What Is Period Flu?

Medically Reviewed by Jabeen Begum, MD on May 10, 2023
5 min read

Do you feel nauseated, dizzy, or bogged down by headaches as if you have the flu right around the time of your period? You’re not alone. Many people who have periods experience something similar and often call it “period flu.” But it isn’t really the flu (influenza), and you can’t spread it to others.

These flu-like feelings are similar to or overlap with a group of symptoms that doctors call dysmenorrhea (painful periods) or premenstrual syndrome (PMS). Doctors don’t clearly understand what causes these symptoms, but hormonal changes during this time may have a role to play.

Period flu is not an official medical diagnosis, so there is no specific set of symptoms. The symptoms of PMS vary from person to person. The feelings of malaise and pain may kick in just before or at the time you start your period each month. For others, these symptoms may begin after they ovulate. This usually happens around 10-16 days before you start your period, depending on your menstrual cycle.

The pain may range from mild to severe, but it usually goes away with 1-3 days.

Other symptoms may include:

  • Nausea
  • Diarrhea or constipation
  • Dizziness
  • Vomiting
  • Fatigue
  • Headache
  • Cramps
  • Bloating
  • Backache
  • Pain or pressure in your belly

If the symptoms are serious enough, they may affect your quality of life.

Experts believe that changes in the levels of certain chemicals in your body during or before your period have a link to premenstrual symptoms.

Prostaglandins are molecules that act as chemical messengers in the body much like hormones. If you’re feeling feverish, it usually means your body is fighting off a viral, bacterial, or fungal infection. Your immune system activates antibodies and other chemicals like prostaglandin to destroy the virus or bacteria. When this happens, your body temperature goes up.

Your body also produces prostaglandin in the lining of your uterus when you start your period. These molecules bind with receptors in the hypothalamus, the part of the brain that controls your body’s temperature. This causes the low-grade fever.

Prostaglandins also cause strong muscle contractions in the uterus that lead to pain, discomfort, nausea, and diarrhea among some women. If the contractions are too strong, they may press against surrounding blood vessels and cut off some of the oxygen supply. This leads to the cramping that you may feel.

Estrogen levels also dip or change rapidly around this time. This can cause fatigue, cramps, and mood swings.

Ovulation can also increase your core body temperature (basal body temperature) for a couple of days.

We need more research to completely understand all of the causes for these symptoms.

There are a few things you can do to manage the flu-like symptoms.

You can:

Take pain relievers. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, are a class of over-the counter (OTC) drugs that can ease pain during your period. They’re also designed to cut down prostaglandin production. Take them as soon as you start bleeding or whenever you begin to have cramps. If you can’t take NSAIDs, try an OTC acetaminophen product.

Use birth control pills. Hormonal birth control can also help ease pain and thin your uterine lining to lower prostaglandin production. This also reduces muscle contraction. If your symptoms are very bad, you may take NSAIDs and birth control pills together. Before you do, check with your doctor to make sure that’s right for you.

Take antidiarrheal medications. OTC drugs may clear up diarrhea or nausea.

Try heat therapy. Place a heating pad or hot water bottle on your belly, back, or thighs or wherever you feel pain or aches.

Get a massage. This can improve blood flow and give you some relief.

Exercise before and during your period has been known to reduce period symptoms, especially pain and cramps. Don’t smoke, and limit how often you drink beverages with caffeine or alcohol, as these may trigger some of the symptoms. Try to rest when you can.

If you regularly have flu-like symptoms around the time of your period and it’s affecting your quality of life, check in with your OB/GYN, a doctor who specializes in women’s health, or your primary care doctor. They may run some tests to rule out other medical issues that may be causing these symptoms.

If you have other symptoms such as coughing, a runny nose, or a sore throat, get tested for COVID-19 and the seasonal flu. Your doctor will tell you the best treatments for these. They are contagious, and you will need to take steps to limit the spread.

If you use a tampon during your period, you may be at risk for a condition called toxic shock syndrome, especially if you leave them in for long periods of time. This is potentially a life-threatening illness. It’s a bacterial infection that causes flu-like symptoms along with a fever that spikes over 102 F and a rash that looks like a sunburn or red dots on your skin. If you notice this, get help right away or head to the nearest hospital.

You may have a variety of problems during your menstrual cycle. Most are common. They include: 

  • Blood loss and clots. Small blood clots are common. But if you need to change your pad or tampon less than every 2 hours – or have quarter-size or larger clots – let your doctor know.
  • Cramping. Cramps can start before your last period and last throughout the bleeding process. If they are mild, like someone’s giving your ovaries a squeeze, it’s normal. If you are doubled over in pain, check with your doctor.  
  • Moodiness. You can’t avoid mood swings that come with your period, thanks to hormones. As they rise and fall, so does your mood. It may help you to get good sleep, stay active, and steer clear of caffeine and unhealthy foods.
  • Cycle issues. The average menstrual cycle is 28 days, and anything between 21 and 35 is normal. If your cycle changes, it could be due to stress, illness, weight fluctuations, and diet. Your cycle also depends on ovulation, or when your ovaries release an egg about halfway through your cycle.
  • Skipping a period. A missed period doesn’t necessarily mean you’re pregnant. Stress, sickness, or heavy exercise can affect your period sometimes.
  • Nausea. Nausea is a normal part of your period. Prostaglandin can cause vomiting, diarrhea, and headaches.