Frontal fibrosing alopecia and personal care product use: a systematic review and meta-analysis

Background: Frontal fibrosing alopecia (FFA) is a cicatricial alopecia affecting the frontotemporal hairline. Given that this scarring, immune-mediated follicular destruction most commonly affects postmenopausal Caucasian women, researchers have postulated that there are hormonal and genetic components; however, the etiology of FFA is still unknown. Recently, dermatologists have reported cases of FFA as being potentially caused by cosmetic products, such as sunscreen and shampoo. Therefore, this systematic review and meta-analysis intend to be the first to analyze the relationship between FFA and cosmetic/personal care products and treatments, including sunscreen, moisturizer, foundation, shampoo, conditioner, hair mousse, hair gel, hair dye, hair straightening/rebonding, chemical/laser facial resurfacing, aftershave, and facial cleanser. Methods: The Cochrane, PubMed, EMBASE, and Medline (Ovid) databases were searched for the relevant studies from the date of inception to August 2022. Case–control, cross-sectional, and cohort studies examining the effects of cosmetic/personal care product use on FFA, available in English full-text, were included. Analyses were performed using Review Manager, version 5.4. Results were reported as an odds ratio (OR) with a 95% confidence interval (CI); p values < 0.05 were considered significant. Results: Nine studies were included in our quantitative analyses, totaling 1,248 FFA patients and 1,459 controls. There were significant positive associations found for FFA and sunscreen (OR 3.02, 95% CI 1.67–5.47; p = 0.0003) and facial moisturizer (OR 2.20, 95% CI 1.51–3.20; p < 0.0001) use. Gender sub-analyses demonstrated a positive association for FFA and facial moisturizer in men (OR 5.07, 95% CI 1.40–18.32; p = 0.01), but not in women (OR 1.58, 95% CI 0.83–2.98; p = 0.16). Both gender sub-analyses were significantly positive for the association with facial sunscreen (Male OR 4.61, 95% CI 1.54–13.78, p = 0.006; Female OR 2.74, 95% CI 1.32–5.70, p = 0.007). There was no association found for a facial cleanser (OR 1.14, 95% CI 0.33–1.52; p = 0.51), foundation (OR 1.13, 95% CI 0.83–1.55; p = 0.21), shampoo (OR 0.49, 95% CI 0.22–1.10; p = 0.08), hair conditioner (OR 0.81, 95% CI 0.52–1.26; p = 0.35), hair mousse (OR 1.37, 95% CI 0.75–2.51; p = 0.31), and hair gel (OR 0.90, 95% CI 0.48–1.69; p = 0.74), hair dye (OR 1.07, 95% CI 0.69–1.64; p = 0.77), hair straightening/rebonding (OR 0.88, 95% CI 0.08–9.32; p = 0.92), hair perming (OR 1.41, 95% CI 0.89–2.23; p = 0.14), facial toner (OR 0.51, 95% CI 0.12–2.21; p = 0.37), or aftershave (OR 1.64, 95% CI 0.28–9.49; p = 0.58). Conclusions: This meta-analysis strongly suggests that leave-on facial products, facial sunscreen and moisturizer, are associated with FFA. While the association with facial moisturizer did not persist when stratifying for female populations, gender sub-analyses remained significant for a facial sunscreen. There was no significant relationship found with hair products or treatments. These findings suggest a potential environmental etiology in the development of FFA, particularly UV-protecting chemicals.