Minoxidil 5% foam costs a mean of 40% more when it’s marketed to women instead of men, according to a review of 24 pharmacies in four northeastern states.

The statistically significant difference – $11.27/30 mL versus $8.05/30 mL – “could be a result of differential pricing by gender or could reflect production costs that are not related to medication strength,” reported the investigators from the University of Pennsylvania, Philadelphia. Also, the formulation for women, approved in 2014, is still on-patent and available only as Rogaine, whereas generics are available for the men’s foam (JAMA Dermatol. 2017 Jun 7. doi: 10.1001/jamadermatol.2017.1394 ).

The team also found that women’s 2% minoxidil solution costs about the same as men’s 5% minoxidil solution, despite the difference in strength ($7.61/30 mL versus $7.63/30 mL).

“These are products with the exact same ingredients. They come in different amounts and packaging based on gender, so, for the most part, women probably do not even realize they are paying more,” lead author Jules Lipoff, MD , of the department of dermatology, said in a University of Pennsylvania press release . “We recommend that our female patients buy the male version of the product because it doesn’t seem right to ask a woman to pay more when the products are, for all intents and purposes, identical,” he said.

Gender-based price differences – the “pink tax” – have been documented in consumer products before. A 2015 report found that women pay about 13% more than men for equivalent personal products in New York City. “However, to our knowledge, gender-based price differences for medications have not been previously studied,” the investigators said.

Pricing data came from CVS, Kroger, Rite Aid, Target, Walgreens, and Walmart pharmacies in Pennsylvania, New York, Ohio, and Indiana. The analysis included 14 OTC minoxidil preparations marketed to women and 27 marketed to men. Products were matched based on concentration and inactive ingredients to arrive at overall prices. When prices varied for the same product at different stores in the same chain, the mean price was used.

Dr. Lipoff reported receiving a grant from Pfizer. No other disclosures were reported.