Women across the internet have been talking about this side effect.

Keeping up with the surge of "cure-all" wellness fads is a job in and of itself. In our column Wellness Inspector, we do the work for you, closely examining these trends to see if they're worth your hard-earned pennies—or whether they're just hype.
 

Ever since the COVID-19 vaccines came out at the end of December 2020, questions have been surrounding their efficacy and side effects. While intrigue first surrounded how quickly the vaccines were manufactured and who would benefit the most from their injections, a new question has arisen as the vaccines have become more widely distributed: Does the COVID-19 vaccine affect your menstrual cycle?

If you go solely off the list of side effects that your injector shares, you might not think so. After all, experts typically only mention the potential for a sore arm, headache, fever, and, in some cases, what feels like flu-like symptoms. However, if you rely on social media—as we so often do in the 21st century—you may have heard otherwise. That's because, over the past couple of months, women have taken to Twitter, Instagram, and TikTok to share that, post-vaccine injection, their periods grew heavier and more painful.

Naturally, we were intrigued when we realized this, so we reached out to a couple of doctors for their expert opinions on the matter. Keep reading to learn whether or not menstrual changes should be expected after getting your COVID-19 vaccine.

Does the COVID-19 vaccine affect your menstrual cycle?

As it currently stands, Union Square Play's Parenting expert, Maddy Travers, who has a Master's in Public Health with a focus on maternal and child health, says that we can't scientifically say that vaccines affect menstrual cycles. After all, the vaccine trials didn't assess changes to menstrual cycles, so it hasn't been studied heavily enough—yet.

With this in mind—and knowing that people had been sharing changes to their menstrual cycles on social media—Dr. Kate Clancy, an associate professor at the University of Illinois at Urbana-Champaign, launched an open survey. The goal? To uncover just how many people have experienced noticeable differences in their cycle. So far, Travers says that the survey has amassed over 22,000 responses, all of which will eventually help us to better understand the effects of the COVID-19 vaccines on menstruation.

While the responses haven't been analyzed just yet, Travers says that it is biologically plausible that a vaccine could disrupt the menstrual cycle. "We know that the vaccines are designed to produce an immune response, and an inflammatory reaction, including flu-like symptoms," she explains. "So it's possible that this inflammatory response could affect estrogen regulation and result in heavy periods. We also know that certain immune cells are involved in the shedding of the uterine lining during the menstrual cycle and could potentially be affected by a vaccine-induced immune response."

What menstrual changes can occur post-vaccine?

While it's still unclear how exactly the COVID-19 vaccines may affect menstruation, OB-GYN and Mommy Matters founder Dr. Taraneh Shirazian says that many women have reported spotting and heavier periods as a whole. With that in mind, it's important to know that, while changes may occur to your period, it's not necessarily something to be highly concerned about—unless you are experiencing extremely heavy bleeding.
 

How long do the effects last?

Since menstrual changes as a result of the COVID-19 vaccines haven't been heavily studied, it's tough to say precisely how long the effects could last. That said, Dr. Shirazian says that menstrual cycle irregularities should regulate by cycle number two. "It is very common with any new medication or new stressor on a woman's reproductive system for there to be menstrual change," she explains. "If it just happens for one cycle it is generally not something to be concerned about."
 

Remember: More studies need to be conducted.

As powerful as word of mouth is, it's important to remember that we're still waiting for more concrete information surrounding the effects of COVID-19 vaccines. Just because we have to wait for more answers to arise, however, doesn't mean that you should steer clear of getting the vaccine out of fear for how it will affect your period.

"There is no indication that women should not get the vaccine based on these anecdotal findings," Travers assures. And, on that note, a final word on the findings—or, rather, lack thereof.

"In addition to not assessing menstrual cycles, the COVID-19 vaccine trials notably did not include pregnant women," Travers shares. "There is a long history of women's health issues being neglected in public health research, which is reflected here. In fact, it wasn't until the 1990s that women were even allowed to be included in clinical trials."

Here's hoping that as we progress out of this pandemic, we can progress toward more inclusive women's health research.