Effect of Topical Sesame Oil on the Severity of Pain in Patients With Limb Trauma: A Randomized Controlled Trial

Abstract

Objective

The purpose of this study was to investigate the effect of topical use of sesame oil on pain severity in patients with limb trauma.

Methods

A placebo-controlled randomized controlled trial was conducted on 120 patients with nonpenetrating upper and lower limb traumas admitted to the trauma emergency department. The patients were allocated to either the sesame oil group or the placebo group using the stratified random sampling technique based on trauma size and age. Depending on the trauma area, sesame or placebo oil were poured on the trauma site and massaged for 5 to 7 minutes. The intervention was repeated twice a day for 3 days at home. Pain severity was measured using the numeric pain scale before intervention on the first day and 30 minutes after each intervention for 3 days, twice a day. Data were analyzed using descriptive and analytical tests including the independent t test, χ² test, Fisher exact test, Mann-Whitney U test, Friedman test, and multiple linear regression analysis. The significance level was set at 0.05.

Results

The decreasing trend of pain was significant in both the intervention and placebo groups (P < .001). Comparison of the trend of changes in pain scores between the 2 groups showed that the mean changes of pain severity were higher in the intervention group compared with the placebo group in all assessments. There was a significant difference in the rate of analgesic consumption in the intervention group compared with the placebo group (P < .001). However, there was no significant difference between the 2 groups regarding pain severity. Pain reduction was negatively associated with body mass index (b = –0.091, P = .003), amount of received pain medication (b = –0.001, P = .039), and area of trauma (b = –0.002, P = .039). Pain reduction was greater in male patients than female patients (b = 0.676, P = .015). The effect of sesame oil on pain changes was not significant. No adverse side effects were reported.

Conclusion

This study showed that despite less use of analgesics in the intervention group than in the placebo group, sesame oil did not have any statistically significant effects on the severity of limb trauma pain. Further research is needed regarding the effect of topical sesame oil application on pain as a safe and uncomplicated intervention.

Introduction

Trauma is recognized as a serious threat to public health, imposing a great burden of disease and disability on individuals.¹ In Iran, trauma is the leading cause of mortality, morbidity, and disability. Among different types of trauma, nonpenetrating trauma (blunt injury) is more common than penetrating trauma. Also, limb trauma is the most prevalent organ injury, following head injury.^2,3 Nonpenetrating trauma, depending on its mechanism and severity, causes several complications, such as bruises, abrasion, rupture, fracture, hematoma, and pain.⁴

Pain, as a highly subjective and multi-factorial experience, is described as an unpleasant feeling associated with tissue damage.⁵ It is known that factors, such as culture, previous experience of pain, beliefs, moods, and coping abilities, affect the experience of pain.⁶ Acute pain is an important source of fear for many patients, affecting the treatment process and the patient's overall experience of pain.⁷ Overall, the experience of pain is stressful for individuals and can affect their lifestyle and feelings of satisfaction and comfort.⁶ It may also lead to discomfort, loss of control and function, fatigue, and impaired quality of life, personal relationships, and daily activities.⁸ Meanwhile, poor treatment may have adverse consequences for patients.⁶

Posttraumatic pain is a major source of concern for patients; therefore, acute pain management should be performed effectively.⁷ However, according to the literature, pain management is not appropriately performed.^9,10 It has been shown that the use of pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and narcotics, for pain management has adverse consequences for both the individual and the society, despite their desirable sedative effects. Globally, almost $7 billion is spent on the production of NSAIDs each year, imposing a heavy economic burden on societies. On the other hand, NSAIDs have many side effects, including gastrointestinal disorders (eg, gastrointestinal bleeding).¹¹ Narcotics also cause mental disorders and respiratory depression. Besides, through facilitating the release of histamine, they lead to the dilation of blood vessels, reduction of blood pressure and heart rate, and urinary retention.¹² Concerning the negative effects of these drugs, it is suggested to use alternative pain relievers.¹¹

