Medicine does not know why menstruation is uncomfortable, or why it is much more uncomfortable for some women than for others, or from month to month.

Occasionally, severe menstrual pain indicates the presence of endometriosis (a condition in which uterine tissue is growing in places other than the uterus) or uterine fibroids (benign tumors in the uterus). In most cases, no identifiable abnormality can be found. Natural substances known as prostaglandins seem to play a central role in menstrual pain, but their detailed actions are not fully understood. Anti-inflammatory drugs such as ibuprofen and naproxen relieve pain and reduce levels of some prostaglandins. These drugs are the mainstay of conventional treatment for menstrual pain. Oral contraceptive treatment may also help.

There is some evidence that the supplements fish oil, magnesium, and vitamin E may help reduce menstrual pain.

Fish Oil

The omega-3 fatty acids in fish oil are thought to have anti-inflammatory effects. Omega-3 may relieve dysmenorrhea by affecting the metabolism of prostaglandins and other factors involved in pain and inflammation.1

In a 4-month study of 42 young women ages 15 to 18, half the participants received a daily dose of 6 g of fish oil, providing 1,080 mg of EPA (eicosapentaenoic acid) and 720 mg of DHA (docosahexaenoic acid) daily.2 After 2 months, they were switched to placebo for another 2 months. The other group received the same treatments in reverse order. The results showed that these young women experienced significantly less menstrual pain while they were taking fish oil.

Another double-blind study followed 78 women, who received either fish oil, seal oil, fish oil with vitamin B12(7.5 mcg daily), or placebo for three full menstrual periods.3 Significant improvements were seen in all treatment groups, but the fish oil plus B 12 proved most effective, and its benefits continued for the longest time after treatment was stopped (3 months). The researchers offered no explanation why B 12 should be helpful.

Krill oil, another source of omega-3 fatty acids, might be helpful as well.17

For more information, including dosage and safety issues, see the full Fish Oil article.

Vitamin E

In a double-blind, placebo-controlled trial, 100 young women complaining of significant menstrual pain were given either 500 IU vitamin E or placebo for 5 days.12 Treatment began 2 days before and continued for 3 days after the expected onset of menstruation. While both groups showed significant improvement in pain over the 2 months of the study (due to the power of placebo), pain reduction was greater in the treatment group than the placebo group.

In another study performed in Iran, 278 adolescents with dysmenorrhea were given either placebo or 200 IU of vitamin E twice daily on the same schedule as above.18 Again, vitamin E proved more effective than placebo.

It is not clear how vitamin E could affect menstrual pain.

For more information, including dosage and safety issues, see the full Vitamin E article.

Magnesium

Preliminary studies suggest that magnesium supplementation may be helpful for dysmenorrhea. A 6-month, double-blind, placebo-controlled study of 50 women with menstrual pain found that treatment with magnesium significantly improved symptoms.9 The researchers reported evidence of reduced levels of prostaglandin F 2 alpha, one of the prostaglandins involved in menstrual pain.

Similarly positive results were seen in a double-blind, placebo-controlled study of 21 women.10

For more information, including dosage and safety issues, see the full Magnesium article.

Acupuncture

A double-blind study of 43 women found some evidence that acupuncturecan be effective for control of menstrual pain.14In addition, a controlled study of 61 women evaluated the effects of a special garment designed to stimulate acupuncture points related to menstrual pain.15Unfortunately, researchers chose to compare treatment to no treatment, rather than to placebo treatment. For this reason, the results (which were positive) mean little. In a review of 30 controlled trials, researchers were unable to draw conclusions about the effectiveness of acupuncture and similar treatments for menstrual pain due to widespread study design problems.24

A smaller, but more recent systematic review from 2011 included 6 acupuncture trials involving 673 women and 4 acupressure trials involving 271 women.25 Acupuncture was associated with pain relief when compared to a placebo (sham) control, anti-inflammatory medication (NSAIDs) and Chinese herbs. Similarly, acupressure was associated with symptom improvement when compared to a placebo control. As in previous reviews, however, researchers found enough weaknesses in the trials to recommend the need for more high-quality studies.

A randomized trial of 66 women with primary dysmenorrhea showed improvement in pain scores with 16 twice-weekly acupuncture-like transcutaneous electrical nerve stimulation (AL-TENS) compared to sham AL-TENS.27