It\u2019s often only after a drug is released do we learn women might be affected totally differently from men \u2014 as with the case for two recent major studies.<\/p>\n
Specifically, the new research points to the role of estrogen, which naturally ebbs and flows over the course of a menstrual cycle.<\/p>\n
Changing levels of estrogen has major impacts across the entire body under normal circumstances. Introduce medication into the mix, and it becomes a whole different ballgame.<\/p>\n
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Women are just starting to get answers about how drugs affect them differently from men. LIGHTFIELD STUDIOS \u2013 stock.adobe.com<\/p>\n
\u201cFor too long, the menstrual cycle has been treated as background noise in health research,\u201d said Poppy Cooper, an author of one of the recent studies. \u201cThis work is part of a growing shift in that thinking and a recognition that the menstrual cycle has impacts beyond reproductive health.\u201d<\/p>\n
Here\u2019s which medications researchers are learning could be impacted by menstrual changes.<\/p>\n
COVID-19 vaccine<\/p>\n
After the COVID-19 vaccine was rolled out in 2021, people quickly caught on that the shot affected women differently.<\/p>\n
Researchers found that there were \u201csmall and temporary<\/a>\u201d changes to menstrual cycles after women were vaccinated \u2014 on average, the entire cycle (about 28 days) increased by about half a day.<\/p>\n It took another five years to find that where women were in that cycle when they got the vaccine affected how effective the vaccine was.<\/p>\n Researchers in a June study<\/a> found that women who were vaccinated at the follicular phase, about a 10-20 day stretch that starts on the first day of bleeding, were 35% more likely to get side effects than those who got the shot in the luteal phase, the span just before the period comes back.<\/p>\n People vaccinated during the follicular phase avoided infection for 200 days longer than those who got the vaccine during the luteal phase.<\/p>\n \u201cThis study treats the menstrual cycle as a variable that matters rather than a confounding variable to simply control away,\u201d Julia Craggs, a women\u2019s health doctor, told New Scientist<\/a>. \u201cWe may be sitting on a significant source of unexplained variation in how women respond to treatment and we have simply never looked in that direction.\u201d<\/p>\n A once-failed drug that hoped to cure Alzheimer\u2019s<\/p>\n A decade ago, a drug called davenutide was being tested to treat a rare brain disorder called progressive supranuclear palsy (PSP). It failed in 2012, when researchers found it wasn\u2019t effective at treating the disorder.<\/p>\n The drug was supposed to help with accumulated tau proteins, which also drives Alzheimer\u2019s, frontotemporal dementia, and schizophrenia.<\/p>\n In 2023, the data was re-examined. Researchers found that women responded to the drug while men did not \u2014 something that was hidden when they were grouped together.<\/p>\n In research released this summer<\/a>, the drug, a nasal spray, was tested on mice \u2014 they found that when female mice had the highest estrogen levels, they took up more of the drug than the males did.<\/p>\n In a small human trial (two men and six women), the results matched: women took up the drug more than men did.<\/p>\n Estrogen plays a role in blood flow around the brain and what gets through the blood-brain barrier<\/a>, which could help explain why women respond better to this drug.<\/p>\n The drug is now back in development<\/a> in Tel Aviv.<\/p>\n Dozens of other drugs<\/p>\n![\"A](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/08\/sick-woman-taking-pills-bottle-138198297.jpg\")
A 2025 paper showed that women\u2019s varying estrogen levels could affect how many common drugs are processed by the body. Rawpixel.com \u2013 stock.adobe.com<\/p>\n