We know some medications work differently in men and women. Why is it taking so long for studies to reflect this?The first step, they say, is admitting you have a problem, and on that front the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has made some much-needed progress. The agency, which is responsible for approving all clinical trials in the UK, has identified a “notable imbalance” in trials conducted between 2019 and 2023: there were nearly twice as many all-male trials as all-female trials.This imbalance is hardly surprising: as I documented in Invisible Women, my book on the female data gap, the failure to adequately represent women in clinical trials is a longstanding and global problem. The MHRA’s figures are also in line with a recent US analysis that found male-prevalent diseases receive nearly twice as much funding as female-prevalent diseases, both absolutely and relative to disease burden. So far, so disappointingly standard.Caroline Criado Perez is the author of Invisible Women: Exposing Data Bias in a World Designed for MenDo you have an opinion on the issues raised in this article? If you would like to submit a response of up to 300 words by email to be considered for publication in our letters section, please