What Is the Period Flu?

Do you start feeling sick before you get your period? You may be experiencing what’s known as the period flu. It refers to a combination of physical, psychological, and emotional symptoms that are typically grouped under premenstrual syndrome (PMS).

These symptoms can begin anywhere from a week or two before the first day of your period or during your period. Their severity ranges from mild to moderate to severe.

Young woman feeling sick on the sofa at home

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Is the Period Flu Real?

“Period flu” is not a medical term, but it describes various flu-like symptoms that some people experience before their period. The fluctuating symptoms and their impact on your life are not in your head.

A diary documenting your menstrual cycles and the symptoms you experience throughout the month can help you and your healthcare provider determine whether you have the period flu. In some cases, your practitioner may want to rule out other medical conditions that can cause similar symptoms during your menstrual cycle, such as premenstrual dysphoric disorder and irritable bowel syndrome

Period Flu Symptoms

Period flu symptoms vary. They can be hardly noticeable, mildly inconvenient, or potentially impairing. 

Common symptoms may include:

  • Abdominal cramps and pain
  • Bloating
  • Back pain
  • Breast fullness, tenderness, and pain
  • Digestive problems including constipation and diarrhea 
  • Headaches
  • Muscle or joint pain
  • Problems concentrating
  • Skin breakouts (acne)
  • Sleep disturbances
  • Water retention
  • Vomiting 
  • Fatigue


If your symptoms are consistently severe and have a disabling effect on your mental health, you may be dealing with premenstrual dysphoric disorder (PMDD). While less common than PMS, PMDD is a serious problem for 3% to 8% of all girls and women who experience PMS.


The exact cause of period flu is unclear. These flu-like symptoms are hypothesized to be the result of hormonal fluctuations that take place during the menstrual cycle. 

Research suggests that the flu-like symptoms may be caused by a person’s reaction to when progesterone is broken down and levels drop during the latter half of their menstrual cycle.

Progesterone may also play a role as a neurotransmitter, a chemical messenger in the brain. For example, a drop in progesterone levels may affect your brain’s ability to modulate other chemicals related to how you feel, like serotonin (a happy hormone).

Hormonal Change Theory Explained

In the latter stage of your menstrual cycle, known as the luteal phase, your body releases an egg from an ovary. This is known as ovulation. If your egg isn’t fertilized, the sex hormones estrogen and progesterone drop sharply as your egg begins disintegrating and your uterine lining begins shedding. This hormonal drop is what’s typically associated with the flu-like symptoms.

Other theories on the potential causes of PMS include:

  • Allergy to progesterone
  • Carbohydrate metabolism changes
  • Estrogen-progesterone imbalance
  • Excessive aldosterone, or ADH (the hormone that helps regulate the metabolism of sodium, chloride, and potassium)
  • Hyperprolactinemia (an excessive secretion of prolactin, the hormone that stimulates breast development)
  • Retention of sodium and water by the kidneys
  • Low blood sugar
  • Psychogenic factors


Treatment options for PMS, which may include symptoms described as period flu, include:

  • Hormonal contraceptives: These may be prescribed to help improve hormone-related symptoms of PMS or PMDD.
  • Antidepressants: Selective serotonin reuptake inhibitors (SSRIs) may help with psychological symptoms. Most of the time they are prescribed daily, but sometimes are limited to just two weeks before your period begins.
  • Painkillers: Over-the-counter medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to reduce pain and aches.
  • Diuretics: Water pills may be taken to help reduce bloating (water retention).
  • Supplements: Calcium has been recommended, but other supplements, including vitamin D, herbal remedies like St. John’s Wort, and acupuncture, do not have enough evidence to support their recommendation.

Cognitive Behavioral Therapy for PMS/PMDD

Research suggests that cognitive behavioral therapy may help with PMS or PMDD. One 2019 study showed that the benefits of Internet-based cognitive behavioral therapy can help reduce the symptoms of PMDD. 

Lifestyle Choices

It is well accepted that certain lifestyle choices can help reduce the emotional and physical impact of PMS. Generally speaking, any lifestyle choice that helps you stay healthy and avoid bloating, an upset stomach, mood changes, and sleep disturbance is helpful.

Specific lifestyle suggestions for coping with the period flu include:

  • Avoiding or reducing alcohol, caffeine, salt, and sugar intake
  • Eating a balanced diet, including plenty of whole grains, vegetables, and fruits
  • Exercising at least three to five times a week
  • Getting adequate and good sleep and rest

A Word From Verywell

While the topic of periods has become more mainstream over the years, many of us still struggle with internalized stigma surrounding menstruation. Fear of stigma, judgment, and not being taken seriously can make it difficult to talk to others about how you’re feeling during this time, but help is available.

If you’ve noticed flu-like symptoms that are not improving with lifestyle changes, it may be time to talk to your healthcare provider or a mental health professional about strategies to reduce the impact of PMS or PMDD on your everyday life.

Frequently Asked Questions

  • Are painful periods a sign of something serious?

    Not usually. As many as 90% of women experience some pain or discomfort with their periods. Often, that discomfort can become intense, but this is commonly a result of normal menstrual cramps and is known as primary dysmenorrhea. Secondary dysmenorrhea, however, could be caused by an infection, ovarian cysts, endometriosis, or other gynecological health problems. Talk to your healthcare provider about pain that's new or different.

  • Is it normal to get diarrhea with your period?

    Yes. About 33% of women experience changes in their bowels during menstruation. In most cases, this results in diarrhea, but constipation can also be a problem. Continue to follow a healthy diet and avoid cravings for foods that could irritate your bowels.

  • When I feel sick before my period, is it all in my head?

    You're probably not imagining it. However, your mood or mental state may affect how you feel physically around your period. Mood disorders such as depression are common just before menstruation, and there's a link between emotional symptoms and gastrointestinal problems such as bowel disorders. 

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Boston Children’s Hospital. Premenstrual syndrome (PMS) symptoms and causes.

  2. Institute for Quality and Efficiency in Health Care. Premenstrual syndrome: overview.

  3. Hofmeister S, Bodden S. Premenstrual syndrome and premenstrual dysphoric disorder. Am Fam Physician. 2016;94(3):236-240. PMID:27479626.

  4. Weise C, Kaiser G, Janda C, et al. Internet-based cognitive-behavioural intervention for women with premenstrual dysphoric disorder: a randomized controlled trialPsychother Psychosom. 2019;88(1):16-29. doi:10.1159/000496237.x

  5. American Academy of Family Physicians. Dysmenorrhea.

  6. Bernstein MT, Graff LA, Avery L, Palatnick C, Parnerowski K, Targownik LE. Gastrointestinal symptoms before and during menses in healthy women. BMC Women’s Health. 2014;14(1):14. doi:10.1186%2F1472-6874-14-14

By Michelle Pugle
Michelle Pugle, BA, MA, is an expert health writer with nearly a decade of contributing accurate and accessible health news and information to authority websites and print magazines. Her work focuses on lifestyle management, chronic illness, and mental health. Michelle is the author of Ana, Mia & Me: A Memoir From an Anorexic Teen Mind.