed knowledge, Perspectives
Background
Herbs, including medicinal plants, herbal materials, and finished herbal products, contain phytochemicals and are popular in traditional use or alternative therapy for preventing, relieving, treating, and controlling some chronic diseases [1–3]. Defined by the US Dietary Supplements Health and Education Act (DSHEA), dietary supplements include vitamins, minerals, herbs, botanicals, amino acids, and other substances intended to supplement the diet by increasing overall dietary intake [4]. Several studies in the community and general population from various countries have reported a high prevalence of herbal and dietary supplement (HDS) use for multiple reasons, such as illness treatment, health promotion, weight loss, and beauty purposes [5–10].
The perceived benefits of HDS, such as preventing health problems or filling nutrient gaps, motivate people to continue or start using them [5, 11]. Additionally, HDS are considered easily available and more cost-effective than conventional medications [12]. In Thailand, the master plan on Thai herbal development (2017–2021), implemented by the Ministry of Public Health, has launched to promote the use of herbal medicine products and enhance knowledge of Thai herbal products [13]. In 2018, seventy-four herbal remedies were included in the National List of Essential Medicines [14]. Many hospitals in Thailand also provide Thai traditional medicine services, which include prescribing herbal medicines, indicating the growing acceptance and use of these products within the healthcare system [15].
Despite their popularity and official endorsement, the safety of HDS use remains a critical concern. The use of HDS in patients with chronic conditions may lead to unfavorable therapeutic outcomes [16]. A study in the United States from 2004 to 2013 reported that dietary supplements were associated with over 23,000 annual emergency department visits, with 65.9% related to herbal or complementary products and the remainder to micronutrients [17]. The World Health Organization (WHO) VigiBase found 5,761 adverse cutaneous reactions associated with traditional medicines [18]. In Thailand, VigiBase data showed 593 reports involving 1,868 adverse events from herbal product use [19]. These adverse events were reported through a spontaneous reporting system, allowing healthcare professionals to submit reports. Studies relating to adverse events from HDS among Thai population are relatively limited, with previous studies in Thailand focusing on the prevalence and knowledge of HDS use among the general public [5, 20–22]. However, there is a lack of research on the experiences of adverse effects from HDS use and the information needs of the general public. This study therefore aimed to explore the use and adverse effects of HDS, as well as the self-assessed knowledge and perspectives on HDS among the Thai general public.
Methods
Study design and setting
This was a cross-sectional survey using a self-completed questionnaire performed in community settings of Khon Kaen province, Thailand. This study was carried out over 5-month period.
Participants and sample size
Eligible participants were aged above 18 years old, and were living in Mueang District, Khon Kaen province, and had ever used HDS. If they had experienced more than one adverse symptom related to both herbs and dietary supplements, the most recent symptom was chosen for the questionnaire. Participants who could not read Thai, communicate with the researcher, did not voluntarily agree to complete the questionnaire, or had previously completed a related questionnaire were excluded from the study. The sample size was calculated using Yamane’s equation with a 5% margin of error. Based on the 2016 population data showing 120,045 residents in Mueang District and accounting for a 30% rate of invalid responses, the required sample size was 540 participants.
Questionnaire development, testing and distribution
The survey questionnaire consisted of three sections:
Section 1: Demographic characteristics including gender, age, occupation, education level, income, medical conditions, experience of drug allergies.
Section 2: Use of the HDS including sources, indications, and frequency of using the HDS.
Section 3: Experience of adverse effects from HDS including description, duration, and severity of recent adverse effects. Severity was categorized as mild (tolerable adverse effects), moderate (adverse effects that disturbed daily activities), and severe (adverse effects that prevented daily activities). Data were collected using both closed-ended and open-ended questions.
Section 4: Self-assessed knowledge and perspectives on HDS. A self-reported visual analog scale (VAS), scoring from 0 (least knowledge level) to 10 (most knowledge level) was used to assess the self-assessed knowledge about use and adverse effects of HDS. Closed questions were used to assess information needs relating to HDS. Five-point Likert scales with responses ranging from strongly disagree (1) to strongly agree (5) were used to assess the 8 statements of perspectives on HDS.
The questionnaires were validated for content validity by three experts: one pharmacist who had expertise in HDS and two pharmacists who had expertise in adverse reactions of healthcare products, using the index of item objective congruence (IOC) technique. All questions achieved content validity with an IOC > 0.5. Questions with an IOC < 0.5 were revised based on expert feedback. A pilot test with 20 members of the general public was conducted to ensure comprehension and ease of reading.