In recent years, owing to the side effects of chemical drugs and increased microbial resistance, more attention has been paid to herbal medicines as alternatives to modern treatments for several chronic diseases.^13,14 Sesame oil, which is extracted from the seeds of the sesame plant (scientifically called Sesamum indicum L.), is among natural substances with anti-inflammatory and analgesic activities. The oil of this plant is a rich source of unsaturated fatty acids and lignans, such as sesamolin and sesamin, which are described as alternative food supplements and anticancer, analgesic, and anti-inflammatory agents.¹⁵

Analysis of the anti-inflammatory and analgesic effects of sesame oil in animal experiments has shown promising results for relieving pain and inflammation; however, further studies are needed for human application.^16,17 According to the literature, sesame is effective in alleviating pain and inflammation.18, 19, 20 However, further research is needed to consider sesame oil as a safe and inexpensive alternative in pain management guidelines.17, 18, 19, 20, 21 Therefore, the present study aimed to determine the effects of topical use of sesame oil on pain severity in patients with limb traumas, referred to a trauma center in the north of Iran.

Methods

Design Study

This placebo-controlled randomized trial was performed on outpatients with upper and lower limb traumas, referred to the trauma emergency department of the Poursina Medical Training Center in Rasht, Iran, from May to September 2019. This referral center provides services for all patients with traumas in the Guilan province. The samples and statistician were blinded.

Participants

One hundred and twenty patients were selected based on the inclusion criteria and classified into 2 groups using the stratified randomized block sampling method with respect to trauma size (<100 cm² and >100 cm²) and age (18-40 and 41-60 years). Each group (intervention and placebo) consisted of 60 participants. To maintain concealment during sampling, the blocks were kept in a sealed envelope. The inclusion criteria were nonpenetrating trauma to the right and/or left limb or upper and/or lower limb; a pain score of 3 to 6; passing less than 6 hours after trauma; full consciousness; having no fracture, bleeding, dislocation, amputation, foreign body embedment, nerve damage, or fever; and insensitivity to sesame. Fractures were assessed by emergent x-ray, and bleeding was assessed by physical examination. The exclusion criteria were reaction or allergy to the intervention (topical application of sesame oil on the trauma site) and irregular follow-up (missing more than 2 follow-ups).

Ethics

This study was approved by the ethics committee of Guilan University of Medical Sciences (IR.GUMS.REC.1397.437) and registered at the Iranian Center for Clinical Practice with the Clinical Trial Registration Number IRCT20180701040297N2.

Sample Size

The sample size was calculated, based on a similar study,¹⁸ using the following formula (α = 0.05, β = 0.1, μ₁ = 5.5, μ₂ = 4.95, δ₁ = 1.42 and δ₂ = 1.58):

$$n=\frac{{\left(Z_{1-\frac{\alpha }{2}}+Z_{1-\beta }\right)}^2\left({\delta }_1^2+{\delta }_2^2\right)}{{\left({\mu }_1-{\mu }_2\right)}^2}$$

Measurement Tools

The following tools were used to collect the data: (1) a questionnaire of demographic information (eg, age, sex, marital status, level of education, and occupation), clinical characteristics of trauma (ie, upper and/or lower right and/or left limb), trauma size, type of injury (joint and/or nonjoint), body mass index (BMI), history of smoking, history of herbal medicine use, history of analgesic use over the past 3 months, complications during the intervention (eg, allergy, bleeding, and infection), trauma-related complications (eg, ecchymosis and erosion), frequency of using hot or cold compress, and amount and type of analgesia received during the intervention; (2) numeric pain scale; and (3) a standard ruler for measuring the size of the trauma.

Interventions

After obtaining the required permissions and attending the emergency department, the researcher selected the participants among trauma patients based on the inclusion criteria. Data were obtained from medical records and interviews with patients. Written informed consent was obtained after explaining the objectives of the study and ensuring the participants about the confidentiality and anonymity of data.

For both groups, first, a member of the research team (unaware of the type of oil and the patient's group) measured the size of trauma site based on the patient's report of injury range using a flexible curved ruler (by multiplying the greatest length of the trauma site by its greatest width in centimeters). Next, the trauma site was washed with 100 cc of normal saline, and 10 drops of sesame oil or paraffin (about 3.8 cc per 250 cm of trauma area) were poured on the trauma area using a dropper, based on the trauma size. The entire surface of the trauma site was smeared with sesame oil or placebo oil and massaged in circular motions for 5 to 7 minutes.

