Period Flu: What Causes Flu-Like Symptoms During PMS

• Researched and written by: Dr Akshara CH, MBBS
  
• Edited by: Vaibhavi Kodnani
• Medical inputs by: Dr Poonguzhali Liston, MBBS, MS OBG, FMAS, DRM, FRM, CIMP
  
• Medically reviewed by: Dr Yash Bahuguna, MBBS, MS, DNB, ISGE Certified Practitioner for PCOS
  

TL;DR

• Period flu is a non-medical term used to describe flu-like symptoms that appear before your period as part of premenstrual syndrome (PMS).[1,2,3,4]
  

• Symptoms of period flu include feeling achy, tired, or slightly unwell in the week or two before bleeding starts. They usually improve once the period begins.[1,2]
  

• Hormonal shifts in the luteal phase (second half of your cycle), especially changes in estrogen and progesterone, are the main cause of period flu. High prostaglandin levels also cause these symptoms.[1,12]
  

• Relief strategies such as anti-inflammatory medicines, regular exercise, and lifestyle measures can help.[2,4,12]
  

• If symptoms are severe, persistent, or affect quality of life, it is advisable to talk to a healthcare provider to rule out PMDD or other conditions.[2,12]

What Is Period Flu?

“Period flu” is a non-medical term many women use to describe experiencing flu-like symptoms just before their period. Unusual tiredness, body aches, headaches, or feeling unwell in general are common complaints.

Period flu symptoms are commonly associated with premenstrual syndrome (PMS). They are noticeable during the late luteal or premenstrual phase, a few days before the period. Emotional symptoms of PMS, such as mood swings, may also be present.

However, some women may also notice period flu symptoms after ovulation, in the luteal phase of the menstrual cycle, around two weeks before their period. For most, the symptoms settle once menstrual bleeding begins.[1,2]

Even though period flu can seem similar to a mild viral illness, it is not caused by an infection and is not contagious. It is rather a result of normal hormonal shifts in the body.

What Are Period Flu Symptoms?

Period flu symptoms can make you feel as though you are coming down with something, even though you are not actually sick.[1,2]

You may notice physical signs and symptoms:

• Headache
  

• Fatigue or low energy
  

• Muscle aches or joint pain
  

• Bloating
  

• Breast tenderness
  

• Sleep disturbance
  

• Heavy or run down feeling
  
  

Some women experience nausea, loose stools, or stomach discomfort around the time their period starts.

Quick insight: A high fever, ongoing cough, or severe respiratory symptoms are not typical of period flu. If you notice these, it is important to consider another cause and speak to a doctor if needed.

What Causes Period Flu?

Period flu symptoms are linked to hormonal changes that happen during the second half of your menstrual cycle, including the luteal and premenstrual phases. 

Hormonal fluctuations

During the luteal phase, progesterone rises and estrogen levels fluctuate. If pregnancy does not occur, both these hormones decline in the late luteal or premenstrual phase. 

Research shows that women with PMS generally have normal hormone levels, but they are more sensitive to these cyclical hormonal changes.[1,2] These fluctuations influence neurotransmitters or brain chemicals such as serotonin, which affect mood, pain perception, sleep, and overall wellbeing. This sensitivity helps explain why you may feel tired, achy, or generally unwell before your period.

Prostaglandins and inflammation

As your period approaches, the production of prostaglandins increases. These are hormone-like chemicals that help the uterus contract and shed its lining. Elevated prostaglandins increase pain and inflammation in the body, causing cramps, headache, and whole-body discomfort. It also affects the nearby regions, such as the digestive organs of the gastrointestinal tract, leading to symptoms like nausea and diarrhea.[3] These effects can collectively contribute to a flu-like feeling. 

There is some evidence that inflammation levels may be higher in women with PMS compared to those without it.[5] However, inflammation is considered a contributing factor, not the main cause.

Nervous system sensitivity

Hormonal changes influence central nervous system activity, including the brain and the spinal cord. This affects how the body perceives and responds to pain.[1] The increased pain sensitivity can make normal physical sensations, like cramps or body aches, feel more intense in the premenstrual phase.

