Does the COVID-19 vaccine affect your period?

There are well-documented common side effects of the COVID-19 vaccines — arm soreness, headache, fever and fatigue. What’s more, some women have also reported experiencing changes in their menstrual cycle after COVID-19 vaccination.

“In our clinical practice, we have seen patients with complaints of irregular and heavier menses after receiving the COVID-19 vaccine,” says Dr. Ray Kamali, a board-certified OBGYN affiliated with Sharp Chula Vista Medical Center. “This was echoed by anecdotal reports from individuals on social media and various blogs.”

However, a recent study funded by the National Institutes of Health (NIH) indicates that the changes, if connected, are minimal.

Changes remain within normal range
According to researchers, those who received a dose of a COVID-19 vaccine did have an increase in cycle length — of just one day — when compared to unvaccinated women. The experts noted that menstrual cycles regularly vary month to month, and the slight deviation of one day was within a normal range of change.

“It is important to clarify that while the study findings did show an increase in cycle length — which refers to the time between one menstrual cycle to the next — the authors did not find any changes in menstrual duration, which is the number of days of bleeding,” Dr. Kamali says.

The study authors noted that additional research is needed to determine how COVID-19 vaccination might influence other menstrual characteristics, including symptoms such as water retention, mood changes and cramps, as well as the heaviness of blood flow during menstruation.

Causes other than vaccination
According to Dr. Kamali, however, some of the menstrual abnormalities reported in the last two years likely have more to do with the lifestyle changes brought about by the pandemic and less to do with the COVID-19 vaccines.

“Some of these changes can been attributed to the social, psychological and financial stress associated with the pandemic,” he says. “This includes changes in lifestyle from a more active to a more sedentary routine and subsequent weight gain.”

Additionally, Dr. Kamali points out that the reproductive system is closely linked to other internal systems, including the immune system. It is possible that the immune response created by the vaccine can cause a short-lived change to one’s periods. “We are not exactly sure why these changes occur,” he says.

No effect on fertility
And just as the vaccines have been shown to minimally affect menstrual cycles, there is currently no evidence that COVID-19 vaccination causes infertility. This is supported by another recent NIH study that did not find any difference in pregnancy success rates from women who had natural antibodies from COVID-19 infection, antibodies from vaccination, or no antibodies at all.

“In our region in Southern San Diego, vaccination rates are over 70% in reproductive-age women,” says Dr. Kamali. “And we certainly have not seen a decrease in new pregnancies.”

While Dr. Kamali stresses he understands that the decision to receive the vaccine can be a complex one for some patients, especially those who are pregnant or are planning to conceive, he encourages them to list their concerns and have an honest conversation with their doctor.

“This conversation must include the risks associated with COVID-19 infection,” he says. “Based on the available data, due to the risks of COVID-19 infection during pregnancy to mother and fetus, vaccination is recommended to those who are pregnant, breastfeeding and planning on becoming pregnant.”

Get the latest COVID-19 information on vaccines, testing, getting care and more.