In the intervention group, standardized topical sesame oil (health license number: 18564/21; Narmak Pharmaceutical Company, Tabriz, Iran) was used, while in the placebo group, a solution similar to sesame oil (paraffin; health license number: 17367/21; Narmak Company, Tabriz, Iran) in terms of consistency, color, and appearance was used. After implementing the intervention, the researcher educated the participants on how to apply the oil twice a day for 3 days. They were also instructed about routine care, including the application of cold compress within the first 24 hours, warm compress within the next 48 hours, and use of analgesics to relieve pain. The severity of pain was assessed 7 times (before the intervention on the first day and 30 minutes after each intervention for 3 days, twice a day), using the numeric pain scale. According to the literature, the absorption time of the sesame oil through the skin is approximately 30 minutes,²² and acute pain lasts less than 72 hours.⁶ During the study, the researcher called the participants twice a day to remind them of the intervention. The participants were inquired about the severity of pain via phone calls. The patients, data collector, and data analyst were unaware of the type of oil used for the participants.

Statistical Analysis

Data were analyzed using descriptive (mean, standard deviation, frequency, and percentage) and analytical tests (univariate and multivariate analysis) in SPSS Statistics version 21.00 (IBM, Armonk, NY). The Shapiro-Wilk test was used to assess normality of variables distribution. In order to compare between-group differences for the continuous variables, an independent t test was used, and if no normal distribution, the Mann-Whitney U test. The χ² and Fisher exact tests were used to compare between-group differences for categorical variables. Pain scores were not normally distributed, and, therefore, the Friedman test was used to compare pain scores at different times in every group.

Stepwise multiple linear regression analysis was used to identify factors associated with pain score changes. The variables with a P value <0.1 by univariate analysis were selected as the independent variables, and pain score changes was the dependent variable. The criteria for entering and removing variables was P_entry = .05 and P_removal = .1. The assumptions of the multiple linear regression were investigated and met.²³ Linearity was confirmed with scatterplots of pain with each independent variable. The Variance Inflation Factor values were less than 10, and, therefore, multicollinearity in the data was not problematic. Homoscedasticity was verified by a scatterplot of residuals versus predicted values. The residuals of the regression were normally distributed (P = .84). The value of the Durbin-Watson test was 1.685, and, therefore, autocorrelation in residuals errors was rejected. Cook's distance was used for identifying outliers and assessing their influence in the regression model. The outliers were few (<5%) and not influential (Cook's distance values <0.5), and, therefore, there was no need to delete them. The significance level was set at 0.05, and 95% confidence intervals (CIs) were reported as appropriate.

Results

In the present study, from 329 primary patients, 202 patients were excluded (Fig 1). The 2 groups were similar in terms of demographic and clinical characteristics (Table 1). As shown in Table 2, there was no significant difference between the 2 groups in terms of pain severity in any of the assessments. Also, the decreasing trend of pain was significant in both intervention and placebo groups (P < .001). Comparison of the trend of changes in pain scores between the 2 groups showed that the mean changes of pain severity were higher in the intervention group, compared with the placebo group in all assessments.

Fig. 1.

Consolidated Standards of Reporting Trials (CONSORT) flow diagram of study.

Table 1.

Comparison of Demographic and Clinical Variables in the Study Groups.

