Retrospective analysis of skin photosensitivity induced by pirfenidone

Knowledge regarding the association between photosensitivity and pirfenidone is based mainly on case reports. The purpose of this article was to evaluate the clinical characteristics of photosensitivity associated with pirfenidone.

We collected studies on photosensitivity induced by pirfenidone published from 2008 to 31 August 2021 in Chinese and English for a retrospective analysis.

The median age was 70 years (range 57-80) in 22 patients with pirfenidone-induced photosensitivity. The dose at the onset of symptoms ranged from 600 to 2403 mg for the treatment of idiopathic pulmonary fibrosis. Pirfenidone-induced photosensitivity occurred within 1 week in some patients and up to 8 months in others. The most common clinical manifestation of photosensitivity caused by pirfenidone was itching on body parts exposed to sunlight (back of hands, face, neck, and limbs) in 15 patients followed by erythema in 13 patients. Histopathological examination revealed necrotic keratinocytes, lymphocytic inflammatory cell infiltrate, hyperkeratosis and liquefaction degeneration in 5 patients. The photosensitivity test showed a markedly decreased minimum erythema dose (MED) of 7-228 mJ/cm² UV-B in 4 patients and 4.86-12 J/cm² UV-A in 5 patients. The clinical symptoms were significantly improved or completely relieved with a median time of 4 weeks (range 1-8) after drug withdrawal, dose reduction or systemic and topical glucocorticoid therapy.

Clinicians should be aware of the potential phototoxic effects of pirfenidone and should inform patients to take pirfenidone during (or after) a meal, avoid sun exposure, wear protective clothing, and apply broad-spectrum sunscreen with high ultraviolet UVA and UVB protection.