Table 5.
Studies that evaluated the association of hair straighteners with alopecia.
| Author | Study type | Population | Hair straightener | Scalp alterations |
|---|---|---|---|---|
| Khumalo et al.,22 2007. | Case series | n = 5 (F:5, M:0) | Sodium hydroxide (n = 3) and Guanidine hydroxide (n = 2) | Irritative symptoms and development of areas of cicatricial alopecia. Histological findings of perifollicular lymphocytic infiltrate, follicular fibrosis, and premature desquamation of the inner root sheath. |
| Shah & Alexis,23 2010. | Case series | n = 69 (F:67, M:2) (64: data on hair care) | Chemical relaxers | Straighteners were the most common traumatic practice in patients with CCCA. It was not possible to establish an association due to the absence of a control group. |
| Gathers et al.,24 2009. | Case-control study | n = 101 (F:101, M:0) | Chemical relaxers | There is no relationship between the use of relaxers, their frequency of application or complications from their use with the development of CCCA. |
| CCCA Group (n = 51). | ||||
| Group without cicatricial alopecia (n = 50). | ||||
| Olsen et al.,25 2011 | Case-control study | n = 529 (F:529, M:0) | Chemical relaxers | No association was observed between the use of straighteners or reaction to their use with extensive central hair loss. |
| Association between age at first hair straightening and hair loss pattern when comparing pattern 0 (no loss) vs. patterns 3 and 5 (probable CCCA). | ||||
| Rucker et al.,26 2011. | Cross-sectional (questionnaire) | n = 201 (F:201, M:0) | Chemical relaxers | Hair straightening was a risk factor for traction alopecia (OR = 2.2; (95%CI 1.1–4.5; p = 0.03). Straightening associated with cornrow braids: OR = 5.27 (95% CI 1.5–18.32; p = 0.009). |
| Ogunbiyi et al.,27 2014. | Case report | n = 1 (F:1) | Chemical relaxers | Hair loss associated to generalized proximal trichorrhexis nodosa, with atopy as the baseline condition. |
| Amorim et al.,32 2017. | Cross-sectional | n = 30 (F:30, M:0) | Sodium hydroxide or guanidine hydroxide. | Areas of permanent alopecia were found where an artificial hair implant of Italian-knot type had been associated with hair straightening. |
n, Number of patients; F, Female; M, Male.