How the COVID-19 Vaccine could Change your Menstrual Cycle

How the COVID-19 Vaccine could Change your Menstrual Cycle

By Maria Elena Garcia, Honeycomb Contributor

There is a reason why the menstrual cycle is considered a “vital sign” in clinical practice. If you menstruate, and go to a check-up, you will most likely  be asked when the first day of your last menstrual period occurred. Why does this matter? Because menstrual cycles and bleeding patterns respond to stress in our lives in a very unique way. Not only is the menstrual cycle responsible for alerting about a potential pregnancy, but it is an indicator of our health and well-being. Think about it, having a hard time balancing work, school, social life, partners, friendships, and all other caveats of human life put us under the type of stress that has us thinking it is normal to have skipped a period last month. Irregular bleeding is part of normal life for people who are dealing with hormonal contraceptives or any other external factor that affects our hormones. Beyond that, menstruation is a part of the gender and gender dysphoria experience in many trans men, trans masculine people, and the masculine center of genderqueer people. Because of these, and many other reasons, we use period tracking apps and google symptoms that start with the phrase “Is it normal if my period is____”. 


In early 2021, thousands of people who menstruate asked the question “Is it normal if my period is different after the COVID-19 vaccine?.”  The gaps in knowledge about how the menstrual cycle responds to the immune response of vaccines exist due to structural, cultural, and political decisions. Therefore,  there was no research to inform people about the vaccines’ potential effect. Instead, we turned to each other and asked “Wait, did you experience this too?” and felt a sense of relief when we knew we were not alone. 


Quickly, the dismissal of these menstrual change concerns by medical experts fueled politicians, wellness influencers, religious leaders, and pundits to link short-term menstrual changes with long-term fertility issues. The result was a greater doubt and hesitancy amongst vaccine-hesitant and anti-vaccine individuals towards the SARS-CoV-2 vaccine. Later, when the vaccine became available to adolescents, parents cited these same concerns fearing the disruption of their children’s development and saw it as a greater risk than the risk of becoming sick with COVID-19. 


The truth is simple if taken the time to explain. Inflammation (swelling) is part of our body’s immune response to a vaccine. Guess what is also an inflammatory response? Menstruation! Menstruation is the process of swelling and repairing the uterus and uterine system by shedding off the endometrium - which makes the external lining of the uterus. Just like running a marathon, prepping for the LSAT, or giving the most important pitch of your life leads to different hormone concentrations that affect the menstrual cycle, so does the short-term stressor of a vaccine response. And most importantly, the immune response of a vaccine is much more different than the long-term disruption to the menstrual cycle that COVID-19 invokes, especially to those with long COVID. 


In fact, this is not the only time that we hear about people experiencing menstrual changes after being vaccinated against something. The HPV, Typhoid, and Hepatitis B vaccine have their own studies about people experiencing menstrual changes. The COVID pandemic was able to highlight a gap in research regarding vaccine side-effects, like many other aspects of the health system. 


InJuly 2022, scientists at the University of Illinois published research, first in its kind about the effects of vaccines on menstrual cycles. The study found that a heavier menstrual flow was found in non-white Hispanic/Latinx older adults, those who had a reproductive condition such as PCOS and endometriosis, used hormonal birth control, have been pregnant, or experience fever and fatigue after the vaccine. One  main finding was the reporting of “breakthrough bleeding”. People who used LARCs, other hormonal contraceptives, or gender-affirming treatment that eliminates menstruation reported increased and/or unusual bleeding after their vaccine, no matter who the maker (e.g., Pfizer, Moderna, J&J) was.   


How is it, then, that over a year after the COVID-19 vaccine was available to the general public, we are just now seeing research come up about the side-effects  to our menstrual cycle? In reality, there is no protocol for looking at the menstrual cycle for vaccines other than for the purpose of making sure that the vaccine is safe for pregnant individuals. Additionally, the protocol for looking for side-effects usually does not extend past 7 days of closely monitored symptom reporting from the vaccine makers. The people in the study experienced these post-vaccine changes until a week after receiving their dose, meaning that there was no space for vaccine makers to take a look at these factors when developing a list of potential side-effects. 


Changes in bleeding patterns for menstruating people should not be dismissed by medical professionals, nor should they be considered part of normal life. Oftentimes, these changes can help providers learn where they come from. For example, there are research findings about epidurals and heavy bleeding for post-menopause individuals. Some of these people had to go through painful and expensive diagnostic procedures to address the source of their bleeding. Yet, this side-effect isn’t considered common knowledge, continuing the cycle of painful, and unnecessary diagnostic procedures. Not only that, but unexpected bleeding for trans men and the masculine genderqueer diaspora runs the risk of navigating public bathrooms or their workplace while bleeding, which can generate emotional distress and public harm. 


The truth is, we need this type of research to be part of common practice. Westernized cultural beliefs about menstruation and the uterine reproductive system are outdated, harmful, and bring shame. It should not be “break through” research to explore the way that many medications, vaccines, and treatments can affect the menstrual cycle. While this research is the first of its kind, we certainly hope that it does not become the last. 



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