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Evaluation of the efficacy of topical caffeine in the treatment of psoriasis vulgaris

Background: Psoriasis is a common disease which often requires long‐term maintenance therapy. In psoriatic epidermis, the level of cyclic adenosine monophosphate (cAMP) decreases. It has been reported that beta‐blockers exacerbate existing psoriatic plaque and decrease the concentration of intracellular cAMP. Caffeine is a methylxanthine that inhibits phosphodiesterase enzyme and results in a higher concentration of intracellular cAMP. Objective: Evaluation of the efficacy of topical caffeine 10% in the treatment of psoriasis. Patients and methods: The patients were treated by topical application of 10% caffeine or placebo three times per day on the right or left side of the body (randomly selected by flipping a coin). Thirty‐nine patients with stable plaque psoriasis were included in a randomized, double‐blind, placebo‐controlled, right/left comparison. The patients visited every other week for a period of 8 weeks. Their Psoriatic Area and Severity Index (PASI) scores were assessed at each visit. Results: The reductions in PASI scores measured at the four visits for the caffeine‐treated group were 2.64±2.89, 4.47±3.62, 5.73±4.16, 6.58±4.40 and for the placebo‐treated group the values were 1.45±2.32, 3.04±2.68, 4.02±3.36, 4.43±3.45, respectively. Comparing the corresponding results of the two groups, p values at the second, fourth, sixth and eighth week were 0.081, 0.083, 0.079 and 0.047, respectively. Based on presented p values, the treatment with caffeine is more effective than with placebo after 8 weeks (p<0.05), and the only side effect of caffeine is mild itching. Conclusion: Based on the results of the trial, topical caffeine is an effective, safe and inexpensive treatment for psoriasis, with a delay in action.