The final questionnaire was distributed using purposive sampling in six types of public areas in Khon Kaen province, Thailand: a university campus, four public parks, and a large market. For respondents who had visual problems, researchers provided assistance by reading the questionnaire without offering additional explanations.
Data analysis
Simple frequencies were used to report general information including gender, education level, occupation, income, previous underlying diseases and drug/herbs allergy, experience and adverse effects from the use of HDS. Frequencies, mean and standard deviation (S.D.) were used to report knowledge and perspectives on the use and adverse effects of HDS. Level of knowledge was classified as low (score 0.0-3.3), moderate (score 3.3–6.6) and high (score 6.7–10.0). Negative questions inquired about perspectives were transformed into positive statements before computing the scores. Pearson chi-square and Fisher’s exact test were used to compare demographic characteristics of respondents using HDS. Multiple logistic regression was used to determine factors associated with self-assessed knowledge about use and adverse effects of HDS. P-value less than 0.05 was accepted as indicating significant differences between sub-groups.
Results
Demographic data of respondents
Of the total 1,064 questionnaires distributed, 540 (51.0%) were reported use of HDS. The majority of those respondents were female (n = 379, 70.2%) with an average age of 41.7 ± 29.88, and had bachelor’s degree and higher education (n = 390, 72.2%). Almost one-fourth of respondents had one or more underlying diseases (n = 134, 24.8%). Allergic rhinitis (n = 43, 8.0%), hypertension (n = 38, 7.0%), and diabetes (n = 21, 3.9%) were the most reported diseases. The characteristics of 540 respondents who reported use of HDS are shown in Table 1.
Table 1.
Characteristics of respondents who reported use of herbal and dietary supplement
| Characteristics | Herbal n = 262 (%) |
Dietary supplement n = 278 (%) | Total n = 540 |
|---|---|---|---|
| Gender | |||
| • Male | 99 (37.8) | 62 (22.3) | 161 (29.8) |
| • Female | 163 (62.2) | 216 (77.7) | 379 (70.2) |
| Age group (years) | |||
| • 18–30 | 101 (38.5) | 193 (69.4) | 294 (54.5) |
| • 31–60 | 111 (42.4) | 64 (23.0) | 175 (32.4) |
| • More than 60 | 50 (19.1) | 21 (7.6) | 71 (13.1) |
| Education levels | |||
| • Primary school | 36 (13.7) | 7 (2.5) | 43 (8.0) |
| • Junior high school | 18 (6.9) | 6 (2.2) | 24 (4.4) |
| • High school | 23 (8.8) | 20 (7.2) | 43 (8.0) |
| • Diploma | 19 (7.3) | 20 (7.2) | 39 (7.2) |
| • Bachelor’s degree | 141 (53.8) | 193 (69.4) | 334 (61.9) |
| • Master’s degree | 19 (7.3) | 25 (9.0) | 44 (8.1) |
| • Doctoral Degree | 5 (1.9) | 7 (2.5) | 12 (2.2) |
| • Others | 1 (0.4) | 0 (0.0) | 1 (0.2) |
| Occupations | |||
| • None | 42 (16) | 20 (7.2) | 62 (11.5) |
| • College students | 78 (29.8) | 164 (59.0) | 242 (44.8) |
| • Farmers | 3 (1.1) | 0 (0.0) | 3 (0.6) |
| • Private company employee | 16 (6.1) | 14 (5.0) | 30 (5.6) |
| • Business owner | 38 (14.5) | 28 (10.1) | 66 (12.2) |
| • Freelance | 21 (8.0) | 7 (2.5) | 28 (5.2) |
| • Government employee | 43 (16.4) | 28 (10.1) | 71 (13.1) |
| • Others | 21 (8.0) | 17 (6.1 | 38 (7.0) |
| Income | |||
| • Lower than 10,000 baht | 134 (51.1) | 152 (54.7) | 286 (53.0) |
| • 10,001–20,000 baht | 60 (22.9) | 71 (25.5) | 131 (24.3) |
| • 20,010–30,000 baht | 25 (9.5) | 20 (7.2) | 45 (8.3) |
| • Higher than 30,000 baht | 43 (16.4) | 35 (12.6) | 78 (14.4) |
| Underlying disease | |||
| • Yes* | 80 (30.5) | 54 (19.4) | 134 (24.8) |
| • No | 182 (69.5) | 224 (80.6) | 406 (75.2) |
| Drug allergy | |||
| • Yes | 19 (7.3) | 20 (7.2) | 39 (7.2) |
| • No | 243 (92.7) | 258 (92.8) | 501 (92.8) |
*Underlying diseases: allergic rhinitis (n = 43), hypertension (n = 38), diabetes (n = 21), peptic ulcer disease (n = 16), asthma (n = 7), dyslipidemia (n = 7), thyroid disease (n = 5), osteoarthritis (n = 3), heart diseases (n = 3), Meniere’s Disease (n = 3), anemia (n = 2), not specified (n = 11)
Use of herbal and dietary supplements
Of the total 540 respondents, 363 (67.2%) reported using herbs and 423 (78.3%) reported using dietary supplements. The majority of respondents reported using HDS only once or less in the past 6 months (n = 232, 43.0%). Additionally, they reported a moderate level of knowledge regarding the use of these supplements (n = 241, 44.6%). The major source for purchasing HDS was drugstore (n = 256, 38.15%), followed by general/department store (n = 159, 23.7%), and herbs or dietary supplement shop (n = 72, 10.7%). Andrographis, turmeric, and senna were the most popular herbs, while vitamin C, collagen, and vitamin B complex were the most popular dietary supplements among respondents (Table 2).
