You may have heard that the COVID-19 vaccine can cause changes in menstruation. This could be a troubling side effect for people living with endometriosis, a condition often linked to painful periods and other menstrual symptoms. Researchers in public health and reproductive health have been exploring how this interaction may affect people with endometriosis.

COVID-19 vaccines are monitored carefully for safety, and clinical trials and retrospective studies show no higher risk of side effects for people with endometriosis compared to others. Some early, small studies suggested a possible link between the vaccine and worsening endometriosis symptoms. However, more recent larger studies don’t show the same association with worsening symptoms.

Continue reading to learn more about the effects of the COVID-19 vaccine and endometriosis.

Can the COVID-19 Vaccine Worsen Endometriosis Symptoms?

Current evidence suggests that COVID-19 vaccines may cause some temporary menstrual changes, like heavier bleeding or more cramps, for people of reproductive age. A 2024 systematic review of 61 different studies found that people often experienced at least one menstrual change in the cycle post-vaccination, including:

• Heavier or lighter bleeding than usual
• Changes in period length
• Dysmenorrhea (stronger menstrual pain)
• Unexpected intermenstrual bleeding (breakthrough bleeding)

Although menstrual changes can happen after the COVID-19 vaccine, these side effects are temporary and mild for most people. However, these side effects can be troublesome for people who already have menstrual disorders, such as endometriosis. Many of these potential COVID-19 side effects are similar to endometriosis symptoms, including painful periods and excessive menstrual bleeding, which can be severe.

Additionally, some side effects of the COVID-19 vaccine may be similar to endometriosis symptoms, such as fatigue (extreme tiredness), muscle or joint pain, or nausea. If you’re experiencing COVID-19 vaccine side effects, it may feel like these endometriosis symptoms are temporarily worse.

A 2024 systematic review and meta-analysis in Reproductive Sciences combined results from four studies with more than 2,200 women to evaluate the effect of COVID-19 vaccines in those with endometriosis. Researchers found that there wasn’t an increased risk for worsening endometriosis symptoms after two doses of an mRNA vaccine for COVID-19 (such as the Pfizer and Moderna COVID-19 vaccines). However, there was a small but temporary increase in menstrual pain in the endometriosis control group (those with the condition).

Researchers aren’t sure why menstrual cycle changes may occur after a COVID-19 vaccine. It’s thought that menstrual changes may be linked to immune response and temporary inflammation after vaccination.

Can the COVID-19 Vaccine Affect Fertility?

Infertility (difficulty becoming pregnant) can be a complication of endometriosis.

There is no evidence that the COVID-19 vaccine or an infection with the coronavirus that causes COVID-19 is associated with fertility problems. Several studies have found that people have the same chance of getting pregnant after a COVID-19 vaccine or COVID-19 infection as those who have not been vaccinated or infected.

While the COVID-19 vaccine may cause temporary changes in menstrual cycles, current research hasn’t found any lasting effects on fertility. The COVID-19 vaccine is considered safe and effective for people who are or want to become pregnant.

Does the COVID-19 Vaccine Interact With Any Endometriosis Treatments?

There are no known drug interactions between the COVID-19 vaccine and medications used to treat endometriosis. Early in the COVID-19 pandemic, health experts wondered if nonsteroidal anti-inflammatory drugs (NSAIDs) — a type of pain reliever often used for endometriosis-related pain — may interact with the COVID-19 vaccine. However, recent evidence shows that taking NSAIDs doesn’t weaken the immune response to COVID-19 vaccines. If you use NSAIDs to manage endometriosis pain, these medications are unlikely to interact with the vaccine.

Research suggests that some endometriosis treatments may reduce the risk of menstrual changes following a COVID-19 vaccination. A 2024 study in the journal Women’s Health explored the effect of the COVID-19 vaccine on women with endometriosis. Researchers found those taking hormonal therapies experienced fewer menstrual symptoms after the COVID-19 vaccine compared to those not on hormonal therapies. This protective effect was observed across different types of hormonal therapies.

If you’re concerned about drug interactions with the COVID-19 vaccine, your health care provider or pharmacist can review your medications for potential interactions before you get the vaccine.

For those planning endometriosis surgery, you may wonder about the timing of the COVID-19 vaccine. According to the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP), current, recent, or upcoming surgery is not a reason to avoid vaccination. However, surgery can temporarily suppress your immune system, so a health care provider may recommend extra precautions if you have had, or are planning, a surgery or hospital stay.

Does Endometriosis Increase Your Risk of COVID-19?

Endometriosis can cause a state of inflammation throughout the body. Because of this, there was initially worry that endometriosis may increase a person’s susceptibility to the coronavirus that causes COVID-19. However, a 2024 review of 39 studies found no higher risk of COVID-19 infection for people with endometriosis compared to those without it.

Although endometriosis itself doesn’t seem to increase COVID-19 risk, the condition is associated with other health conditions that can, such as:

• Asthma
• Autoimmune conditions
• Certain cancers, such as breast and ovarian cancer
• Depression

Talk to your health care provider about how your specific health factors may affect your risk of COVID-19.

What Are the Risks of COVID-19 and Endometriosis?

People with endometriosis may have an increased risk of developing long COVID. Long COVID is a chronic (long-term) condition that some people experience after a COVID-19 infection. A 2023 study in the American Journal of Obstetrics & Gynecology found that women with a history of diagnosed endometriosis were 22 percent more likely to develop long COVID compared to those without.

Additionally, some long COVID symptoms can overlap with endometriosis symptoms, such as fatigue, diarrhea, constipation, and changes in your menstrual cycle. These shared symptoms can make it hard to know which condition is causing specific symptoms.

Having COVID-19 or long COVID may also make you feel worse overall while you’re sick. A MyEndometriosisTeam member shared, “I’m just getting over having COVID-19. Of course, it kicked up endo symptoms and period, so I was bleeding heavily and in pain.”

COVID-19 Vaccine Recommendations

There aren’t any specific clinical guidelines regarding the COVID-19 vaccine and people with endometriosis. Without specific recommendations, those with endometriosis should follow recommendations for the general public. The CDC recommends that everyone receive the 2024-2025 COVID-19 vaccine. It’s important to get the most recent version of the COVID-19 vaccine, even if you’ve been vaccinated in the past or have had COVID-19.

The COVID-19 vaccine can help prevent infection with the coronavirus and reduce the risk of serious complications, such as hospitalization and death. It may also help prevent long COVID symptoms. Since their introduction, research has consistently found that COVID-19 vaccines are a safe and effective way to build protection from the virus that causes COVID-19.

Talk to your health care provider about the benefits and potential risks of a COVID-19 vaccine.

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Did your endometriosis symptoms worsen or improve after you had COVID-19 or the COVID-19 vaccine? Share your thoughts and tips in the comments below or by posting on MyEndometriosisTeam.