Contact allergy to sunscreen ingredients is unlikely to explain the increasing incidence of frontal fibrosing alopecia (FFA), allergists say.
Dr Claire Felmingham and colleagues at the Skin and Cancer Foundation, Victoria say there is a danger that unfounded concerns about triggering FFA may lead to people avoiding sunscreens and putting themselves at risk of UV damage to skin.
Writing in the British Journal of Dermatology they say there is no evidence or clinical practice experience to support the popular hypothesis that sunscreen is an environmental trigger for FFA.
Although there is an epidemiological association between increased sunscreen use and FFA this is not necessarily causal, they suggest.
And a biological mechanism for sunscreens to be a contact allergic trigger for FFA seems implausible, they add, noting that FFA also affects the occipital scalp, where sunscreen is not usually applied.
Patch testing studies linking sunscreen and FFA have been of poor design and given questionable, inconsistent results given the high sensitisation rates with many other allergens, they suggest.
They say that chemical sunscreen allergy is very uncommon and allergic contact dermatitis from titanium dioxide in sunscreens has not been reported.
In their own clinical practice spanning decades they have diagnosed a large number of patients with contact allergy to fragrances, hair dyes and preservatives but less commonly to sunscreens, and FFA has never been recorded as a coexisting diagnosis in those patients.
“In summary, we think that there is no conclusive evidence that sunscreens cause FFA by a contact allergic mechanism. We are concerned that implicating sunscreen as a cause of FFA could lead to sunscreen avoidance, especially in white populations with photodamaged skin.”