Table 2.
Indications of herbal and dietary supplements use
| Rank of herbal and dietary supplements use | Herbal and dietary supplements | Number (%) of herbal and dietary supplements | Indications (n) |
|---|---|---|---|
| Herbs ( n = 363) | |||
| 1 | Andrographis (Andrographis paniculata) | 92 (25.3) | Common cold (50), sore throat (25) |
| 2 | Turmeric (Curcuma longa) | 77 (21.2) | Gastritis (16), flatulence (18), body scrubbing (15) |
| 3 | Senna (Cassia angustifolia Vahl) | 25 (6.9) | Constipation (25) |
| 4 | Aloe vera (Aloe barbadensis) | 14 (3.9) | Skin soothing (2), burn wound (2) |
| Moringa oleifera | 14 (3.9) | Constipation (1), decrease blood sugar (1) | |
| 5 | Curcuma comosa Roxb. | 10 (2.8) | Abnormal symptoms of the uterus (3), uterine discomfort (2) |
| 6 | Indian gooseberry (Phyllanthus emblica L.) | 9 (2.5) | Cough (1), sore throat (1) |
| 7 | Shatavari (Asparagus racemosus Willd.) | 8 (2.2) | Abnormal symptoms of the uterus (3), uterine discomfort (2) |
| Ginseng (Panax ginseng) | 8 (2.2) | Boost energy (6) | |
| 8 | Finger root (Boesenbergia rotunda) | 7 (1.9) | Improving health (3) |
| 9 | Tiliacora triandra | 6 (1.7) | Fever (2) |
| 10 | Ginger (Zingiber officinale) | 5 (1.4) | Flatulence (1), sore throat (1) |
| Centella asiatica | 5 (1.4) | Skin soothing (1) | |
| 11 | Phlai (Zingiber montanum) | 4 (1.1) | Pain relief (2) |
| 12 | Houttuynia cordata | 3 (0.8) | Improving health (2) |
| Phyllanthus niruri | 3 (0.8) | Reducing blood sugar (2), reducing blood cholesterol (1) | |
| Garlic (Allium sativum) | 3 (0.8) | Reducing blood pressure (2), common cold (1) | |
| 13 | Helianthus tuberosus | 2 (0.6) | Blood nourishment (2) |
| Safflower (Carthamus tinctorius) | 2 (0.6) | Reducing blood cholesterol (1), reducing heart disease risk (1) | |
| Triphala* | 2 (0.6) | Allergic rhinitis (2) | |
| Gingko (Ginkgo biloba) | 2 (0.6) | Improving brain function (2) | |
| Caesalpinia sappan | 2 (0.6) | Improving health (2) | |
| Thunbergia laurifolia | 2 (0.6) | Fever (1), detox (1) | |
| 14 | Others | 58 (16.0) | - |
| Dietary supplements, n = 423 | |||
| 1 | Vitamin C | 177 (41.8) | Skin nourishment (43), improving health (41), preventing common colds (29) |
| 2 | Collagen | 50 (11.8) | Skin nourishment (29), collagen supplement (4) |
| 3 | Vitamin B complex | 38 (9.0) | Improving health (20), improving nerve function (11), improving brain function (6) |
| Fish oil | 21 (5.0) | Improving brain function (9), improving health (7) | |
| 4 | Calcium | 20 (4.7) | bone strengthening (14), calcium supplement (3) |
| 5 | Protein extract | 17 (4.0) | Protein supplement (11) |
| 6 | Multivitamin | 16 (3.8) | Improving health (8), vitamin supplement (3) |
| 7 | Glutathione | 13 (3.1) | Skin whitening (8), skin nourishment (2) |
| 8 | Zinc | 12 (2.8) | Skin and hair nourishment (4), reducing oily face (2) |
| 9 | Royal Jelly | 8 (1.9) | Weight loss (4), skin nourishment (3) |
| Lingzhi (Ganoderma lucidum) extract | 8 (1.9) | Improving health (4), sleep promoting (2) | |
| 10 | Astaxanthin | 4 (0.9) | Skin nourishment (3) |
| 11 | Chlorophyll extract | 3 (0.7) | Improving health (3) |
| 12 | Centella asiatica extract | 2 (0.5) | Improving brain function (2) |
| Grape seed extract | 2 (0.5) | Skin nourishment (2) | |
| L-carnitine | 2 (0.5) | Metabolism boosting (2) | |
| Vitamin A | 2 (0.5) | Eye care (2) | |
| Ferrous | 2 (0.5) | Blood nourishment (2) | |