Premenstrual Syndrome and Premenstrual Dysphoric Disorder 

Both PMS and premenstrual dysphoric disorder (PMDD) follow the same monthly timing. The main difference is the severity of symptoms and their impact on daily life.

With PMS, you may notice physical symptoms such as fatigue, headache, bloating, breast tenderness, and body aches. You may also feel slightly irritable, low, or more emotional than usual. The symptoms can be uncomfortable and frustrating, but most women are still able to go to work, manage responsibilities, and carry on with their everyday routines.[1,2]

PMDD is a more severe form of PMS.[2] Emotional symptoms are more intense and feel harder to manage. You may experience:

• Severe mood swings
  

• Irritability or anger
  

• Persistent low mood
  

• Intense anxiety or tension

Physical symptoms may still occur, but for a PMDD diagnosis, mood changes that are severe enough to disrupt work, relationships, or daily functioning must be present.[2]

In simple terms, PMS can make you feel unwell, while PMDD can make it challenging to function normally. If your symptoms feel overwhelming, cause significant distress, or affect your quality of life, it is important to speak to a doctor for evaluation and support.[2]

How Do You Know If You Have Period Flu or Normal Flu?

It can be confusing to differentiate between period flu and normal flu. But there are a few clear differences that can help you tell them apart.[1,2]

 

Why tracking matters: Tracking symptoms for at least three menstrual cycles is needed to confirm a PMS diagnosis.[1,2] Note your symptoms, when they begin, how long they last, and whether they improve when your period starts. A clear monthly pattern strongly supports period flu as part of PMS rather than a viral flu infection.

Berry’s Tips: How to Relieve Period Flu Symptoms

Management for period flu focuses on reducing body aches, supporting energy levels, and preventing symptoms from escalating each month.[1,2,3,4]

Prioritise sleep

When sleep is disrupted, period flu symptoms can feel much worse. You may have less energy or feel fatigued throughout the day.[1]

Try these simple habits in the days before your period:

• Go to bed and wake up at the same time each day.
  

• Avoid caffeine late in the day, at least four hours before you sleep.
  

• Limit screen time at night. Shut down all electronic devices at least an hour before bedtime.
  

• Follow a calming wind-down routine before bed, such as performing relaxing yoga poses or listening to soothing music.
  

Better sleep will not eliminate hormonal shifts, but it can reduce how drained you feel.

Keep moving 

It may feel counterintuitive, but regular aerobic or cardiovascular exercise is associated with reduced PMS severity.[2,4] 

Exercising releases endorphins, your body’s natural painkillers, thus reducing inflammation and perception of pain. It also improves blood circulation and oxygen flow in the body. That’s why staying physically active can reduce the frequency and severity of body aches, fatigue, and other flu-like symptoms before periods. 

You can try a variety of activities that suit you and make you happy:

• Take a 30-minute brisk walk outdoors or on a treadmill.
  

• Go for a light cycling session for 20–30 minutes.
  

• Do 20–30 minutes of swimming.
  

• Practice 15–20 minutes of gentle yoga or stretching.
  

• Follow a short, low-impact aerobic workout video at home.
  

Remember: The type and intensity of exercise should depend on your overall health and any existing medical conditions. If you have underlying health issues or are new to exercise, it is best to start slowly and seek guidance from a healthcare provider or qualified fitness professional.

Limit foods that cause bloating

If you experience bloating or a heavy, puffy feeling as a part of period flu, a few changes in your diet may help with the symptoms. Reducing salt intake in the week before your period may reduce fluid retention. Cutting back on high sodium foods such as packaged snacks, processed meals, and pickled items is a good place to start. 

