Growing demand for estrogen patches to relieve menopause symptoms has led to shortages, leaving women searching multiple pharmacies or switching medications.

Experts say the shortages could last as long as three years.

More than 1 million women in the U.S. enter menopause every year, and many seek help for symptoms like hot flashes, mood changes and sleep problems.

What's more, interest in hormone replacement therapy (HRT) has grown in recent years, especially since the U.S. Food and Drug Administration (FDA) updated its messaging last year.

In November, FDA removed a long-standing black-box safety warning on these therapies, Reuters reported. 

By the end of February, use of estrogen patches jumped 26%, according to data from Truveta, a health analytics company.

Since 2023, estrogen patch use has increased 184%, while use of vaginal creams rose 122%.

But supply is falling short of the rising demand.

"When the FDA removed the safety warning in November, it created unprecedented demand that cannot fully be met at present," a spokesperson for Sandoz, a generics drug manufacturer in Switzerland, told Reuters.

A spokesperson for CVS Health told Reuters that manufacturers have not been able to supply enough product in recent weeks.

Some patients say they are worried about running out of their medication.

"I do get nervous if I were unable to get my prescription refilled, that side effects or that the symptoms of perimenopause would come back," said Amy Satterlund, a 50-year-old patient who has used the patch for about 18 months and is now struggling to find it.

Doctors warned that stopping treatment abruptly can cause symptoms to return, while switching products may lead to new side effects entirely.

Experts pointed to a number of production challenges.

Estrogen patches are generic drugs, which means they have lower profit margins. For drug makers, that means there’s less incentive to make the investments needed to produce them, Reuters explained.

"For 20 years, less than 5% of women took hormone therapy. Now those numbers are growing … and scaling up production of medications is not as easy as it might seem," Dr. Gillian Goddard, adjunct assistant professor at the NYU Grossman School of Medicine, told Reuters.

What's more, building new facilities can take years.

So, experts say, women should be prepared for shortages to persist.

"People have waited a long time to make a decision ... about whether they want to use hormones," Dr. Mary Rosser, an ob-gyn and director of Integrated Women's Health at Columbia University, said. "Then they make the decision and then they can't get them."