Higher concentrations of dithranol appear to induce hair growth even in severe alopecia areata.

Alopecia areata (AA) is the commonest autoimmune cause of non-scarring alopecia. Topical treatments including corticosteroids and irritants maybe beneficial. Studies report variable hair regrowth with dithranol (anthralin) but all used low concentrations (0.1-1.25%) and inconsistent measurements of AA severity. We report retrospective data (2005-2014) of 102 patients who had failed ultra-potent topical steroids and were referred to a specialist hair clinic for treatment with dithranol up to 3%. The severity of alopecia areata tool was used and participants graded as mild (<25%), moderate (>25 to 75%), and severe (>75%) hair loss. Compared with baseline any and at-least 50% hair regrowth [72%, 68%, 50% and 61.5%, 48.4%, 37.5%, in mild, moderate and severe AA respectively] occurred in all groups (median treatment duration 12 months). Twenty-nine patients (28.4%) were discharged with complete regrowth; with no difference in proportions in severity groups (33.3%, 29%, and 21.9%) but in the period to discharge [7.9, 6.3, and 29.4 months (p-values <.05)] for mild, moderate, and severe AA. Treatment trials of 12 months with dithranol at higher concentrations may be an option in patients who failed potent topical or intra-lesional steroids) regardless of AA severity. Randomized trials (of less staining formulations) of dithranol are warranted.