Understanding What are the flu like symptoms before your period?

September 23, 2025 •

5 min read

It's estimated that over 90% of people who menstruate experience some form of premenstrual syndrome (PMS). For some, this includes flu-like symptoms, a phenomenon commonly called “period flu,” which can feel like coming down with an illness right before your menstrual cycle begins.

Quick Summary

Feeling under the weather with symptoms like fatigue, headaches, body aches, and even chills before menstruation is known as “period flu,” which is linked to hormonal shifts, particularly the drop in progesterone, rather than a viral infection.

Key Points

Hormonal Fluctuations: The main cause of period flu symptoms is the cyclic change in hormones, especially the drop in progesterone before menstruation.
Prostaglandin's Role: These hormone-like compounds trigger uterine contractions but can also cause systemic inflammation, leading to widespread body aches and nausea.
Not Contagious: Unlike influenza, "period flu" is not caused by a virus, so it cannot be spread to others.
Common Symptoms: Fatigue, headaches, muscle aches, nausea, and digestive issues are frequent symptoms.
Timing is Key: Period flu symptoms are cyclical, appearing before menstruation and resolving shortly after it begins, helping distinguish it from an actual illness.
Symptom Management: Over-the-counter pain relievers, moderate exercise, heat therapy, and a healthy diet can help alleviate discomfort.

The 'Period Flu' Explained: Symptoms Beyond Typical PMS

Many people are familiar with the classic symptoms of premenstrual syndrome (PMS), such as bloating, mood swings, and cravings. However, some experience a more severe array of physical symptoms that closely mimic the influenza virus. This collection of symptoms has earned the informal name "period flu" among many who experience it, capturing the feeling of being genuinely unwell in the days leading up to their period. It is crucial to understand that despite the name, period flu is not contagious and is not caused by a virus. Instead, it is a hormonally-driven condition that can make regular activities feel difficult or impossible for a few days each month.

Common Flu-Like Symptoms Associated with Your Cycle

The symptoms of the so-called period flu can differ significantly from person to person and even from cycle to cycle. While typical PMS might involve irritability and cramps, the period flu often includes a more comprehensive set of physical discomforts. These can begin shortly after ovulation and typically resolve within a few days of menstruation starting. Common symptoms include:

Fatigue and Lethargy: A profound and unusual tiredness can set in, making it difficult to get out of bed or stay productive.
Muscle and Joint Aches: Widespread aches and pains throughout the body, similar to those experienced during a viral illness.
Headaches and Migraines: Hormonal headaches are common and can range from a mild, persistent ache to a severe, debilitating migraine.
Nausea or Digestive Issues: Upset stomach, nausea, diarrhea, or constipation can all be part of the premenstrual experience.
Low-Grade Fever or Chills: Some individuals may experience a slight increase in body temperature, along with hot flashes, chills, or sweats.
Brain Fog: Difficulty concentrating, forgetfulness, and general mental cloudiness can occur as part of this premenstrual phase.

The Hormonal Reasons for Your Symptoms

The exact cause of period flu is not fully understood, but it is strongly linked to the dramatic hormonal fluctuations that occur during the menstrual cycle. After ovulation, if pregnancy does not occur, levels of the hormones estrogen and progesterone drop significantly. This hormonal decline is a major catalyst for the symptoms experienced during the premenstrual phase.

The Role of Prostaglandins

One of the key players in this process is a group of hormone-like lipids called prostaglandins. Before and during your period, the lining of the uterus produces prostaglandins to trigger muscle contractions that help shed the uterine lining. However, if excess prostaglandins are released into the bloodstream, they can cause systemic inflammatory responses throughout the body. These inflammatory effects can lead to many of the flu-like symptoms, including muscle aches, headaches, and digestive upset like nausea and diarrhea.

Serotonin Level Changes

Fluctuations in serotonin, a neurotransmitter that helps regulate mood, sleep, and pain, are also believed to contribute to some period flu symptoms. The drop in estrogen can impact serotonin levels, which may lead to mood swings, sleep disturbances, fatigue, and an increased sensitivity to pain.

Period Flu vs. The Actual Flu: A Clear Comparison

Distinguishing between period flu and the actual influenza virus is important. While some symptoms overlap, there are clear differences in their cause, duration, and associated signs. Tracking your symptoms over several cycles can help you identify if your flu-like feelings are part of your regular menstrual pattern or something more serious.


