Can Hepatitis B Vaccine Affect Menstruation?

Hormonal changes, drugs, chronic diseases are some of the reasons for pathological changes in menstruation. Some of these elements may result in heavy periods, while others may cause missed periods.

Although the influence of drugs, hormones, diseases on the menstruation cycle is well understood, it appears that people tend to overlook some other factors.

It seems that it is not rare to have mild menstrual changes post-vaccination. Women report changes in their periods after various vaccines like there have been reports of such changes due to Covid-19 vaccines. Studies also appear to show that hepatitis B may also affect the menstruation cycle [1], [2].

There is good news, too, as studies show any changes in menstruation post-vaccination are generally short-lived and do not require medical attention in most cases.

Hepatitis B Infection: Who is at risk? Who should get vaccinated?

Viral hepatitis is not rare and is a considerable health problem. There are many types of viral hepatitis (inflammatory diseases of the liver due to viral infections). Hepatitis A and E are mainly transmitted through contaminated food and water. Whereas hepatitis B, C, and D are primarily transmitted through contaminated blood and body fluids [3].

Thus, hepatitis B can also be transmitted sexually. Another common cause could be sharing needles. People in certain professions like those frequently coming in contact with human blood products may be at risk, too.

Thankfully, due to regular vaccination of high-risk individuals, hepatitis B is not very common. Nevertheless, it is a relevant disease. Data shows that about 21 to 22000 people get infected with the condition in the US each year, which is still a significant number [4].

In some, it may cause self-limiting acute illness, but in many, it may become a chronic, life-threatening disease. In addition, it may cause extensive scarring of the liver in some (liver cirrhosis). It may also increase the risk of liver cancer considerably.

Fortunately, a highly effective vaccine is available for the condition. In the US, people first get vaccinated by it at birth, followed by few booster doses. However, adults may often fail to get vaccinated or get booster doses in a timely manner.

Therefore, CDC strongly recommends high-risk individuals like those with multiple sexual partners, drug users, people going through dialysis, and so on to get vaccinated for hepatitis B as per recommendations [5], [6].

Hepatitis B Vaccine, Side Effects, and Effects on Menstruation

Fortunately, the hepatitis B vaccine is relatively safe and rarely causes any side effects. Some of its typical side effects are pretty mild and short-lived.

Thus, in some, it may cause soreness or swelling at the site of injection. Few individuals may develop a low-grade fever, body aches, headache after vaccination. Although rare, there is also a risk of allergic reactions in some.

Studies show that the hepatitis B vaccine might affect menstruation, and such adverse effects used to be quite common. However, it appears that modern vaccines rarely cause any such effects on menstruation. It may explain why some of the reputed websites like that of CDC do not mention such side effects [7].

How common are menstrual changes after the hepatitis B vaccine?

Despite the deficiency of data on the subject, it appears that menstruation changes after the hepatitis B vaccine used to be quite common. In one of the safety studies in Japan (phase 1 trial) in the 1980s, seven out of sixteen vaccinated women reported changes in menstruation [2].

However, such frequent changes in menstruation are not reported from trials carried out in the 21st century. It is because modern vaccines are produced using a very different kind of technology.

What kind of menstrual changes to expect after the hepatitis B vaccine?

Although data on the subject is too little to make any definitive conclusions, it appears that menstrual changes post hepatitis B vaccine are challenging to predict. In the Japanese study, there were reports of hypomenorrhea, oligomenorrhea, poly-menorrhea. Thus, in some women, hepatitis B vaccine may delay menstruation, while in others, periods may become heavier and shorter [2].

However, it is worth noticing that all vaccines differ from each other in purity and technology used. Most studies reporting menstrual changes after hepatitis B vaccination are either old (before the year 2000) or small sample size (few participants in the study).

It appears that most modern hepatitis B vaccines may not cause significant changes in menstruation. It is because early hepatitis B vaccines were plasma-derived (antigen derived from human plasma, and thus probably containing hormonal and other impurities) and had high levels of contaminations. Newer vaccines use entirely different technology and are much safer.

Why may vaccines like hepatitis B cause menstruation changes in some?

It is one of the challenging and poorly understood questions. Some researchers believe that such adverse effects reported from older vaccines were due to impurities. However, since modern vaccines are devoid of any such impurities, they do not appear to cause changes in menstruation.

Some researchers have also proposed other underlying mechanisms causing menstrual changes. Womb lining is rich in immune cells, and all vaccines have some kind of immune-modulating action. Therefore, these changes in immunity may also affect menstruation in one way or another.

After vaccination, there are lots of chemical signals generated in the body. These chemical signals are quite complex for science to interpret. Nevertheless, these chemical signals may also cause changes in menstruation.

Finally, there is good news, too. It appears that menstrual irregularities post-vaccination are short-lived, quite like fever or body aches.

Further, various healthcare agencies warn that these mild discomforts are not a reason to refuse from hepatitis B vaccine. It is essential to understand that the benefits of the vaccine are far greater.


  1. Covid vaccine: Period changes could be a short-term side effect. BBC News. Published May 12, 2021. Accessed July 29, 2021.
  2. Shingu T, Uchida T, Nishi M, et al. Menstrual Abnormalities after Hepatitis B Vaccine. The Kurume Medical Journal. 1982;29(3):123-125. doi:10.2739/kurumemedj.29.123
  3. What Is Viral Hepatitis? | NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases. Accessed July 29, 2021.
  4. CDC. Hepatitis B FAQs for Health Professionals | CDC. Centers for Disease Control and Prevention. Published December 30, 2020. Accessed July 29, 2021.
  5. CDC. Hepatitis B – Vaccination of Adults | CDC. Centers for Disease Control and Prevention. Published December 16, 2020. Accessed July 29, 2021.
  6. Birth-18 Years Immunization Schedule | CDC. Published June 16, 2021. Accessed July 29, 2021.
  7. Safety Information for Hepatitis B Vaccines | Vaccine Safety | CDC. Published September 9, 2020. Accessed July 29, 2021.
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