It is a myth that the COVID-19 vaccine makes hormonal contraception less effective. However, certain vaccines may slightly increase the risk of a blood clot, a serious but rare side effect of some hormonal birth controls.

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According to the Centers for Disease Control and Prevention (CDC), healthcare professionals have administered 18.5 billion doses of the Johnson & Johnson’s (J&J) Janssen vaccine in the United States. Of this total, just 59 people have reported blood clots. This means the actual increase in blood clot risk is incredibly small.

While the vaccines do not affect hormonal contraception’s effectiveness, some people have reported temporary changes in their menstrual periods after getting the vaccine. Researchers do not know why this is or whether it has links to the COVID-19 vaccine. Additionally, it is unclear how other factors, such as social and lifestyle changes or having COVID-19, can change a person’s periods.

People who use natural family planning and other methods that rely on cycle tracking may find it more difficult to pinpoint ovulation and avoid pregnancy.

Read more about how the COVID-19 vaccines may affect birth control, fertility, blood clot risk.

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According to the nonprofit Planned Parenthood, there is no evidence that the COVID-19 vaccine makes birth control more or less effective. However, as of March 2022, no studies have directly tested this.

There are currently no widespread reports from either vaccine recipients or clinical trial participants claiming that their birth control stopped working after getting a vaccine. Similarly, there have been no claims of increases or decreases in fertility.

None of the COVID-19 vaccines contain hormones, or any ingredients that scientists know are likely to affect a person’s hormones. Additionally, its contents remain in the body for a short period.

Some vaccine recipients report that their periods changed after getting the shot.

This includes periods that are early or late or lighter or heavier than usual. Researchers do not yet know what might explain this change, but some scientists are starting to investigate the link.

A retrospective study published in 2021 found that about half of the individuals who menstruate experienced a change in their periods after getting the vaccine. While most of the participants were not using hormonal contraception, those taking it were slightly more likely to report changes in their cycles.

The study’s authors say their research may overreport the actual rate of period changes. This is because of selection bias — the researchers sent surveys to people after their vaccinations, so participants whose periods changed were more likely to respond to their survey.

While reports of menstrual cycle changes are relatively widespread, they do not affect how well a person’s birth control works.

They can, however, make it harder to track a person’s cycles. People who use natural birth control, such as the fertility awareness method, may find it difficult to know when they are ovulating. This birth control method is less effective at preventing pregnancy.

Learn more about ovulation and how to identify it here.

Some blogs and social media accounts claim that the COVID-19 vaccine can affect fertility. However, there is no evidence to support this claim, and in fact, there is plenty of evidence showing the opposite.

In a 2022 study, researchers assessed the effect of the COVID-19 vaccine on 2,126 people who self-identified as females. The participants filled in a questionnaire every 8 weeks that asked about their lifestyle, their health, and their partners.

The survey found no difference in the fertility of those who chose vaccination and those who did not.

However, the study found that males who contracted COVID-19 saw a temporary decrease in fertility. This suggests that the vaccine is a good choice for people hoping to get pregnant because it reduces their chance of getting COVID-19 and has no apparent effect on their fertility, unlike the disease.

In a 2021 review of scientific reviews, researchers found no evidence suggesting the COVID-19 vaccine could adversely impact male fertility. However, some evidence showed that having COVID-19 infection could affect male fertility.

The authors explain that the virus’s spike protein uses angiotensin-converting enzyme 2 (ACE-2) receptors to enter cells. ACE-2 is present at high rates in the cells that make sperm cells, meaning the virus may be able to adversely affect these cells. It is also present in the ovaries, uterus, and vagina. Theoretically, this means COVID-19 could affect fertility, but research has not yet shown this to be true.

It is important to note that doctors do not diagnose infertility until a person has been trying to get pregnant for at least 12 months. Because researchers are just starting to understand how COVID-19 affects fertility, they cannot make a connection between the virus and infertility.

Learn more about infertility in males and females here.

There is no evidence that the vaccine is dangerous to anyone except people who are allergic to ingredients in the vaccine. The CDC recommends vaccination for everyone over the age of 5.

The main safety concern related to contraception is a slight increase in birth control risk.

According to the CDC, a small number of some vaccine recipients have experienced a rare but dangerous blood clot. The J&J Janssen vaccine, in particular, slightly increases the risk of a blood clot called thrombosis with thrombocytopenia syndrome (TTS).

While these instances are very rare, they a worth noting as some hormonal birth controls also raise a person’s risk of blood clots.

Learn more about the symptoms of a blood clot here.

Hormonal birth control can increase the risk of getting a blood clot, usually in the leg. A clot can break loose and travel to the lungs, which can be potentially life threatening.

Certain risk factors, such as smoking and having obesity, may further raise a person’s risk.

Hormonal contraceptives may increase the number of people dying from blood clots each year by 300–400. Researchers believe this may be due to the hormone estrogen found in birth control pills, as estrogen increases clotting factors in the blood.

Learn more about the link between blood clots and birth control here.

People who have questions about birth control and COVID-19 vaccinations might want to talk with a doctor.

They may also want to contact a doctor if:

  • they have concerns about their period, with or without a COVID-19 vaccine
  • they develop serious vaccine side effects
  • they want help choosing which vaccine is best for them
  • they are reluctant to get a COVID-19 vaccine
  • they think they might be pregnant
  • they want an alternative to hormonal birth control.
  • they think they might have a blood clot

It is safe to use all forms of birth control and get a COVID-19 vaccine. Some people who use birth control and have a high risk of blood clots, such as people who smoke, may wish to discuss switching birth control methods with a doctor.

People who are trying to get pregnant or who use calendar and tracking-based methods to monitor fertility should know their cycles may temporarily change following vaccination.