Feature	Period Flu (Hormonal)	Actual Flu (Viral)
Cause	Hormonal fluctuations and prostaglandins	Influenza virus
Contagiousness	Not contagious	Highly contagious
Symptoms	Fatigue, body aches, headaches, nausea, low-grade fever, chills	High fever, severe cough, sore throat, runny/stuffy nose, severe fatigue, widespread muscle aches
Timing	Cyclical; appears days before menstruation, resolves once period starts	Random; can occur at any time, lasts 7–14 days
Associated Symptoms	Bloating, cramps, mood swings	Respiratory symptoms (cough, sore throat)

Effective Strategies for Managing Your Symptoms

Dealing with period flu can be challenging, but there are several strategies that can help manage and alleviate the discomfort.

Over-the-Counter Pain Relievers: Nonsteroidal anti-inflammatory drugs (NSAIDs) can be helpful in managing aches, pains, and inflammation associated with period flu. Consult with a healthcare professional or pharmacist to determine the appropriate type and use for your specific needs.
Heat Therapy: Applying a heating pad or taking a warm bath can relax your muscles and help ease body aches and cramps.
Regular, Gentle Exercise: While intense workouts may be too much, gentle exercises like walking, yoga, or swimming can improve circulation and reduce pain. Regular exercise throughout the month can also lessen overall PMS severity.
Balanced Diet and Hydration: Eating small, frequent meals can help stabilize blood sugar and prevent mood swings. Staying well-hydrated is also crucial. Limiting caffeine, salt, and sugar can help reduce bloating and inflammation. Learn more about managing period symptoms with lifestyle changes.
Prioritize Sleep: Get enough rest, especially in the days leading up to your period. Hormonal changes can disrupt sleep, so maintaining good sleep hygiene is important.
Stress Reduction: Stress can worsen PMS symptoms. Practices like meditation, deep breathing exercises, and mindfulness can help manage emotional and physical stress during this time.

When to Seek Medical Advice

While period flu is often manageable at home, certain situations warrant a doctor's visit. If your symptoms are severe, regularly interfere with your daily life, or don't resolve after your period, a healthcare provider can help. They can rule out other conditions with similar symptoms, such as thyroid issues, chronic fatigue syndrome, or premenstrual dysphoric disorder (PMDD), a severe form of PMS. Additionally, if you experience a high fever, a cough, or other respiratory signs, it is wise to see a doctor to rule out an actual viral infection.

Conclusion: Empower Yourself with Knowledge

Experiencing flu-like symptoms before your period is a real and often challenging aspect of the menstrual cycle for many individuals. Understanding that this phenomenon is a result of hormonal shifts, rather than a viral infection, can be empowering. By learning to recognize your body's specific patterns and implementing effective management strategies, you can better navigate this monthly occurrence. Tracking your symptoms, making lifestyle adjustments, and knowing when to seek professional help are all key steps toward finding relief and improving your overall well-being. Knowing what to expect and how to respond can make this recurring experience much more manageable.

Frequently Asked Questions

The flu-like symptoms often experienced before a period include fatigue, muscle and joint aches, headaches, nausea, and sometimes a low-grade fever or chills. These symptoms are part of a phenomenon known as 'period flu,' which is linked to hormonal changes.

No, 'period flu' is not an official medical diagnosis. It is a colloquial term used to describe the flu-like symptoms that some people experience as part of premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD).

Body aches and fatigue before your period are primarily caused by hormonal fluctuations. A drop in progesterone and an increase in inflammatory prostaglandins can lead to muscle pain, headaches, and general malaise. Changes in serotonin levels can also contribute to fatigue and mood shifts.

Period flu is cyclical and typically occurs just before your period, resolving once it starts. The actual flu, a viral infection, can happen at any time and often includes higher fevers, a cough, and a sore throat. Tracking your symptoms relative to your menstrual cycle can help you differentiate.

Some people report experiencing a low-grade fever or chills before their period. This can be caused by the systemic effects of prostaglandins and the resulting inflammation, but it's not the same as the higher fever associated with a viral illness.

Effective management strategies include consulting with a healthcare professional about appropriate pain relief, using heat therapy for aches, getting gentle exercise, prioritizing sleep, and maintaining a balanced, low-sodium diet. Stress reduction techniques can also help.

You should see a doctor if your symptoms are severe enough to disrupt daily life, do not improve once your period starts, or are accompanied by a high fever, severe mood changes, or respiratory symptoms. This is important to rule out other medical conditions or a viral infection.

Yes, natural remedies can be helpful. Increasing hydration, incorporating anti-inflammatory foods, and trying herbal supplements like chasteberry (after consulting a doctor) are some options. Gentle exercise and mindfulness can also help manage discomfort and stress.