April 11, 2021

Does the COVID-19 Vaccine Affect Women’s Periods?

Reviewed by: Aaron Stewart, MD

The COVID-19 vaccine has many normal side effects, including chills, fever, and muscle pain. So, naturally, it’s normal to wonder if the vaccine can influence other aspects of your health, like your menstrual cycle. 

According to the Centers for Disease Control and Prevention (CDC) and American College of Obstetricians and Gynecologists (ACOG), there’s no reason to put off getting vaccinated if you’re on your period. 

Learn more about the effects of the COVID-19 vaccine on your period.

Temporary Effects of Vaccine on Women’s Period

Many women have taken to social media to talk about how they’re experiencing heavier-than-normal or painful periods and other menstrual changes after getting vaccinated.  

Aaron Stewart, MD of Baptist Health Medical Group Obstetrics and Gynecology adds, “While some women have reported changes in their menstrual cycle with both the COVID-19 infection and the vaccine, the changes are generally thought to be temporary.”

What is Causing Women to Experience Heavy Periods?

For now, experts don’t know for sure. Some doctors believe that post-vaccine aches and pains may compound normal menstrual pains. The heavier flow some women are experiencing is harder to explain.

A small study of 233 women of childbearing age with clinically diagnosed COVID-19 reported some menstrual changes. Of the 177 women with records about their periods, 25% had menstrual volume changes, 20% had a lighter-than-usual period, and 19% had a longer-than-usual cycle, according to the study, which was published in Reproductive BioMedicine Online. It’s not known whether the COVID-19 vaccine could have a similar effect.

Other doctors think that stress may play a role. While stress is a vague reason for period-related changes, it could be a possibility. Women, like everyone, are feeling the stress that comes with living through a pandemic. Menstrual cycles can be affected by many factors, including stress, poor sleep, exercise, and some medications. That said, it wouldn’t be unusual for some women to notice changes in their menstrual cycle after getting vaccinated.

Is There Research on COVID-19 Vaccines Impact on Menstrual Cycles?

To date, not really. The CDC has a Vaccine Adverse Event Reporting System, which is a surveillance program that allows anyone to report the side effects they experienced after getting the vaccine.

The lining of the womb is part of the immune system. One theory suggests that after vaccination, immune cells can be affected, causing the womb lining to shed and lead to spotting or early periods.

“The exact mechanism for this alteration is not clear, but similar changes can be noted in women during times of stress or when their bodies are dealing with other significant infections and/or inflammatory responses,” Dr. Stewart said. 

Find a Women’s Care Provider Near You

A woman’s body is capable of phenomenal things. But being a woman also comes with unique health challenges. At Baptist Health, we’re dedicated to providing women the services they need to protect their health, at every age and stage. From attentive mother and baby care to comprehensive breast health and gynecologic services, we partner with women to help you attain your very best health, throughout your life. Find a provider near you today.

What If My Period Changes After I Get Vaccinated?

Most importantly, don’t panic. While it could be related to the vaccine, it also may be a sign of something else that coincidentally showed up after you were vaccinated. 

“I would advise my patients to do a home pregnancy test if there is concern for this as I would any patient with a similar menstrual alteration, or simply for peace of mind,” Dr. Stewart said.

If the change persists, call your doctor. Even though it could be related to the COVID-19 vaccine, it’s best to discuss it with your healthcare provider because they may recommend certain evaluations, such as a gynecologic exam or pelvic ultrasound.

How Long Do Menstrual Cycle Changes Last?

Vaccine studies have shown these changes generally only appear in the first few days after vaccination. Additionally, most women who report changes to their menstrual cycle, have only report those changes in the first cycle after vaccination with a return to baseline thereafter.

The Benefits of the Vaccine Outweighs Temporary Period Changes

“The possibility of any menstrual pattern disruption should not deter women from receiving this important vaccine,” said Dr. Stewart. “There is not yet a large body of data on this issue, but with more young women receiving the vaccine, this will change. Patients would be encouraged to submit their experience via the CDC V-safe app in an effort toward improving our overall knowledge in this area.”

While not much is known about the effect of the COVID-19 vaccine on women’s menstrual cycles, experts agree that it shouldn’t stop you from getting vaccinated.

If you have more questions about the Pfizer or Moderna vaccines, please visit the CDC.

To schedule your first, third or booster dose, visit ScheduleYourVaccine.com to find available appointments.

Next Steps and Useful Resources: 

What You Need to Know About Your Vaccine Card
Importance of Cancer Screening During the COVID-19 Pandemic
Vaccine Myths vs. Reality
What to Expect After the COVID-19 Vaccine
Importance of Cancer Screening During the COVID-19 Pandemic

Learn More.