Menstrual Cramps (Period Pain)

What period cramps feel like

• cramping, throbbing or a dull constant ache in the lower belly
• pain that may spread to the lower back and inner thighs
• nausea, loose stools, headache, dizziness or tiredness, from prostaglandins acting elsewhere in the body

Pain usually starts a few hours to a day before bleeding, peaks in the first 24 to 48 hours, and fades by day 3.

What causes menstrual cramps

Primary dysmenorrhea

Before a period, the uterine lining makes prostaglandins. These chemicals make the uterine muscle contract to shed the lining. Higher levels mean stronger, more painful contractions that briefly reduce blood flow to the muscle. Primary dysmenorrhea usually starts within 1 to 2 years of the first period, once ovulation is regular, and often improves with age and after childbirth.

Risk factors include starting periods before 12, heavy or long periods, smoking, a family history and stress.

Secondary dysmenorrhea

Period pain caused by an underlying condition is called secondary dysmenorrhea. Clues are pain starting later in life, worsening over time, pain lasting beyond the period, or other symptoms.

How to relieve menstrual cramps

Medicines

• NSAIDs such as ibuprofen or naproxen block prostaglandin production and are the most effective over-the-counter option. Start at the first sign of your period or pain, and take them regularly for the first 2 to 3 days rather than waiting until pain is severe. Follow the label dose. Avoid them if you have stomach ulcers, kidney disease or aspirin-sensitive asthma.
• Acetaminophen (paracetamol) is an alternative if you cannot take NSAIDs, though it is less effective for cramps.
• Hormonal birth control: combined pills, patches, rings, the hormonal IUD, the implant or the injection reduce or stop ovulation and thin the lining, so less prostaglandin is made. Taking pills continuously to skip periods works well for severe cramps.

Non-drug relief

• Heat: a heating pad or hot water bottle on the lower belly works about as well as ibuprofen in some studies.
• Exercise: regular aerobic exercise reduces period pain over time.
• TENS machine: a small device that delivers mild electrical pulses through skin pads can reduce pain.
• Rest and positioning: lying with knees bent or on your side with knees tucked can ease cramps.
• Stop smoking, which worsens period pain.
• Some evidence supports ginger and magnesium. Check with a pharmacist before taking supplements.

When to see a doctor

See a primary care doctor or gynecologist if over-the-counter medicines do not help, if pain makes you miss school or work, or if you have any routine warning signs listed above. A doctor will ask about your periods, sexual history and pain pattern. Tests can include a pregnancy test, STI swabs, a pelvic exam and a pelvic ultrasound. Laparoscopy (keyhole surgery) is the definitive way to diagnose endometriosis, though many people start treatment based on symptoms and imaging first.

Read more about painful periods as a condition at dysmenorrhea.

Cramps but no period

Cramping without bleeding can be:

• premenstrual cramps in the days before a period
• ovulation pain mid-cycle
• early pregnancy, including implantation cramps, or an ectopic pregnancy
• endometriosis, ovarian cysts or fibroids
• bowel causes such as constipation or irritable bowel syndrome

Take a pregnancy test if your period is late.

Frequently asked questions

What is the fastest way to relieve period cramps?

Taking an NSAID such as ibuprofen or naproxen at the first sign of pain, combined with a heating pad on the lower belly, works fastest for most people. Gentle movement, such as walking, can also help. Follow the label dose.

Is it normal to have very painful periods?

Some cramping is normal, but pain that stops you going to school or work, or that does not improve with over-the-counter medicine, is not something you have to live with. It may be severe primary dysmenorrhea or a condition such as endometriosis, and both are treatable.

Why are my period cramps getting worse as I get older?

Primary cramps usually improve with age. Cramps that get worse over the years, especially after 25, suggest secondary dysmenorrhea from endometriosis, adenomyosis or fibroids. See a doctor for an exam and possibly an ultrasound.

Can birth control help menstrual cramps?

Yes. Hormonal methods such as the combined pill, hormonal IUD, implant or injection reduce or stop ovulation and thin the uterine lining, which lowers prostaglandin levels and pain. Many people find cramps improve greatly within 3 months.

Why do I get diarrhea with menstrual cramps?

The prostaglandins that make the uterus contract also act on the bowel, causing loose stools, cramping and sometimes nausea. NSAIDs reduce prostaglandins and can ease both the cramps and the bowel symptoms.