Variable		Study Groups		P Value
		Placebo (N = 60)	Intervention (N = 60)
		Mean ± SD or n (%)	Mean ± SD or n (%)
Age (y)		40.37 ± 14.63	38.89 ± 14.25	.57a
Body mass index (kg/m2)		27.00 ± 4.88	26.17 ± 4.43	.08a
Trauma size (cm2)		147.79 ± 122.78	157.99 ± 137.81	.66a
Sex	Female	31 (51.67)	25 (41.67)	.27b
	Male	29 (48.33)	35 (58.33)
Education	Illiterate	4 (6.57)	3 (5.00)	.97c
	Less than high school diploma	26 (43.33)	25 (41.67)
	High school diploma	19 (31.67)	20 (33.33)
	University degree	11 (18.33)	12 (20.00)
Marital status	Single	12 (20.00)	17 (28.33)	.28b
	Married	48 (80.00)	43 (71.67)
Job status	Housewife	16 (26.67)	15 (25.00)	.92b
	Worker	7 (11.67)	7 (11.67)
	Employee	8 (13.33)	11 (18.33)
	Self-employed	16 (26.67)	17 (28.33)
	Other	13 (21.67)	10 (16.67)
Smoking	Yes	13 (21.67)	15 (25.00)	.66b
	No	47 (78.33)	45 (75.00)
Drug abuse	Yes	2 (3.33)	4 (6.67)	.4c
	No	58 (96.67)	56 (96.33)
Complication of trauma	Erosion	1 (1.67)	0 (0.00)	.62c
	Ecchymosis	14 (23.33)	14 (23.33)
	Both	8 (13.33)	5 (8.33)
	Non	37 (61.67)	41 (68.33)
Injury type	Joint	53 (88.33)	49 (81.67)	.68b
	Nonjoint	7 (11.67)	11 (18.33)
Trauma site	Upper right	18 (30.00)	14 (23.33)	.22b
	Lower right	5 (8.33)	13 (21.67)
	Upper left	19 (31.67)	18 (30.00)
	Lower left	18 (30.00)	15 (25.00)
Cold compress number		0.05 ± 0.22	0.1 ± 0.35	.45d
Hot compress number		0.17 ± 0.69	0.27 ± 0.95	.51d

SD, standard deviation.

^aIndependent t test.

^bχ² test.

^cFisher exact test.

^dMann-Whitney U test.

Table 2.

Comparison of the Severity of Pain in Different Intervals in the Intervention and Placebo Groups.

	Study Groups
	Placebo (N = 60)		Intervention (N = 60)
Variable	Mean ± SD	Median	Mean ± SD	Median	P Value
T0	6.00 ± 0.00	6	6.00 ± 0.00	6	.4a
T1	5.23 ± 0.50	5	5.07 ± 0.60	5	.06a
T2	5.00 ± 0.69	5	4.92 ± 0.62	5	.46a
T3	4.40 ± 0.69	4	4.10 ± 0.90	4	.07a
T4	4.02 ± 0.85	4	3.7 ± 1.00	4	.16a
T5	3.03 ± 1.66	3	2.67 ± 1.63	3	.19a
T6	2.98 ± 1.63	3	2.62 ± 1.64	3	.21a
	<.001b		<.001b

T0, before intervention; T1, after first intervention; T2, after second intervention; T3, after third intervention; T4, after fourth intervention; T5, after fifth intervention; T6, after sixth intervention.

^aMann-Whitney U test.

^bFriedman test.

Thirty minutes after the first intervention, the rate of pain reduction was higher in the intervention group (–0.9 ± 0.6), compared with the placebo group (–0.7 ± 0.5), and the difference was statistically significant (P = .05). Also, 30 minutes after the third intervention (24 hours after the onset of intervention), the rate of pain reduction was higher in the intervention group (–2.00 ± 0.90), compared with the placebo group (–1.60 ± 0.69), and the difference was statistically significant (P = .04) (Table 3).

Table 3.

Comparison of Changes in the Pain Severity Score Between the Intervention and Placebo Groups at Different Intervals.

	Study Group
	Placebo (N = 60)		Intervention (N = 60)
Variable	Mean ± SD	Median	Mean ± SD	Median	P Value
T0, T1	–0.70 ± 0.50	–1	–0.90 ± 0.60	–1	.05a
T0, T2	–1.00 ± 0.69	–1	–1.08 ± 0.62	–1	.46b
T0, T3	–1.60 ± 0.69	–2	–1.90 ± 0.90	–2	.04b
T0, T4	–1.98 ± 0.85	–2	–2.30 ± 1.00	–2	.12b
T0, T5	–2.97 ± 1.66	–3	–3.33 ± 0.63	–3	.15b
T0, T6	–3.02 ± 1.63	–3	–3.38 ± 1.64	–3	.16b

SD, standard deviation; T0, before intervention; T1, after first intervention; T2, after second intervention; T3, after third intervention; T4, after fourth intervention; T5, after fifth intervention; T6, after sixth intervention.