| 13 | Others | 26 (6.1) | - |
* Poly-herbal preparation, which is composed of Phyllanthus emblica, Terminalia chebula, and Terminalia bellirica
Experiences of adverse effects from herbal and dietary supplement use
Of the total respondents, 42 (7.8% of HDS users) reported one or more adverse effects from HDS. Twenty of respondents (3.7%) indicated they had experienced an adverse effect from using herbs. Of the total 20 respondents, turmeric was the herb that respondent reported as causing the most adverse effects (n = 5, 25.0%) including nausea, rash, skin peeling and abdominal pain, followed by gastrointestinal irritation from using senna (n = 3, 15.0%), and vomiting and rash from using Moringa oleifera (n = 3, 15.0%). Twenty-two (4.1%) experienced an adverse effect from using dietary supplements. Of the 22 respondents, vitamin C was the dietary product that respondents reported as causing the most adverse effects (n = 7, 31.8%) which were dark urine, diarrhea, abdominal pain, nausea, and mouth sore, followed by vitamin B complex (n = 3, 13.6%), and collagen (n = 2, 9.1%) (Table 3).
Table 3.
Self-reported adverse effects from herbal and dietary supplement
| Herbal and dietary supplement | Number of respondents (%) | Adverse symptoms reported (n) |
|---|---|---|
| Herbs, n = 20 | ||
| Turmeric (Curcuma longa) | 5 (25.0) | Nausea (1), rash (2), peeling skin (1), abdominal pain (1) |
| Senna (Cassia angustifolia Vahl) | 3 (15.0) | Gastrointestinal discomfort (3) |
| Moringa oleifera | 3 (15.0) | Vomiting (2), rash (1) |
| Brinjal | 2 (10.0) | Throat irritation (2) |
| Curcuma comosa Roxb. | 1 (5.0) | Vaginal bleeding (1) |
| Indian gooseberry (Phyllanthus emblica L.) | 1 (5.0) | Excessive sputum (1) |
| Ginseng (Panax ginseng) | 1 (5.0) | Tachycardia (1) |
| Maerua siamensis | 1 (5.0) | Proteinuria (1) |
| Butea superba | 1 (5.0) | Tongue ulcer (1) |
| Tiliacora triandra | 1 (5.0) | Fatigue (1) |
| Andrographis (Andrographis paniculata) | 1 (5.0) | Arrhythmia (1) |
| Dietary supplements, n = 22 | ||
| Vitamin C | 7 (31.8) | Dark urine (3), Diarrhea (1), abdominal pain (1), nausea (1), mouth ulcers (1) |
| Vitamin B complex | 3 (13.6) | Dark urine (2), Nausea (1) |
| Collagen | 2 (9.1) | Dizziness (1), Amenorrhea (1) |
| Reishi | 2 (9.1) | Polyuria (1), Rash (1) |
| Protein extract | 2 (9.1) | Diarrhea (1), vomiting (1) |
| Astaxanthine | 1 (4.5) | Bleeding (1) |
| L-carnitine | 1 (4.5) | Arrhythmia (1) |
| Ginseng extract | 1 (4.5) | Itchy (1) |
| L-Phenylalanine | 1 (4.5) | Dizziness, rash (1) |
| Mixed fiber powder | 1 (4.5) | Arrhythmia (1) |
| Glutathione | 1 (4.5) | Headache (1) |
Among the 42 respondents who reported adverse symptoms from HDS, the majority of respondents (n = 22, 52.4%) had experienced an adverse effect from HDS use within in past six months, and the remaining more than six months ago. Most respondents indicated the most adverse effects lasted not more than 3 days (n = 22, 52.4%). Approximately three-thirds (n = 31, 73.8%) stopped using the suspected HDS and most of the symptoms were recovered. The majority of respondents (n = 32, 76.2%) reported the perceived severity of their adverse symptoms as mild (n = 32, 76.2%). However, 6 (14.3%) identified as severe. The large majority of respondents (n = 35, 83.3%) had never reported their adverse experiences to the healthcare professionals (Table 4).
