Can sunscreens cause frontal fibrosing alopecia? The jury’s out

NEW YORK – Is there an association between sunscreen use and frontal fibrosing alopecia? Perhaps, but causation is far from well established, according to Henry Lim, MD.

“Frontal fibrosing alopecia is becoming more common – definitely,” said Dr. Lim, speaking in an exclusive interview at the American Academy of Dermatology summer meeting. “Those of us who see patients would see, on average, probably a few patients a week with new-onset frontal fibrosing alopecia.”

Dr. Lim, program director of dermatology research and the photomedicine fellowship at Henry Ford Hospital, Detroit, said in a presentation at the meeting that, in the medical literature, just four surveys have been identified that examined the potential association of UV filters in sunscreen preparations with the risk for frontal fibrosing alopecia (FFA).

The first survey-based study questioned 205 women – 105 of whom had FFA – about sunscreen use, finding increased risk for FFA when sunscreen use was reported at least twice a week (Br J Dermatol. 2016 Oct;175:762-7). The second study, by contrast, looked at men only, examining 17 patients with FFA and 73 control participants. This study found increased frequency of FFA in patients who reported use of sunscreen or sunscreen-containing moisturizers (Br J Dermatol. 2011 Jul;177:260-1).

The final two survey-based studies each also found increased FFA frequency in patients using sunscreens, said Dr. Lim. The first of these was the largest among the FFA studies, surveying 308 patients, 19 of whom were men, with FFA and 347 control participants (Clin Exp Dermatol. 2019 Jun;44:404-10). The other study, involving women only, compared 130 patients with FFA and 130 control participants (Br J Dermatol. 2019 Apr;180:943-4).

Several factors need to be taken into consideration when evaluating the available data, said Dr. Lim. “With any type of retrospective study, there are some limitations, recall bias being one. No. 2, the studies were not designed to look at which sunscreens’ ingredient is causing the frontal fibrosing alopecia, so all we can say is that there is an association of sunscreen with frontal fibrosing alopecia without knowing which active ingredient is involved.”

Also, “there is no conclusion that we can draw in terms of causation,” he said. Data are insufficient for this kind of inference.

Titanium dioxide, a mineral filter used in some sunscreen preparations, has also been implicated in FFA. Elemental titanium has been detected in the hair shafts of some patients with alopecia, said Dr. Lim, noting a case report and another small study. In the smaller study, 20 patients were included. Of them, 16 were FFA-affected women, 4 were unaffected women, and 1 was an unaffected man. Here, however, titanium was found in the hair shaft of all participants save the one unaffected man (Br J Dermatol. 2019 Jul;181:216-7).

However, he warned, “the studies are still early. The numbers are still relatively small that have been examined.” Furthermore, the controls, meaning individuals who did not have FFA in the study, also had titanium element in their hair shaft. All of this means that it’s too early to draw firm conclusions about whether there’s a causal relationship between titanium-containing preparations and FFA.

In questioning after the session, an audience member pointed out that sunscreens are not the sole source of titanium among topical preparations; many cosmetics and hair products also use titanium.

Dr. Lim reported financial relationships with Eli Lilly, Estee Lauder, Ferndale Laboratories, Incyte Corporation, ISDIN, Pierre Fabre Dermatologie, and Unigen.

koakes@mdedge.com