Menstrual Cramps: What Causes Them and What Actually Helps

Common is not the same as unimportant

Period cramps are so common that many people are taught to just put up with them. The American College of Obstetricians and Gynecologists (ACOG) says more than half of people who menstruate have some pain for one to two days each month. Usually it is mild. For some, it is bad enough to keep them from school, work, or normal life for several days every cycle. Research reflects the same spread: a 2014 review in Epidemiologic Reviews (Ju, Jones, and Mishra) found reported rates of painful periods ranging from 16 to 91 percent across studies, with severe pain in roughly 2 to 29 percent.

The medical word for period pain is dysmenorrhea. Knowing which kind you have, and what actually works against it, can turn a lost day each month into a manageable one. It can also flag pain that deserves a closer look.

What causes the cramping

ACOG explains the ordinary kind, called primary dysmenorrhea, this way. The lining of the uterus makes natural chemicals called prostaglandins. Prostaglandins make the muscles and blood vessels of the uterus contract, which helps shed the lining. On the first day of a period, prostaglandin levels are high. As bleeding continues and the lining sheds, the levels fall. That is why cramps tend to be worst at the start and ease after the first few days.

Higher prostaglandin levels can also explain the other symptoms that sometimes ride along with severe cramps. ACOG lists diarrhea, nausea, vomiting, headache, and dizziness. The pain itself is usually felt low in the belly, and can spread into the lower back and thighs.

Primary dysmenorrhea typically starts soon after periods begin in the teen years. ACOG notes that for many people it becomes less painful with age and may improve after giving birth.

When cramps point to something else

The second kind, secondary dysmenorrhea, is pain caused by a condition in the reproductive organs. ACOG describes a different pattern: the pain tends to get worse over time and often lasts longer than ordinary cramps. It may begin a few days before a period, build as the period continues, and not go away when bleeding stops.

Conditions that can cause it include:

• Endometriosis, where tissue similar to the uterine lining grows outside the uterus and can cause pain, scarring, and adhesions
• Adenomyosis, where that tissue grows into the muscle wall of the uterus, more common in people who are older and have had children
• Fibroids, growths in or on the uterus, some of which cause pain and heavy bleeding
• Other conditions that flare during a period, which ACOG says can include Crohn's disease and urinary disorders

The pattern matters more than any single bad month. Pain that first appears years after your periods started, pain that is steadily getting worse, pain between periods or during sex, and cramps that come with very heavy bleeding all deserve a conversation with a clinician. Our guides to endometriosis and heavy menstrual bleeding go into those conditions in more detail.

What works: NSAIDs, timed well

Because prostaglandins drive the pain, medicines that lower prostaglandins are the first step. These are nonsteroidal anti-inflammatory drugs, or NSAIDs. Ibuprofen and naproxen are the familiar over the counter options.

Timing is the part most people get wrong. ACOG says NSAIDs work best when taken at the first sign of your period or pain, and they are usually needed for only one or two days. Waiting until the cramps are at full strength means chasing prostaglandins that are already doing their work. If your periods are predictable, having the medicine ready at the first twinge makes a real difference.

The evidence supports this. A 2015 Cochrane review (Marjoribanks and colleagues) found NSAIDs appear very effective for period pain compared with a placebo, with no clear evidence that one NSAID works better than another. They do have side effects, mostly stomach upset. ACOG says people with bleeding disorders, asthma, aspirin allergy, liver damage, stomach disorders, or ulcers should not take NSAIDs. Follow the label dose, and ask a pharmacist or clinician if you have any of those conditions or take other medicines.

Hormonal birth control

When NSAIDs are not enough, or when someone also wants contraception, hormonal methods are a common next step. ACOG notes that methods containing estrogen and progestin, including the pill, the patch, and the vaginal ring, can be used to treat painful periods. Progestin only methods, such as the implant and the hormonal IUD, can also reduce period pain. Many of these work by thinning the uterine lining, which means fewer prostaglandins and often lighter bleeding. Some methods can be used continuously to skip periods altogether. Our contraception guide compares the options.

Heat, movement, and other things you can do at home

Heat. A heating pad or adhesive heat patch on the lower belly is low cost and low risk. Small trials have found that continuous low level heat can ease cramps, and some found it comparable to an over the counter pain reliever. It can also be combined with an NSAID.

Exercise. A 2019 Cochrane review (Armour and colleagues) found that regular exercise, such as yoga or aerobic activity done a few times a week, may meaningfully reduce period pain intensity. The authors rated the evidence as low quality, so the effect size is uncertain, but the downside is small and the other health benefits are not.

Sleep and routine. Pain feels worse when you are exhausted. If you know which days are usually hardest, planning a lighter schedule or a later start can help more than toughing it out.

Be careful with supplements. Many products are marketed for period pain. Evidence for most of them is thin or mixed, and supplements are not checked for effectiveness before they are sold. If you want to try one, tell your clinician, especially if you take other medicines.

When to see a clinician

ACOG says if you have painful periods, you and your ob-gyn should talk about your symptoms and your cycle. A visit may include a pelvic exam. If medicine does not relieve the pain, the focus shifts to finding the cause, which may involve an ultrasound and, in some cases, laparoscopy, a minimally invasive surgery that lets the doctor look inside the pelvis.

Make an appointment if:

• NSAIDs taken early and at the right dose do not bring the pain to a level you can function with
• you regularly miss school, work, or plans because of your period
• the pain is getting worse over months or years
• cramps started for the first time well after your periods began
• you have pain during sex, pain between periods, or very heavy bleeding
• you are trying to get pregnant and have significant pelvic pain

Get urgent care for sudden severe pelvic pain, pain with fever, fainting, or pain when there is any chance of pregnancy. Those can signal problems such as an ectopic pregnancy, an ovarian cyst that has twisted or burst, or an infection, and they are not ordinary cramps.

It can help to bring notes to the visit. Write down when pain starts and stops relative to bleeding, how heavy the bleeding is, what you took and when, and what you had to cancel. A pain diary or a cycle tracker turns "my periods are bad" into a pattern a clinician can act on.

The short version

Most period cramps come from prostaglandins, peak on the first day, and respond well to an NSAID taken at the first sign of pain. Hormonal birth control, heat, and regular exercise can add relief. Cramps that keep getting worse, last beyond your period, or arrive with heavy bleeding or pain during sex are a reason to look for a cause, not a reason to keep enduring them.

Sources

• American College of Obstetricians and Gynecologists, Dysmenorrhea: Painful Periods (FAQ): acog.org/womens-health/faqs/dysmenorrhea-painful-periods
• Ju H, Jones M, Mishra G. The prevalence and risk factors of dysmenorrhea. Epidemiologic Reviews. 2014;36:104-113.
• Marjoribanks J, Ayeleke RO, Farquhar C, Proctor M. Nonsteroidal anti-inflammatory drugs for dysmenorrhoea. Cochrane Database of Systematic Reviews. 2015;7:CD001751.
• Armour M, Ee CC, Naidoo D, et al. Exercise for dysmenorrhoea. Cochrane Database of Systematic Reviews. 2019;9:CD004142.
• MedlinePlus, Period Pain: medlineplus.gov/periodpain.html

Educational only. Severe or worsening pelvic pain needs an exam, and your own clinician's advice comes first.