{"id":19488,"date":"2022-01-14T16:02:12","date_gmt":"2022-01-14T21:02:12","guid":{"rendered":"https:\/\/thepapergown.zocdoc.com\/?p=19488"},"modified":"2026-08-14T10:22:53","modified_gmt":"2026-08-14T15:22:53","slug":"how-the-covid-19-vaccine-might-impact-your-period","status":"publish","type":"post","link":"https:\/\/www.zocdoc.com\/blog\/guides\/how-the-covid-19-vaccine-might-impact-your-period\/","title":{"rendered":"How The COVID-19 Vaccine Might Impact Your Period"},"content":{"rendered":"

When Amelia*, 25, received her first dose of the Pfizer COVID-19 vaccine in March 2021, she was elated. But a few weeks later, as she anxiously awaited her typically regular period, she became more and more confused.\u00a0<\/span><\/p>\n

“After it was two days late, I began to worry and even bought two pregnancy tests,” she says. “<\/span>They were negative, but it was freaking me out. <\/span>I even talked to a doctor via telehealth to see if I needed to get any blood work done to verify that I was not indeed pregnant.”<\/span><\/p>\n

After nine anxious days, she finally got her period.<\/p>\n

Now we know that Amelia’s delayed period was likely a side effect of her vaccine. New research confirms<\/a> her and others’ experiences \u2014 and experts urge patients to remain calm about any of their flow woes.\u00a0<\/span><\/p>\n

In 2020, as more and more people like Amelia came forward with stories about <\/span>post-vaccine<\/span> irregularities in their menstrual cycles, t<\/span>he National Institutes of Health<\/a> granted funds to five major institutions to investigate. One of the first studies<\/a> to come out,<\/span> recently published in the journal Obstetrics & Gynecology, concludes that the COVID-19 vaccine can cause small, temporary changes in the length of menstrual cycles.\u00a0<\/span><\/p>\n

Experts say the study is validating. It indicates that while doses of the vaccine (either Pfizer, Moderna or Johnson & Johnson) might cause minor changes in cycle length, it doesn’t pose danger for people who menstruate and has <\/span>no impact<\/span><\/a> on fertility.\u00a0\u00a0<\/span><\/p>\n

But the study\u2019s authors note that <\/span>more research<\/span><\/a> is needed on how the vaccine can affect associated symptoms, like cramps, and levels of bleeding. Additionally, the study isn\u2019t necessarily representative of the general population; it analyzed data from people<\/a> who were predominantly white and didn\u2019t use hormonal contraceptives. <\/span>Amelia, for instance, had been off hormonal birth control for several years.<\/p>\n

Dr. Natalie Crawford, MD<\/span><\/a>, a gynecologist in Austin, Texas, clears up questions about how a shot in the arm can even impact menstruation:<\/span> \u201cA period is shedding of the endometrium (the lining of the uterus).\u201d That tissue hosts a range of immune cells, she says.<\/span><\/p>\n

“It is possible that when the body has a large immune response, like making COVID-19 antibodies either from a COVID-19 infection or the COVID-19 vaccine, it may make the endometrium unstable and cause changes in bleeding,\u201d Crawford explains. \u201cWe also see period changes from chronic illness, stress, ovulation disorders or other medical issues.\u201d\u00a0<\/span><\/p>\n

At the time of her period confusion, Amelia had no way to put two and two together. Her doctor didn’t mention that delayed menstruation could be a post-vax side effect. R<\/span>esearchers also hadn’t yet properly looked into the issue.
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“Although this would not have impacted my decision to get the vaccine, I do wish I had known that it could affect [menstrual cycle] timing beforehand,” Amelia says. “It would have saved me an anxious week thinking, and the cost of that telehealth visit and pregnancy tests.”<\/span><\/p>\n

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*Amelia’s name has been changed for privacy.\u00a0<\/em><\/p>\n

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