Dysmenorrhea (Menstrual Cramps)

What causes period cramps

During a period, the lining of the uterus releases prostaglandins, chemicals that make the uterine muscle contract to shed the lining. High prostaglandin levels cause strong, frequent contractions that briefly reduce blood flow to the uterine muscle, producing cramping pain. Prostaglandins entering the bloodstream also cause nausea, diarrhea, headache and lightheadedness.

Prostaglandin levels are highest in the first 1 to 2 days of bleeding, which is when cramps are worst.

Primary vs secondary dysmenorrhea

Causes of secondary dysmenorrhea

• Endometriosis: tissue similar to the uterine lining grows outside the uterus. Pain often starts in the teens but is frequently dismissed for years. Look for pain with sex, painful bowel movements, and pain not controlled by NSAIDs.
• Adenomyosis: the lining grows into the uterine muscle, causing heavy, painful periods and an enlarged, tender uterus, usually in people over 35.
• Fibroids: benign muscle growths causing heavy bleeding and pressure.
• Pelvic inflammatory disease: infection of the uterus and tubes.
• Copper IUD: can increase cramps and bleeding, especially in the first months.
• Cervical stenosis and congenital uterine abnormalities: rare.
• Ovarian cysts can add pain.

Symptoms

• cramping or aching pain in the lower abdomen, sometimes spreading to the lower back and thighs
• pain that starts a few hours before or with bleeding and peaks in the first 24 to 48 hours
• nausea, vomiting, loose stools
• headache, tiredness and dizziness

Diagnosis

For typical primary dysmenorrhea in teenagers, a history is often enough. A doctor will ask about the timing, severity and pattern of pain, bleeding, sexual activity, contraception and other symptoms. A pelvic exam is not always needed for young people with typical symptoms who respond to treatment.

Further assessment is recommended when secondary dysmenorrhea is suspected:

• pelvic exam and STI tests
• pregnancy test
• pelvic ultrasound, ideally transvaginal, for fibroids, adenomyosis and endometriomas
• MRI in selected cases
• laparoscopy (keyhole surgery) to diagnose and treat endometriosis when imaging is normal but symptoms persist

Treatment

Pain relief

• NSAIDs such as ibuprofen or naproxen are the most effective first treatment, because they block prostaglandin production. Start at the first sign of your period, or 1 to 2 days before if your cycle is predictable, and take regularly for the first 2 to 3 days. Follow the label dose. Avoid NSAIDs if you have kidney disease, stomach ulcers, a bleeding disorder or aspirin-sensitive asthma.
• Acetaminophen (paracetamol) helps less but is an option if you cannot take NSAIDs.

Hormonal treatments

These thin the uterine lining and reduce prostaglandins:

• combined birth control pills, patch or ring, including continuous use to skip periods
• the levonorgestrel IUD
• progestin-only pills, the implant or the injection

Non-drug measures

• Heat: a heating pad or hot water bottle on the lower abdomen works about as well as some pain relievers.
• Exercise: regular aerobic exercise reduces period pain for many people.
• TENS: a small device delivering mild electrical pulses through the skin can help.
• Rest, hydration and sleep.
• Evidence for supplements such as ginger, vitamin B1 and magnesium is limited but suggests possible modest benefit.

Treating secondary causes

Endometriosis, adenomyosis and fibroids may need hormonal therapy, surgery or other specific treatments from a gynecologist.

Outlook

Primary dysmenorrhea often eases with age and after childbirth. Most people achieve good control with NSAIDs and hormonal contraception. Pain that does not respond is a signal to look for a secondary cause; early diagnosis of endometriosis improves quality of life.

Frequently asked questions

What is dysmenorrhea?

Dysmenorrhea is the medical term for painful menstrual periods. Primary dysmenorrhea is common period pain without an underlying disease. Secondary dysmenorrhea is caused by a condition such as endometriosis, adenomyosis or fibroids.

What is the best relief for period cramps?

NSAIDs such as ibuprofen or naproxen, started at the first sign of your period and taken regularly for 2 to 3 days, are the most effective first step. Heat on the lower abdomen and regular exercise also help. Hormonal contraception reduces cramps for many people.

When are period cramps not normal?

See a doctor if cramps stop you from doing usual activities, are not helped by NSAIDs, get worse over time, start after age 25, or come with pain during sex, painful bowel movements, heavy bleeding or fertility problems. These can point to endometriosis or other conditions.

Can period pain be a sign of endometriosis?

Yes. Severe period pain that does not respond to NSAIDs or hormonal contraception, especially with pain during sex, bowel or bladder pain, or pain between periods, can be a sign of endometriosis. Diagnosis often takes years, so raise these symptoms with a doctor.

Why do I get diarrhea and nausea with my period?

Prostaglandins released during periods affect not only the uterus but also the bowel and other organs, causing loose stools, nausea and sometimes vomiting. NSAIDs, which reduce prostaglandins, often help these symptoms too.