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Noticed Changes in Your Menstrual Cycle After COVID Infection or Vaccination?

Updated: Aug 9, 2021

Have you noticed changes in your menstruation following a COVID-19 infection or vaccination? If yes, you’re not alone.

Women around the world are reporting changes in their menstruation cycle, flow, and discharge after contracting COVID-19 or after a COVID-19 vaccination. As with many problems surrounding women’s health, there has been little clinical research into why COVID-19 affects menstruation cycles. So, for this blog, we are largely relying on personal accounts from women.

It is important to note that while women may be experiencing changes in their menstrual cycles, there has been no research to suggest a COVID-19 infection or vaccine will cause changes to fertility.

COVID-19 Infection & Menstruation:

There has only been one clinical study on the effects of a COVID-19 infection on menstruation cycles. The study was conducted in China and analyzed the menstrual data of 177 women of childbearing age who had previously been diagnosed with COVID-19. The study found that 25% of women experienced changes in their menstrual volume levels, 28% of patients had menstrual cycle changes. Most commonly, the women experienced a prolonged cycle and decreased volume of flow.

Interestingly, the study found that the more severe the COVID-19 infection, the more changes in the menstruation cycle. For women with very severe COVID-19 infections, they were more likely to experience prolonged periods- 34% of severely ill patients had cycles longer than 37 days.

In follow-up, the researchers found that 84% of patients resumed a normal menstrual volume and 99% of patients returned to their normal cycle within 1-2 months. This suggests whatever changes COVID-19 is causing in women are only temporary and resolved in a relatively short period.

Medical News Today interviewed 6 women with chronic COVID who experienced changes to their menstrual cycles. The women reported irregular periods, unusual clotting in period blood, and worsened symptoms of premenstrual syndrome (PMS). Several of the women experienced unusually large blood clots and an increased amount of clots in their period blood. One woman, whose periods had ceased due to hormonal birth control, reported her period returning for the first time in 10 years. Another woman has since developed anemia due to her increased volume of blood during her period.


Some doctors speculate that changes in menstrual cycles following a COVID-19 infection may be caused by increased stress. It is not uncommon for women who have anxiety, PTSD, life-stressors, or have experienced other chronic diseases to have changes in their menstrual cycles.

But other doctors theorize that COVID-19 could potentially impact female reproductive organs. Little research has been done on this topic, but theoretically, the virus could attack ovarian function given how COVID-19 has been shown to affect other organs.

We also know that COVID-19 affects men and women differently- due to the immune effects of estrogen. One study found that the cellular immune response in Hepatitis B and C infections may cause abnormal ovarian function- given the immune systems regulatory role in ovarian development and ovulation. When the immune system is damaged, it is likely that ovarian function will also be altered.

Our Theory:

In a previous blog, we discussed how COVID-19 can cause mitochondrial damage, which leads to symptoms of chronic COVID. Mitochondrial damage has also been demonstrated to express itself in reproductive organs. Increased mitochondrial damage will lead to uterine dysfunction. Some doctors theorize that endometriosis, the excessive growth of endometrial cells in the uterus, is caused by mitochondrial damage.

The mitochondria play an essential role in the creation of female sex hormones. In turn, these hormones are able to modulate mitochondrial function. Damage to mitochondria will cause fluctuations in estrogen production, which will have altering effects on menstruation.

Mitochondrial damage will also effect the production of thyroid hormones. Thyroid hormones affect more than just metabolism. These hormones also influence the production of other hormones including estrogen and progesterone which can cause irregular cycles, skipped periods and heavy periods. Studies have also shown that COVID triggers systemic immune activation that can actually cause inflammation in the thyroid gland itself. This will result in low thyroid function.

Our theory is that the changes in menstruation following a COVID-19 infection are at least in part due to mitochondrial damage. This would explain why, in the Chinese study, women with more severe COVID-19 infections experienced more changes to their menstruation cycles. A more severe infection would lead to more mitochondrial damage, which would in turn have an increased effect on menstrual cycles.

COVID-19 Vaccine & Menstruation:

Unfortunately, no studies have been published on the effects of the COVID-19 vaccine and menstruation. However, one study by the University of Illinois is currently collecting survey responses from vaccinated women on the topic. Click here to fill it out!

Given the lack of research, we only have personal accounts to describe changes to period cycles following vaccination. Some women have reported changes in cycle such as mid-cycle bleeding, period flow, and more painful cramping. Other women have experienced periods for the first time in years after hormonal birth control caused it to stop.


Given the connection between the immune system and the menstrual cycle, it is likely that when your immune system responds to the COVID-19 vaccine, there will be some changes in the menstruation cycle. It could also again be a reaction to stress. The vaccine also causes inflammation for some people, demonstrated in mild, flu-like symptoms. Inflammatory cells can potentially modulate estrogen response, which would cause heavier periods.

While it can be scary to experience changes to menstruation following an illness or vaccination, it is important to keep in mind that menstruation cycles are easily impacted by daily stressors and other factors. There has also been no evidence of lasting effects or changes to fertility from COVID-19 or the vaccine.

The Johnson Center for Health services patients in-person in our Blacksburg and Virginia Beach / Norfolk locations. We also offer telemedicine for residents of Virginia and North Carolina!


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