^aIndependent t test.

^bMann-Whitney U test.

Regarding the consumption of analgesics, the mean and standard deviation of analgesic consumption were 910.39 ± 396.67 and 1595.83 ± 2098.47 mg in the intervention and placebo groups, respectively. Also, the results of Mann-Whitney U test showed a significant difference in the rate of analgesic consumption between the 2 groups (P < .001). No complications were observed in either of the groups.

Moreover, stepwise multiple linear regression model was used to determine factors related to pain score changes. Pain reduction changes were negatively associated with BMI (b = –0.091, P = .003), analgesic consumption (b = –0.001, P = .039), and area of trauma (b = –0.002, P = .039). Moreover, pain reduced more significantly in male patients than female patients (b = 0.676, P = .015). Based on the present results, the effect of sesame oil on pain changes was not significant (Table 4).

Table 4.

Stepwise Multiple Linear Regression Analysis of Factors Associated With Pain Score Changes.

Model	B	Standard Error	T	P Value	95% Confidence Interval for B
					Upper Boundary	Lower Boundary
Constant	5.227	0.981	5.328	<.001	3.284	7.170
Body mass index	–0.091	0.030	–3.016	.003	–0.151	–0.031
Amount of pain medication received	–0.001	0.001	–2.093	.039	–0.002	0.0001
Sex (male)	0.676	0.275	2.459	.015	0.131	1.221
Trauma area	–0.002	0.001	–2.089	.039	–0.004	0.0001

B, unstandardized beta coefficients; T, T-test value.

Discussion

In the present study, pain severity had a decreasing trend in both groups during the study (ie, 72 hours). Although pain severity was lower in the intervention group than the placebo group, the difference was not significant. This finding is inconsistent with the results reported by Shamloo et al,¹⁸ which showed that the severity of pain on the first day was not significantly different between the 2 groups (P = .06), whereas the difference became significant after 72 hours. Moreover, researchers performed a study to investigate the effects of gentle massage with sesame oil on reducing pain in patients with limb traumas. They reported a significant difference in pain severity between the intervention (topical sesame oil) and control (topical paraffin) groups on the first day of the intervention. After the sixth day, the amount of pain was significantly different between the 2 groups.²⁴

It seems that sesame helps relieve pain by inhibiting pain transmission pathways or improving blood flow and oxygenation to tissues.²⁵ Meanwhile, further pain relief in the intervention group could be attributed to the anti-inflammatory effects of sesame oil on prostaglandins and leukotrienes, which block cyclooxygenase pathways and reduce pain.¹⁵ The effects of topical application of sesame oil on acute pain may be influenced by confounding factors, which significantly contribute to differences between the 2 groups.

In the present study, pain changes were significantly different between the 2 groups only on the first and third days of the intervention compared with the preintervention stage. Contrary to the present study, one study²⁴ showed significant changes in pain severity between the intervention and placebo groups on the third day versus the first day (P = .049). The difference observed on the third day can be attributed to differences in the amount and type of analgesics used, the patient's perception of pain (affected by cultural background), genetic factors, and the age of the participants (15-45 years in the study by Nasiri and Farsi). In the present study, factors, such as the use of analgesics (amount and type) and cold compress, which showed reducing effects on pain severity within the first 24 hours after trauma, may be some other causes of significant change in pain during the study.

According to the present findings, a higher BMI is associated with less significant changes in pain severity. In this regard, Okifuji and Hare²⁶ showed that pain and obesity were significantly correlated; in other words, the prevalence of pain complaints was higher in people with obesity. Besides, it was found that patients with obesity used more analgesics than patients with a normal weight.²⁶ Moreover, Walsh et al²⁷ found that weight gain is directly associated with pain. Therefore, sesame oil can be used at higher frequencies in people with a higher BMI owing to the higher level of body fat.²⁸

In the present study, analgesic use was inversely correlated with pain reduction. In the study conducted by Nasiri and Farsi, no significant difference was observed between the 2 groups in terms of pain severity changes during the study (9 days) or analgesic use (the difference was not evaluated on the third day). Besides, analgesic consumption had no significant effects on pain changes. In contrast to the present study, Nasiri and Farsi only used one type of analgesic.²⁴ Therefore, the discrepancy between the findings may be attributed to different types of analgesics used.

