A person’s menstrual cycle may affect their immune system’s response, causing fluctuations throughout the month.

The menstrual cycle involves a series of changes in hormone levels and structures within the female reproductive system. It allows a person to become pregnant.

Sexual hormones, such as estrogen and progesterone, may play a role in regulating the immune system. This has led researchers to look more into how a person’s immune system responds throughout their menstrual cycle as these hormones are in flux.

It is likely that a person’s immune system response improves or weakens during different phases of the cycle.

This article reviews what the immune system does, how the different phases of the menstrual cycle may affect it, and tips on managing the immune system’s fluctuations.

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The immune system protects the body from foreign invaders and illness when functioning normally. Several organs, chemicals, cells, and proteins make up the immune system and work together to create a cohesive system.

People only notice their immune system if it weakens, is fighting a particularly strong infection, or is working improperly.

The immune system has three main functions:

  • find and suppress harmful substances from the environment
  • fight disease-causing germs, such as viruses, bacteria, fungi, or parasites
  • fight disease-causing changes in the body, such as cancer cells

It has two subsystems that work together to provide defense for the body: adaptive and innate. The adaptive system makes antibodies to fight specific invaders. The innate system creates a general defense against infection, creating cells such as the natural killer cells and phagocytes, which consume invading cells.

In some people, the immune system mistakenly attacks healthy tissue in the body. This is known as an autoimmune disorder. Examples include:

Some evidence suggests that sex hormones that fluctuate throughout the menstrual cycle may influence the immune system. In a healthy system, it may mean a person will go through periods of higher and lower infection resistance. People with autoimmune diseases may notice disease activity changes throughout the month.

During the follicular phase, the body primarily produces estrogen. Estrogen helps prepare the uterus for the implantation of a fertilized egg by thickening its lining. It also plays a role in the ovaries releasing an egg.

A 2022 systematic study and meta-analysis found evidence suggesting that 53 different cytokines, proteins that signal the immune system, fluctuate during the menstrual cycle. They note that levels of these molecules tend to be higher during the follicular phase compared to the luteal phase.

For people with typical immune systems, the follicular phase is likely stronger compared to the luteal phase. However, people living with autoimmune disorders may notice an increase in symptoms, often known as a flare or flare-up.

Ovulation occurs 14 days before ovulation. It occurs when the ovaries release an egg for fertilization.

Ovulation happens at the end of the follicular phase. Estrogen levels will generally remain high but then drop suddenly following ovulation. This may indicate that a person’s immune system response will remain higher until ovulation ends and the luteal phase begins.

Read more about ovulation.

During the luteal phase, estrogen levels drop and progesterone levels rise. This allows the body to prepare for the presence of a developing fetus.

It also means that a person’s immune system function decreases during this phase. According to the same 2022 study mentioned above, several substances of the immune system, including different antibodies and cytokines, dip during the luteal phase.

While this may make a person more susceptible to infection, it also may provide relief to people living with an autoimmune disorder that flares during the follicular phase.

Using progesterone-based birth control may also negatively impact the immune system. In a 2017 study, researchers noted that progesterone-based components suppress the immune system, particularly at mucus sites, such as the genitals, respiratory tract, and gastrointestinal (GI) tract.

The progesterone components bind to the receptors on various immune cells. This could cause a person to have a general reduction in their ability to fight off an infection. The researchers noted that this may have an impact on the overall health of anyone who uses hormonal birth control.

Read more about the menstrual cycle.

Menstruation occurs when the uterus sheds the lining built up during the follicular phase of the cycle. It comes at the end of the luteal phase and is associated with a drop in progesterone levels and a rise in estrogen levels.

An older study from 2011 noted that people living with an autoimmune disorder often develop worsening symptoms during menstruation due to fluctuations in hormone levels. In other words, the immune system is starting to get a boost during this time.

Read more about menstruation.

A person can take several steps to help boost their immune system. These include eating a healthy diet, regularly washing hands, and managing stress.

Eat a healthy and balanced diet

A healthy and balanced diet can help boost the immune system.

A person should emphasize eating the following foods:

  • fruits
  • vegetables
  • whole grains
  • lean protein
  • fat free or low fat milk and milk products

A person should also limit the amount of foods that contain high levels of:

  • salt
  • saturated fats
  • cholesterol
  • added sugars

Learn more about eating a balanced diet.


Exercise provides several benefits, including improving sleep, mood, and overall feeling better. Some evidence suggests that exercise may boost the immune system.

Learn more about exercise.


New evidence suggests that lack of sleep or poor quality sleep may negatively impact a person’s immune system. This may lead to the development of various conditions, such as heart disease, high blood pressure, and stroke.

Read more about why sleep is essential for health.


Keeping the hands clean throughout the day can help prevent the spread of microorganisms and help reduce the risk of becoming sick. A person should wash their hands after using the facilities, prior to eating, or before touching their face with their hands.

Read about proper handwashing.

Minimize stress

Evidence suggests that psychological stress plays a role in changing how the immune system responds to different infections. Reducing stress through exercise, therapy, or other means may help prevent changes to how the immune system responds.

Learn more about stress-reduction strategies.

Evidence suggests the immune system’s functions fluctuate during the menstrual cycle with the rise and fall of estrogen and progesterone. This may have important implications for a person’s susceptibility to illness and people living with autoimmune disorders who may notice their symptoms worsen during the luteal phase.

A person can take steps to help boost their immune system. These can include reducing stress, exercising, eating well, and improving sleep quality.