When it comes to the differences between men and women, most of us could drum up a candid list of points. But the dissimilarities run far deeper than the obvious Venus vs. Mars stuff. In fact, research has shown that the differences between the two biological sexes extend as far as genetics and even affect our immune systems and rates of chronic disease. Here, experts explain why men and women may respond differently to everything from the common cold to vaccinations.

How Men’s And Women’s Immune Systems Differ

When it comes to the way men’s and women’s immune systems respond to infections, acute and chronic diseases, vaccines, and more, sex hormones play a huge role. 

“Generally speaking, estrogen (the female sex hormone) has been found to enhance the immune response, while testosterone (the male sex hormone) has been found to suppress the immune response,” explains Sanjeev Jain, M.D., board certified allergist and immunologist at Columbia Allergy. “It has also been noted that estrogens and testosterone activate different mediators of the immune system, so male and female immune systems likely respond differently to illness.” 

So what does that mean for everyday immunity? Allow us to explain.

5 Ways Men’s And Women’s Immune Differences Affect Their Health

Men’s and women’s hormonal differences impact their health (especially related to immune function) in a few key ways.

1. Fluctuations in Immune Reactivity

Research suggests that the fluctuating amounts of female sex hormones throughout the menstrual cycle impact their immune systems, while men enjoy a little more consistency. 

Read More: The All-Natural Guide To Surviving Your Period With A Smile

During menstruation, for example, estrogen and progesterone levels rise, which makes the immune system more active, explains Jain. “The enhanced function of immune system mediators may lead it to attempt to fight off anything found to be foreign in the body.” Basically, in this phase of the cycle, the immune system becomes slightly overactive (and overprotective), which can contribute to symptoms like feeling tired or under the weather. 

2. Susceptibility to Viruses

Meanwhile, levels of the stress hormone cortisol also tend to increase during menstruation, which can negatively impact the immune system and make women more susceptible to getting sick during that time, adds Vivek Cherian, M.D., an internal medicine physician with the University of Maryland Medical System.

3. Response to vaccinations

According to research published in the peer-reviewed journal Ann Ist Super Sanita, women have been found to mount a more significant response to vaccinations when compared to men, which essentially means they are more likely to feel crummy after getting the shot, notes Jain. Again, women’s higher estrogen levels seem to be behind this, though more research is needed to confirm.

Luckily, that not-so-fun initial response comes with a worthwhile payoff in that women may ultimately produce more antibodies than their male counterparts after getting vaccinated. This may support them in experiencing fewer symptoms or shortened length of illness, according to Jain. 

Since this advantage tends to be reduced with age (especially after menopause), it’s important for both sexes to get vaccinated against illnesses, especially as they get older, Jain urges. 

4. Likeliness to experience autoimmune conditions

While women’s increased immune system activity can be beneficial for their responses to vaccines and viral infections, it can also have some detrimental effects, particularly when it comes to autoimmune conditions, notes Jain. In fact, research published in Cureus has shown that women are more affected by autoimmune conditions than men. For example, the authors note that systemic sclerosis, which is a condition associated with tightening of the skin and joints, is four times more common in women than in men. 

5. Gut function

Research, including a recent study published in Gut Microbes, has shown that estrogen and testosterone both influence the healthy bacteria that grows in the gut, which is important considering an estimated 70 percent of the immune system is actually located there.

Read More: 6 Things We Do That Mess With Our Gut Microbiome

“Research published in the journal frontiers in Immunology has shown that estrogen can positively improve gut health through effects on the thickness of the gut lining and amount of mucus secretion, which help make the gut more resistant to injury,” Jain highlights. The same research also suggests that estrogens, in particular, promote the growth of good bacteria in the gut. 

The Bottom Line

All in all, immune system differences between the sexes are subtle and complex, though evidence suggests that women are more likely to fall ill or feel sick during menstruation and that they mount a more notable response to vaccinations. 

Of course, frequent illness concerning responses to vaccinations or other immune issues should always be brought to your healthcare provider’s attention and not written off as the fault of your hormones.