In the present study, a smaller area of ​​trauma was associated with fewer changes in pain severity. To justify this finding, it seems that a larger area of ​​trauma is correlated with greater cell damage, and more inflammatory mediators are released from the cells. Accumulation of these substances around pain nerve fibers can cause more pain; therefore, changes in pain relief are less significant.²⁴ Moreover, in the present study, male patients experienced more pain relief than female patients. In this regard, Becker and McGregor²⁹ investigated the association between sex and pain, and reported that opioid receptors caused more unpleasant pain in female patients than in male patients when they were triggered by peripheral pain in the brain. Besides, women are more sensitive to pain and report more severe pain than men when experiencing similar diseases and injuries.²⁹ Therefore, the greater change of pain relief in male patients than in female patients may be owing to female patients’ reports of greater pain and their physiological conditions.

Finally, according to the present findings, topical application of sesame oil had no significant effects on pain relief. In the study by Nasiri and Farsi, the effect of sesame oil on pain changes was not significant on the third day of the intervention, while in the study by Shamloo et al, sesame oil exerted significant effects on pain relief on the third day (P = .001).¹⁸ Also, another study¹⁹ by these researchers on patients with cancer, experiencing chemotherapy-induced phlebitis, reported that massage with sesame oil reduced the severity of pain in patients. In line with the present study, Nasiri and Farsi used placebo for the control group, while Shamloo et al applied no intervention for the control group. The insignificant effect of sesame oil on pain changes in the present study could be related to the effect of massage in the placebo group, the participants' fear of the intervention owing to pain, inappropriate reporting of pain, and reduction of pain over time. Overall, these factors might have influenced the results and might have diminished the effect of sesame oil on pain intensity in the sesame group.

Limitations

First, this study was based on the participants’ self-reports; therefore, we could not precisely control variables related to analgesic consumption or use of hot and cold compress during the study. Second, massage for the placebo group and the use of different analgesics might have affected the results. Therefore, it is recommended to prescribe only 1 type of analgesic in future studies and to include a third control group without intervention.

Conclusion

The present study showed that despite more pain relief and less use of analgesics in the intervention group than the placebo group, sesame oil did not have any statistically significant effects on the severity of limb trauma pain. Also, the effect of sesame oil on the severity of pain was influenced by sex, BMI, area of ​​trauma, and the amount of analgesics used.

Acknowledgments

The authors acknowledge the Deputy of Research and Technology of Guilan University of Medical Sciences.

Funding Sources and Conflicts of Interest

No funding sources or conflicts of interest were reported for this work.

Contributorship Information

Concept development (provided idea for the research): M.K.M., N.J.P.

Design (planned the methods to generate the results): M.K.M., N.J.P., F.J., F.Y., E.K.N.

Supervision (provided oversight, responsible for organization and implementation, writing of the manuscript): N.J.P.

Data collection/processing (responsible for experiments, patient management, organization, or reporting data): M.K.M., N.J.P., E.K.N.

Analysis/interpretation (responsible for statistical analysis, evaluation, and presentation of the results): N.J.P., E.K.N.

Literature search (performed the literature search): M.N.M., N.J.P.

Writing (responsible for writing a substantive part of the manuscript): M.N.M., N.J.P.

Critical review (revised manuscript for intellectual content, this does not relate to spelling and grammar checking): N.J.P., F.J., F.Y., E.K.N.

Practical Applications.

• •This study investigated the effect of topical use of sesame oil on pain severity in patients with limb trauma.
• •A placebo-controlled randomized controlled trial was conducted on 120 patients with nonpenetrating upper and lower limb traumas admitted to the trauma emergency department.
• •This study showed that sesame oil did not have any statistically significant effects on the severity of limb trauma pain but reduced the amount of analgesics used.

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