Your Immune System Takes a Hit During Your Period Here’s Why

Mood swings, bloating, and cravings? Sure, you expect those with your period. But if you also find yourself fighting off sniffles, fatigue, or feeling oddly flu-like during your cycle, you’re not imagining things. Your immune system really does take a hit around that time of the month.

As if dealing with PMS wasn’t enough, research shows hormonal fluctuations throughout the menstrual cycle can affect how well your immune system functions. So yes feeling a bit more rundown during your period is biologically valid.

How Your Menstrual Cycle Affects Immunity

The immune system and reproductive hormones are deeply interconnected. According to Ashanda Saint Jean, MD, OB/GYN and associate professor at New York Medical College, shifts in estrogen and progesterone can subtly but significantly change how your body responds to infection.

• After ovulation, rising progesterone levels help prepare your body for a potential pregnancy. But progesterone also has immunosuppressive properties, which may lower your immune defense, per a 2023 review in Archives of Gynecology and Obstetrics.

• Around the same time, estrogen spikes can trigger histamine release, leading to flu-like symptoms such as nausea, fatigue, and dizziness. This is sometimes called the "period flu" and it’s very real.

• For those with chronic health conditions like asthma, symptoms may worsen during this hormonal phase. Up to 40% of people with asthma report increased flare-ups before their period, according to a 2016 review in Multidisciplinary Respiratory Medicine.

It’s worth noting that not everyone is affected the same way. But if you consistently feel sick or get actual colds around your period, it’s worth paying attention and bringing it up with your healthcare provider.

5 Ways to Support Your Immune System During Your Period

While you can’t stop hormone fluctuations, you can support your immune health to feel stronger and more balanced throughout your cycle.

1. Eat nutrient-rich, anti-inflammatory foods
   Leafy greens, berries, nuts, seeds, and fatty fish are packed with antioxidants and fiber that promote immunity. Bonus: calcium-rich foods (like leafy greens and fortified milk alternatives) may also help ease PMS symptoms like anxiety and bloating.

2. Get consistent, quality sleep
   Lack of rest can leave your immune system struggling. Aim for at least 8 hours a night, especially in the days leading up to your period. Gentle wind-down routines like meditation or stretching can help you fall asleep more easily when hormones are making it tough.

3. Move your body gently if needed
   Regular exercise helps regulate hormone levels and reduce PMS symptoms, including period flu fatigue. Try low-impact activities like walking, Pilates, or yoga if you’re feeling sluggish.

4. Lower your stress levels
   Chronic stress can suppress immune function and make PMS feel even worse. Whether it’s journaling, deep breathing, or simply stepping away from screens for a bit, find moments to check in with yourself and decompress.

5. Talk to your doctor if symptoms are severe
   If you regularly get sick during your cycle or experience extreme symptoms like severe cramps, mood swings, or heavy bleeding talk to your provider. They may suggest hormonal birth control or other strategies to help stabilize your symptoms.

What Is Period Flu, Really?

"Period flu" isn’t a medical diagnosis, but it’s a common way to describe the body aches, fatigue, GI upset, and malaise some experience before menstruation. It stems from the hormonal shifts that impact your immune and nervous systems not an actual virus. Still, it can feel just as intense.

Why You Might Get Sick More Often Before Your Period

While most adults get 2–3 colds per year, getting sick every month could point to something more. Frequent illness may signal low immunity due to stress, poor sleep, a nutrient deficiency, or another underlying condition. If your cycle consistently aligns with illness, it’s worth investigating.

Can Being Sick Delay Your Period?

Yes. Illness especially something like the flu or a stomach virus can affect your cycle. The stress your body undergoes when fighting infection may temporarily disrupt hormone production, delaying or even skipping a period. One missed period isn’t usually cause for concern, but repeated irregularities are worth a check-in with your healthcare provider.

Know Your Cycle, Support Your Health

Understanding how your cycle affects your immune system gives you the power to better support your body not just during your period, but throughout the month. Small shifts in routine like adding anti-inflammatory foods or scheduling extra rest can make a big difference.

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