Table 4.
Experiences of adverse effects from herbal and dietary supplements
| Experiences of adverse effects | Number of respondents (%) | ||
|---|---|---|---|
| Herbs, n = 20 | Dietary supplements, n = 22 |
Total, n = 42 | |
| Time of last adverse effects | |||
| • ≤ 1 week | 1 (5.0) | 2 (9.1) | 3 (7.1) |
| • > 1 week to 1 month | 3 (15.0) | 4 (18.2) | 7 (16.7) |
| • > 1 to 6 months | 5 (25.0) | 7 (31.8) | 12 (28.6) |
| • > 6 to 12 months | 4 (20.0) | 5 (22.7) | 9 (21.4) |
| • > 1 to 5 years | 4 (20.0) | 2 (9.1) | 6 (14.3) |
| • > 5 years | 3 (15.0) | 2 (9.1) | 5 (11.9) |
| Action after experiencing the adverse effects | |||
| • Stop using the herbs/dietary supplements | 16 (80.0) | 15 (68.2) | 31 (73.8) |
| • Continue using the herbs/dietary supplements | 4 (20.0) | 7 (31.8) | 11 (26.2) |
| Symptoms after discontinuation of the suspected herbs/dietary supplements | |||
| • The symptoms disappeared | 11 (68.8) | 11 (73.3) | 22 (64.6) |
| • The symptom severity decreased | 4 (25.0) | 4 (26.7) | 8 (23.5) |
| • The symptoms were unchanged | 1 (6.2) | 0 (0.0) | 1 (2.9) |
| Severity of the adverse effects | |||
| • Mild | 15 (75.0) | 17 (77.3) | 32 (76.2) |
| • Moderate | 0 (0.0) | 4 (18.2) | 4 (9.5) |
| • Severe | 5 (25.0) | 1 (4.5) | 6 (14.3) |
| Duration of experiencing the adverse effects | |||
| • ≤ 3 days | 10 (50.0) | 12 (54.5) | 22 (52.4) |
| • 4–6 days | 3 (15.0) | 2 (9.1) | 5 (11.9) |
| • > 1 to 4 weeks | 3 (15.0) | 2 (9.1) | 5 (11.9) |
| • > 1 to 3 months | 1 (5.0) | 3 (13.6) | 4 (9.5) |
| • > 3 months | 3 (15.0) | 3 (13.6) | 6 (14.3) |
| Frequency of symptoms reported to healthcare professionals | |||
| • Never | 15 (75.0) | 20 (91.0) | 35 (83.3) |
| • Sometimes | 3 (15.0) | 1 (4.5) | 4 (9.5) |
| • Always | 2 (10.0) | 1 (4.5) | 3 (7.2) |
Self-assessed knowledge, information needs, and perspectives on HDS
The overall mean score of knowledge about use and adverse effects of HDS was 5.19 + 3.39 and 4.22 + 2.79, respectively. The majority of respondents (n = 241, 44.6%) had moderate knowledge regarding the use of HDS. Similarly, a significant portion of respondents (n = 233, 43.1%) also had a moderate knowledge regarding the identification of adverse effects from the use of HDS. The respondents stated that they had received sufficient information regarding indications (n = 471, 87.2%), how to take (n = 432, 80.0%), and names of herbal and dietary supplements (n = 333, 61.7%). Respondents considered information about interaction between HDS and concurrent medications as the most requirement (n = 320, 59.3%), followed by adverse effects (n = 308, 57.0%) and what to do if the adverse effects occur (n = 285, 52.8%) (Table 5). Logistic regression analysis found that education level at higher than bachelor’s degree was associated with high level in knowledge about use and adverse effects of HDS (adjusted odds ratio; aOR = 2.815, p = 0.007, and aOR = 3.883, p = 0.001). Experience of drug allergies was also associated with high level in knowledge about adverse effects of HDS (aOR = 2.521, p = 0.016) (Table 6).
Table 5.
