Phototherapy is a proven treatment for various skin disorders, but it is also effective for preventing certain seasonal photodermatoses through the induction of phototolerance (photohardening).

Combalia et al.1 describe their experience with the use of fixed-regimen phototherapy to prevent polymorphic light eruption. The protocol consisted of 8 sessions in which the patients received fixed starting and incremental doses, regardless of skin type and the fact that over half of the patients had some degree of photosensitivity. The treatment produced satisfactory results in 87% of cases, although treatment success does not necessarily mean full or lasting tolerance for the whole summer.

Phototherapy is undoubtedly a safe treatment. While short, treatment triggers polymorphic light eruption reactions in a third of patients, but this does not limit treatment or alter prognosis, suggesting that it might be interesting to routinely administer prophylactic oral corticosteroids during the first few sessions, as some of us do with atopic dermatitis.

Phototolerance does not last indefinitely and is lost relatively quickly if the patient does not continue to receive moderate doses of sunlight throughout the summer. While this prevents the health risks associated with tanophobia, it also requires scheduling treatments to end at the beginning of the summer (May or June).

Although larger series of patients are needed to confirm the results of Combalia et al.,1 studies such as this highlight the need to improve the use of phototherapy in polymorphic light eruption, a condition that frequently affects quality of life and has few real preventive options.