Eating regular, balanced meals comprising complex carbs, protein, healthy fats, fresh vegetables, and yoghurt can also help keep your energy levels steady, helping you effectively manage PMS fatigue.[2,12]

Manage stress levels

Chronic stress increases hormones such as cortisol in the body. High cortisol levels are linked to greater inflammation and heightened pain sensitivity, which can make premenstrual symptoms feel more intense. That’s why body aches and fatigue may feel especially overwhelming when stress levels are high.[2,4,12]

Practicing relaxation techniques for a few minutes daily can help manage stress, reduce PMS severity, and promote overall well-being. You can consider the following strategies:

• Practice box breathing for 5 minutes. Inhale for 4 seconds, hold for 4 seconds,      exhale for 4 seconds, and hold again for 4 seconds. A breathing device can help guide your practice.
  

• Do 10 minutes of guided meditation using a relaxation or mindfulness app or video.
  

• Spend 5 to 10 minutes doing gentle stretching to release tension in your neck, shoulders, and back.
  

• Set aside 10 to 15 minutes each evening for a quiet wind-down routine such as reading, journaling, or listening to calming music.

When Should You See a Doctor?

Mild PMS symptoms that resolve on their own are not concerning. If your period flu symptoms become severe, persistent, or affect quality of life, it may indicate an underlying cause.

It is a good idea to speak to a doctor if you notice any of the following:

• Your symptoms affect your daily activities. Fatigue, body aches, or mood changes become severe enough to interfere with work, studies, relationships, or routine activities.
  

• Your mood changes feel intense or do not improve. You experience severe irritability, anxiety, sadness, crying spells, or emotional distress that feel difficult to manage.
  

• You develop high fever or signs of an infection. Fever, chills, persistent cough, or other symptoms of an infection that are generally not a part of period flu.
  

• Your symptoms do not settle after your period begins. Premenstrual symptoms usually improve once menstrual bleeding starts. If they continue throughout the month or occur at random times during the month, it may have another cause.

Diagnosis and treatment

Your doctor will discuss your symptoms and cycle patterns to evaluate whether your symptoms are related to PMS, PMDD, or another underlying condition such as anemia or thyroid disease. 

A healthcare professional will tailor your treatment plan based on your medical diagnosis.[1,2,12]

For physical PMS or PMDD symptoms, they may recommend anti-inflammatory medications or supplements. 

Nonsteroidal anti-inflammatory drugs (NSAIDs): Some women find relief from period flu symptoms by using nonsteroidal anti inflammatory drugs (NSAIDs). These medicines help reduce inflammation and block the production of prostaglandins, natural chemicals that rise around menstruation and contribute to pain, headaches, body aches, nausea, and other physical symptoms.[3,12]

Disclaimer: Anti-inflammatory medicines may not be suitable for people with stomach ulcers, kidney problems, bleeding disorders, or certain heart conditions. They should only be used when needed in the recommended dose after consulting a doctor.

Research has shown some supplements can help with PMS symptom relief. It includes:

• Calcium[6]
  

• Vitamin B6[7]
  

• Magnesium[8]
  

• Omega-3 fatty acids[9]
  

• Vitamin D[10,13]
  

• Zinc[11]
  
  

Your doctor may discuss relevant options based on your symptoms. 

Disclaimer: These supplements do not work instantly. You may need to take them regularly for a few menstrual cycles before noticing improvement in your symptoms. It is also important to speak to a doctor before starting any new supplement, especially if you have existing health conditions or take other medications.

The Bottom Line

Period flu refers to recurring, flu-like symptoms that may appear in the luteal or premenstrual phase and improve once bleeding begins. Most common symptoms include fatigue, body pain, headaches, and gastrointestinal symptoms like bloating, nausea, and diarrhea. 

Period flu isn't an infection. Increased sensitivity to normal hormonal changes and high levels of prostaglandins in the body are primary causes. Tracking your cycle and starting supportive measures early can make each month more manageable. Proper rest, regular cardiovascular exercise, a daily relaxation routine, and targeted diet changes in the luteal phase can reduce the severity and recurrence of flu-like symptoms before periods. 

However, if your symptoms are severe or disruptive, your doctor can recommend helpful medications or supplements. 

FAQs on Period Flu

Can you have flu-like symptoms before your period?