Adequate information received on herbal and dietary supplements, with further information needs
| Contents of information | Adequately received (n, %) | Further information needed (n, %) |
|---|---|---|
| Names of herbal and dietary supplements | 333 (61.7) | 70 (13.0) |
| Contraindications / Precautions | 220 (40.7) | 227 (42.0) |
| Indications | 471 (87.2) | 63 (11.7) |
| Dosage | 293 (54.3) | 113 (20.9) |
| How to take | 432 (80.0) | 57 (10.6) |
| Adverse effects | 132 (24.4) | 308 (57.0) |
| How to assess the adverse effects | 62 (11.5) | 284 (52.6) |
| What to do if the adverse effects occur | 79 (14.6) | 285 (52.8) |
| Interactions with other medicines | 52 (9.6) | 320 (59.3) |
Table 6.
Factors associated with self-assessed knowledge about use and adverse effects of herbal and dietary supplements
| Factors | Number of respondents (%) | Adjusted odds ratio | 95% Confidence interval | p-value | ||
|---|---|---|---|---|---|---|
| Low to moderate knowledge level | High knowledge level | Lower | Upper | |||
| Knowledge about use of HDS | ||||||
| Age groups (years) | ||||||
| • 18–30 | 175 (52.7) | 119 (57.2) | 1 | |||
| • 31–60 | 104 (31.3) | 71 (34.1) | 0.752 | 0.366 | 1.546 | 0.438 |
| • More than 60 | 53 (16.0) | 18 (8.7) | 0.804 | 0.322 | 2.010 | 0.641 |
| Education levels | ||||||
| • Lower than bachelor’s degree | 112 (33.7) | 39 (18.8) | 1 | |||
| • Bachelor’s degree | 196 (59.0) | 137 (65.9) | 1.518 | 0.894 | 2.579 | 0.123 |
| • Higher than bachelor’s degree | 24 (7.2) | 32 (15.4) | 2.815 | 1.327 | 5.969 | 0.007 |
| Income per month | ||||||
| • Lower than 10,000 baht | 192 (57.8) | 94 (45.2) | 1 | |||
| • 10,000–20,000 baht | 78 (23.5) | 53 (25.5) | 1.163 | 0.715 | 1.890 | 0.543 |
| • Higher than 20,000 baht | 62 (18.7) | 61 (29.3) | 1.545 | 0.833 | 2.863 | 0.167 |
| Underlying disease | ||||||
| • No | 244 (73.5) | 162 (77.9) | 1 | |||
| • Yes | 88 (26.5) | 46 (22.1) | 1.005 | 0.634 | 1.594 | 0.982 |
| Drug allergy | ||||||
| • No | 312 (94.0) | 189 (90.9) | 1 | |||
| • Yes | 20 (6.0) | 19 (9.1) | 1.624 | 0.809 | 3.260 | 0.173 |
| Knowledge about adverse effects of HDS | ||||||
| Age groups (years) | ||||||
| • 18–30 | 124 (49.0) | 170 (59.2) | 1 | |||
| • 31–60 | 81 (32.0) | 94 (32.8) | 0.867 | 0.433 | 1.736 | 0.687 |
| • More than 60 | 48 (19.0) | 23 (8.0) | 0.629 | 0.264 | 1.503 | 0.297 |
| Education levels | ||||||
| • Lower than bachelor’s degree | 95 (37.5) | 56 (19.5) | 1 | |||
| • Bachelor’s degree | 146 (57.7) | 187 (65.2) | 1.392 | 0.844 | 2.296 | 0.195 |
| • Higher than bachelor’s degree | 12 (4.7) | 44 (15.3) | 3.883 | 1.730 | 8.717 | 0.001 |
| Income per month | ||||||
| • Lower than 10,000 baht | 145 (57.3) | 141 (49.1) | 1 | |||
| • 10,000–20,000 baht | 62 (24.5) | 69 (24.0) | 1.175 | 0.729 | 1.895 | 0.508 |
| • Higher than 20,000 baht | 46 (18.2) | 77 (26.8) | 1.598 | 0.864 | 2.953 | 0.135 |
| Underlying disease | ||||||
| • No | 177 (70.0) | 229 (79.8) | 1 | |||
| • Yes | 76 (30.0) | 58 (20.2) | 0.732 | 0.466 | 1.150 | 0.176 |
| Drug allergy | ||||||
| • No | 241 (95.3) | 260 (90.6) | 1 | |||
| • Yes | 12 (4.7) | 27 (9.4) | 2.521 | 1.186 | 5.358 | 0.016 |
Abbreviations: HDS, herbal and dietary supplements
Bolded values highlight statistically significant p-value less than 0.05
The majority of respondents agreed with statements such as selecting dietary supplement products that have been certified by the Food and Drug Administration (FDA) (n = 485, 89.8%), expressing the demand of reporting any adverse effects from HDS directly to the FDA or a relevant agency (n = 384, 71.1%), and believing that taking HDS can help treat and prevent diseases more effectively (n = 351, 65.0%). Conversely, most respondents believed that self-purchasing HDS is safe enough (n = 88, 16.3%), their health might get worse if they do not take any HDS (n = 89, 16.5%), and HDS are more effective than conventional medications (n = 107, 19.9%) (Table 7).
