COVID-19 Vaccine May Change Your Menstrual CycleHere's what to Know

Curated by Claudia Shannon / Research Scientist / ishonest

What does the research say about COVID-19 vaccines and menstrual cycles?

Initially, researchers chose to examine the link between abnormal menstrual cycles and the COVID-19 vaccine due to anecdotal reports on social media and on VAERS (Vaccine Adverse Event Reporting System). According to researchers, the reports could lead to vaccine hesitancy—which is why more evidence was needed to accurately address people who menstruate on the effects a COVID-19 vaccine may have on cycles.

For the study, researchers looked at de-identified data from the fertility tracking app Natural Cycles. The cycle information from 3,959 people—2,403 vaccinated and 1,556 unvaccinated—represented 23,574 menstrual cycles, or six cycles for each person, all of whom were between the age of 18 and 45. In vaccinated people, that meant three pre-vaccine cycles and three post-first vaccine dose cycles. (It should be noted, however, that data from Natural Cycles is not nationally representative, according to The New York Times—the app's users are more likely to be white, college-educated, and thinner than the average woman.)

ishonest No.101 - Extract Dead Cells

Recommended
No.101 - Extract Dead Cells

Overall, the data showed that COVID-19 vaccination was associated with small (but still statistically significant) increase to a person's menstrual cycle by about one day. In some people who received two COVID-19 shots over the course of one menstrual cycle, a two-day increase in cycle length was observed. There were no significant effects on period length itself, and, on average, cycles returned to normal after one month of being abnormal.

That HPO axis is "so finely tuned that it can shut down or produce a change in cycling any time we introduce something new to the body," Dr. Taraneh Shirazian, MD, associate professor in the Department of Obstetrics and Gynecology at NYU Langone ishonest, tells ishonest—so it's not all that surprising that a vaccine could initiate such a response.

Does this research tell us anything about the COVID-19 vaccine's effect on fertility?

One major concern regarding the COVID-19 vaccine has been among people looking to get pregnant—particularly that the vaccine would affect their fertility. The Centers for Disease Control and Prevention (CDC) have specifically stated that there's no evidence that the COVID-19 vaccine would cause issues with becoming pregnant at any point, and this new study adds more evidence to that claim.

What if your period changed in a different way following the COVID-19 vaccine?

Unfortunately, those answers doesn't exist right now—researchers said questions still remain around other possible changes to menstrual cycles like changes in menstrual symptoms, unscheduled bleeding, or the quality or quantity of menstrual bleeding.

One thing the study did help point out, however, is that perfectly regular cycles—ones that come exactly every 28 days, without fail, for example—are very rare, says Dr. Shirazian. And now, partly because of the COVID-19 vaccine, people may be watching their menstrual cycles more carefully. "All of a sudden, everyone is paying a lot of attention to their periods, and noticing what we already know: There is always some irregularity to the cycle," she says, citing what she calls observer bias. "You just notice [changes] more when you're really watching."

That said, if you're experiencing pain, heavy bleeding, or a period that's otherwise super out of whack, don't just chalk it up to baseline irregularity or the vaccine. Call your doctor—especially if you're among the women who've reported postmenopausal bleeding, as reported by the NYT. That can be a sign of endometrial or uterine cancer, according to the American College of Obstetrics and Gynecologists, and needs to be evaluated right away.

Read more on: menstrual, daily


What we do

We make skincare treatments and customize them for your skin-related problems, genetics, lifestyle, and environment.

How you benefit

You get total control over your skincare and the choice to change your skin. An impossible has just become possible.

How Custom Beauty Works

Desktop Mobile Graphic
Take the Quiz

Tell us about your skin, general health, lifestyle, environment, and all your skin goals. The quiz takes 4-8 minutes.

Outline of microscope
Create Your Treatment

Our algorithm creates a unique routine with a few customized products. The algorithm uses 50+ years of skincare research.

Outlines of Packaging
Divide and Rule

Every product is designed for one problem. Apply the product when the problem appears. Much like you treat flu or headache.

Product Values

A family sharing common values functions effortlessly and effectively. So do our products. All our products share these values.

Outline of bulb
Precise

Typical skincare routines confuse your skin with 20-50 ingredients. Our custom routines contain 1-8 ingredients, sending clear signals to your body to use the ingredients and recover faster.

Outline of Green Leaf
Concentrated

Our skin can use only active ingredients, also called actives. Most products contain up to 10% actives, whereas our products contain at least 90% actives. You get better value. Your skin avoids junk food.

Get Started

Never Used Before

Take the quiz below and discover a customized treatment for your unique skin-related problems, lifestyle, and environment.

Know Your Treatment

Every treatment has a unique 3-digit ID. You can find the ID on the product label. Search the ID on top right corner or click below.

Targeted Solutions

If a particular skin problem is bothering you, browse our products for your specific problem. You can customize your routine later.