Yes, flu-like symptoms such as fatigue, body aches, headaches, and stomach discomfort are recognised physical features of PMS. However, fever, cold, cough, and other respiratory symptoms seen in viral infections are not typical of period flu.

How soon does period flu start?

Period flu usually begins in the premenstrual phase, in the days leading up to your period. However, some women may notice changes earlier during the luteal phase, around 2 weeks before their period begins. 

How long can PMS flu last?

Flu-like symptoms typically last a few days and resolve shortly after menstrual bleeding begins.

Why do I feel generally unwell before my period?

Sensitivity to normal hormonal fluctuations and high prostaglandin levels contribute to physical PMS symptoms like fatigue, body aches, headaches, and stomach discomfort. As a result, you may feel generally unwell, similar to coming down with the flu. 

Does your immune system weaken before your period?

Hormonal fluctuations influence immune and inflammatory pathways across the menstrual cycle. However, PMS is primarily understood as a response to hormonal sensitivity rather than immune suppression.

Image credits: Illustrations created by Leisha Chavan using AI tools for educational purposes.

References

1. Gudipally PR, Sharma GK. Premenstrual syndrome.
   
2. American College of Obstetricians and Gynecologists. Premenstrual syndrome (PMS). Accessed February 6, 2026.
   
3. Barcikowska Z, Rajkowska-Labon E, Grzybowska ME, Hansdorfer-Korzon R, Zorena K. Inflammatory markers in dysmenorrhea and therapeutic options. International journal of environmental research and public health. 2020 Feb;17(4):1191.
   
4. Royal College of Obstetricians and Gynaecologists. Managing premenstrual syndrome (PMS). Accessed February 6, 2026.
   
5. Sultana A, Heyat MB, Rahman K, Kunnavil R, Fazmiya MJ, Akhtar F, Sumbul, Vidal Mazón JL, Rodriguez CL, De La Torre Diez I. A systematic review and meta-analysis of premenstrual syndrome with special emphasis on herbal medicine and nutritional supplements. Pharmaceuticals. 2022 Nov 8;15(11):1371.
   
6. Thys-Jacobs S, Starkey P, Bernstein D, Tian J, Premenstrual Syndrome Study Group. Calcium carbonate and the premenstrual syndrome: effects on premenstrual and menstrual symptoms. American journal of obstetrics and gynecology. 1998 Aug 1;179(2):444-52.
   
7. Wyatt KM, Dimmock PW, Jones PW, O'Brien PS. Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review. Bmj. 1999 May 22;318(7195):1375-81.
   
8. Fathizadeh N, Ebrahimi E, Valiani M, Tavakoli N, Yar MH. Evaluating the effect of magnesium and magnesium plus vitamin B6 supplement on the severity of premenstrual syndrome. Iranian journal of nursing and midwifery research. 2010 Dec;15(Suppl1):401.
   
9. Kashanian M, Sohrabi N, Ghafoori SS. P-1004-Evaluation of the effect of Omega-3 fatty acids in the treatment of premenstrual syndrome. European Psychiatry. 2012 Jan 1;27:1.
   
10. Bertone-Johnson ER, Hankinson SE, Bendich A, Johnson SR, Willett WC, Manson JE. Calcium and vitamin D intake and risk of incident premenstrual syndrome. Archives of internal medicine. 2005 Jun 13;165(11):1246-52.
    
11. Shivyari FT, Mighani S, Baghdadi G, Ranjbaran M, Javadi M. Effects of Zinc Supplementation on Premenstrual Syndrome: A Systematic Review of Observational and Randomized Clinical Trials. Nutrition & Food in Health & Disease. 2025 Oct 1;12(4).
    
12. American Academy of Family Physicians. Premenstrual syndrome. Accessed February 6, 2026.
    
13. Tartagni M, Cicinelli MV, Tartagni MV, Alrasheed H, Matteo M, Baldini D, De Salvia M, Loverro G, Montagnani M. Vitamin D supplementation for premenstrual syndrome-related mood disorders in adolescents with severe hypovitaminosis D. Journal of pediatric and adolescent gynecology. 2016 Aug 1;29(4):357-61.