Temporary change in menstrual cycles after COVID vaccine is common, study shows

BOSTON -- A new study confirms that some women will experience a temporary change in their menstrual cycles after receiving the COVID vaccine. Women had been reporting this side effect for some time.

Researchers at Washington University and the University of Illinois surveyed more than 39,000 currently and formally menstruating individuals between the ages of 18 and 80 who had been fully vaccinated against COVID-19. They found that 42 percent of people with regular menstrual cycles reported bleeding more heavily than usual after vaccination.

In addition, a significant percentage of people who did not typically menstruate, because they were on long-acting contraceptives, gender-affirming hormones, or are postmenopausal reported breakthrough bleeding. 

However, experts say the changes in menstrual bleeding are temporary and not dangerous.

In:
• Coronavirus

Mallika Marshall, MD

Mallika Marshall, MD is an Emmy-award-winning journalist and physician who has served as the HealthWatch Reporter for CBS Boston/WBZ-TV for over 20 years. A practicing physician Board Certified in both Internal Medicine and Pediatrics, Dr. Marshall serves on staff at Harvard Medical School and practices at Massachusetts General Hospital at the MGH Chelsea Urgent Care and the MGH Revere Health Center, where she is currently working on the frontlines caring for patients with COVID-19. She is also a host and contributing editor for Harvard Health Publications (HHP), the publishing division of Harvard Medical School.

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