Table 7.
Perspectives of respondents towards herbal and dietary supplements
| Statements | Perspectives (number of respondents, %) | Mean ± S.D. | |||||
|---|---|---|---|---|---|---|---|
| Absolutely agree | Agree | Not sure | Disagree | Absolutely disagree | |||
| 1. You prefer self-selection of herbal or dietary supplements over receiving them from healthcare professionals. | 36 (6.7) | 141 (26.1) | 111 (20.6) | 219 (40.6) | 33 (6.1) | 3.13 ± 0.60 | |
| 2. Self-purchasing herbal or dietary supplements is safe enough. | 9 (1.7) | 79 (14.6) | 63 (11.7) | 210 (38.9) | 179 (33.1) | 3.87 ± 0.77 | |
| 3. If you experience any side effects from herbal or dietary supplements, you can assess these occurred side effects. | 17 (3.1) | 172 (31.9) | 275 (50.9) | 64 (11.9) | 12 (2.2) | 3.22 ± 0.70 | |
| 4. You want to report any adverse effects herbal or dietary supplements directly to the FDA or relevant agency. | 314 (58.1) | 70 (13.0) | 124 (23.0) | 27 (5.0) | 5 (0.9) | 4.22 ± 1.19 | |
| 5. You only choose dietary supplement products that have been certified by the FDA. | 324 (60.0) | 161 (29.8) | 43 (8.0) | 9 (1.7) | 3 (0.6) | 4.47 ± 1.27 | |
| 6. Your health might get worse if you do not take any herbal or dietary supplements. | 23 (4.3) | 66 (12.2) | 59 (10.9) | 161 (29.8) | 231 (42.8) | 3.95 ± 0.87 | |
| 7. Some types of herbal and dietary supplements can help treat and prevent diseases more effectively. | 311 (57.6) | 40 (7.4) | 133 (24.6) | 48 (8.9) | 8 (1.5) | 4.11 ± 1.18 | |
| 8. Herbal and dietary supplements are more effective than conventional medications. | 23 (4.3) | 84 (15.6) | 43 (8.0) | 110 (20.4) | 280 (51.9) | 4.00 ± 1.04 | |
Abbreviations: S.D., standard deviation; FDA, Food and Drug Administration
Discussion
Main findings
Approximately two-thirds of our respondents had used HDS, with 40% having used them within the past six months. These findings are similar to a previous survey on dietary supplement consumption in Thailand, which reported a 52% prevalence of HDS use in the past six months [5]. Females were more likely to use HDS than males, which was also found in the previous surveys [5, 7, 21, 23]. Adult working populations showed higher usage of HDS compared to other groups. This differs from some studies that found a positive association between increasing age and HDS usage [6, 23].
Many HDS are easily accessible without prescriptions. Andrographis and turmeric were the most commonly used herbs in this study, similar to previous research in Thailand [5, 20]. Andrographis is promoted for treating sore throat, common cold, and non-infectious diarrhea, while turmeric is recommended for relieving flatulence [24]. Consumers generally perceive herbal products as safe due to their natural origins and long history of use [25, 26]. Some consumers believed that herbs are more effective than conventional medicines and can cure various illnesses [21, 27]. However, turmeric was frequently reported to cause adverse effects, consistent with findings from the Thai Health Product Vigilance Center (HPVC) Database [19, 28]. Skin reactions including maculopapular rash, urticaria, and exfoliative dermatitis were reported as adverse events from taking turmeric-containing products [19, 28]. Among dietary supplements, vitamin C was most commonly reported to cause adverse effects, including dark urine and gastrointestinal effects. Although most vitamins and minerals are generally safe, overdosing can lead to acute and/or chronic toxicity [29]. For example, high-dose vitamin C or ascorbic acid supplement can increase the risk of kidney stones [30].
Consumer-reported adverse events are common with conventional medicines, but the reported incidence of adverse effects from HDS varies between studies. In the Northeast of England, approximately 45% of hospitalized patients who had used HDS in the past 2 years reported an experience of HDS-related adverse events [31], whereas a study in the United Arab Emirates found that only a small percentage of the general public reported side effects or complications from complementary and alternative medicine [32]. Most reported adverse events were mild to moderate and tended to resolve after discontinuation, consistent with the findings of the current study. Another study in India found that approximately 70% of patients could not identify any adverse reactions and were unsure whether these effects were due to HDS [33]. It is consistent with our current study, which found that respondents needed more knowledge about assessing and managing the adverse effects due to HDS. Since the consumer-reported adverse events in our study were not confirmed by healthcare professionals, these events might be related to HDS or other causes, such as underlying conditions, other concomitant medicines. However, Consumer self-reported adverse effects remain useful as a screening tool to detect and identify potential adverse reactions from HDS.
Adverse effects related to HDS are often under-reported because these products are commonly used without the supervision of healthcare professionals. Consumers frequently seek these products as self-medication. Some consumers are not considered HDS to be medicines. Additionally, consumers rarely seek medical advice before using such products and may not disclose their use, resulting in under-reporting of adverse events relating to HDS [34, 35].
In Thailand, spontaneous reporting system was used as main method for suspected adverse reactions from conventional medicines and health products including HDS [36]. Thai consumers can report adverse events related to HDS to the HPVC themselves. However, consumer reports regarding adverse effects were relatively low. Lack of understanding of the reporting processes might discourage consumers from reporting their adverse symptoms to regulatory authorities. The FDA should increase public awareness of the importance of reporting adverse effects from HDS and offer various channels for reporting.
Despite the knowledge expressed by participants in our study regarding the indications and usage of HDS, there was a clear need for improved safety knowledge related to these products. Several studies have highlighted insufficient awareness or recognition of adverse effects, synergistic effects, and interactions between HDS and other medications [37, 38]. Additionally, online information about HDS often lacks details on potential adverse effects, drug interactions, and overall safety, particularly on retail websites [39]. Safety information of HDS should be informed to consumers to help them outweigh risk and benefits before taking these products. Pharmacists can play a pivotal role as healthcare professionals by promoting the rational use of HDS, offering unbiased information, and ensuring patients are well-informed to minimize adverse events and optimize therapeutic outcomes [40]. In this study, the majority of participants reported using HDS products that were certified by the Thai FDA. This finding reflected a potential risk mitigation behavior of consumers and suggests a relatively high level of public trust in regulatory oversight of the FDA since the FDA has raised public awareness on the use of certified HDS products.
Limitations of the study
Our study included participants from only one district in Khon Kaen province using purposive sampling, therefore, the findings might not be representative of other regions. Most participants in our study were of working age and resided in urban areas, as the data collection was conducted in a city. Therefore, the findings might reflect a population with relatively higher educational backgrounds and urban lifestyles, rather than those from rural communities. The questionnaire used in our study was validated for content validity as most items focused on individual experiences with use, adverse symptoms, and self-assessed knowledge. Although pilot test was conducted in a small sample group, reliability test was not performed. The adverse events reported by the general public were not reviewed or further assessed by other methods including healthcare professionals or using causality assessment tools. In addition, knowledge of HDS, measured by VAS, was self-perceived knowledge. There is a possibility of recall bias, especially among respondents whose experience of adverse events occurred more than 1 year ago.
Conclusions
Around half of the general public in Thailand used HDS while a small number reported adverse events from HDS. Gastrointestinal effects were the most reported adverse events, with most being mild severity. The general public had a moderate level of knowledge on the use and adverse effects of HDS. Safety knowledge regarding drug interaction between prescription medications and HDS, adverse effects of HDS and management of the adverse effects are further needed to increase the safety use of HDS.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Acknowledgements
This research project was partially supported by the Office of the Ministry of Higher Education, Science, Research, and Innovation under the Reinventing University 2024 Visiting Professor Program, Khon Kaen University. The authors would like to express our thanks to all participants who completed the questionnaires.
Abbreviations
- HDS
Herbs and dietary supplement
- DSHEA
Dietary Supplements Health and Education Act
- WHO
World Health Organization
- VAS
Visual analog scale
- IOC
Index of item objective congruence
- S.D.
Standard deviation
- aOR
Adjusted odds ratio
- FDA
Food and Drug Administration
Author contributions
KW was responsible for data collection, analysis, interpretation, manuscript drafting and revision. SS, WY, and KS were responsible for data collection, analysis, and interpretation. SP was responsible for manuscript drafting. ARC was responsible for manuscript revision. NJ was responsible for conception, supervision, design, data acquisition, and manuscript revision.
Funding
This study was supported by the Faculty of Pharmaceutical Sciences, Khon Kaen University.
Data availability
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This study was ethics approved by Khon Kaen University Human Research Ethics Committee (Number HE602353). All participants agreed to participate in the study and provided verbal informed consent. All procedures were conducted in accordance with the ethical standards of the Declaration of Helsinki.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.