CHAPTER 4 Menstrual Cramps
Dysmenorrhea, commonly referred to as menstrual cramps, affects more than 50% of menstruating women. Women between the ages of 20 and 24 years typically experience the most severe pain. Dysmenorrhea is generally divided into two subcategories. When the menstrual cramps are associated with an identifiable pathology, such as endometriosis (see Chapter 5), it is referred to as secondary dysmenorrhea. When no organic pathologic condition exists, it is classified as primary dysmenorrhea.1 The pain of primary dysmenorrhea usually begins with the onset of menstrual flow and lasts 8 to 72 hours, whereas cramping often occurs before, as well as during menstruation with secondary dysmenorrhea.
Menstrual cramps are believed to be the result of excessive prostaglandin production in the secretory endometrium, which leads to painful uterine contractions. Other symptoms—such as headache, nausea, diarrhea, and back pain—can also be explained by the entry of prostaglandins into the systemic circulation.2 Prostaglandin release is greatest during the first 48 hours of menstruation, which is the period during which most women state their symptoms are worst. Prostaglandin F2α (PGF2α) appears to be the primary cause. PGF2α stimulates the nonpregnant uterus, whereas prostaglandins of the E series induce uterine relaxation. Overproduction of vasopressin, a hormone that stimulates muscle contraction, may be another cause.3 Pain is also partly mediated by ischemia, which is induced by the contraction of the myometrium itself.
TREATMENT
Nonsteroidal Antiinflammatory Drugs
Nonsteroidal antiinflammatory drugs (NSAIDs) are often used to suppress the production of prostaglandins from the arachidonic acid chemical precursor by the enzyme prostaglandin synthetase. Of more than 50 clinical trials conducted on prostaglandin synthetase inhibitors, the fenamates have been shown to be the most effective in relieving menstrual pain.4 These agents not only inhibit prostaglandin production but also compete for prostaglandin-binding sites. Treatment should begin at the first sign of menstrual cramping. Most women only need to use these medications for 2 or 3 days. Side effects may include gastrointestinal upset, blurred vision, headache, and dizziness. Contraindications to the use of NSAIDs include gastrointestinal bleeding, peptic-ulcer disease, and sensitivity to aspirin.
Oral Contraceptives
Oral contraceptives are effective in the treatment of dysmenorrhea. They create an atrophic decidualized endometrium that produces fewer prostaglandins. However, oral contraceptives are not a viable treatment in women who smoke, those with clotting disorders or liver disease, or those who wish to become pregnant.
Omega-3 Fatty Acids
Preliminary data suggest that women with low dietary intake of omega-3 fatty acids (essential fatty acids) experience greater menstrual pain.5 In a small randomized, placebo-controlled crossover study, 42 adolescent girls with primary dysmenorrhea were administered fish oil (1080 mg eicosapentaenoic acid [EPA] and 720 mg docosahexaenoic [DHA] per day) and 1.5 mg of vitamin E per day for 2 months, followed by placebo; or placebo for 2 months followed by the fish oil and vitamin E for 2 months. On a 7-point scale with a score of 4 indicating moderate effectiveness, 73% of the girls rated the treatment a 4 or better.6 The authors of a double-blind, randomized, controlled trial found that a low-temperature extract of the Antarctic krill (Euphausia superba) effectively reduced the amount of analgesics required by women with dysmenorrhea after 45 and 90 days of treatment compared with baseline and compared with women receiving omega-3 fish oil.7
Eskimos consume more fat than just about any other people on the planet and yet they have a much lower incidence of heart disease. The secret may lie in the amount of fish consumed in their diet. Omega-3 fatty acids are polyunsaturated fatty acids found in all seafood, including shellfish, oysters, and shrimp, although the richest sources are salmon, tuna, mackerel, herring, sea bass, and trout. The American Heart Association now recommends eating fish two times a week to prevent heart disease. Other research suggests that fish may also reduce the risk of stroke and improve mood. Although fish are healthy, low in fat, and protein rich, swordfish, shark, tilefish, king mackerel, and tuna steak can contain high levels of mercury. Women should limit consumption of these fish and avoid them altogether during pregnancy and early childhood.
Although the research is preliminary, given the relative safety of fish and fish oil, women with dysmenorrhea may want to eat oily, cold-water fish two or three times per week or consider taking fish-oil supplements. Concerns have been raised with regard to the presence of heavy metals in some sources of fish oil. However, an evaluation of 20 varieties of commercially available fish oil capsules by Consumer Labs showed that none of them contained any detectable level of mercury (<1.5 parts per billion [ppb]).8 By comparison, mercury levels in fish generally range from 10 to 1000 ppb, depending on the fish. Researchers note several possible explanations for the lack of mercury in these supplements, including the use of species of fish that are less likely to accumulate mercury, the fact that most mercury is found in fish meat and not fish oil, and distillation processes that remove contaminants. Flax and pumpkin seeds also contain omega-3 fatty acids and may be used instead of, or in addition to, fish.
Thiamine (Vitamin B1)
A randomized, double blind, placebo-controlled study was conducted in 556 girls ages 12 to 21 years experiencing moderate to very severe primary spasmodic dysmenorrhea. Thiamine hydrochloride (vitamin B1) at a dose of 100 mg/day was found to completely alleviate pain in 87% of participants; 8% experienced some pain relief, and 5% showed no effect.9 This study was conducted in India, where thiamine deficiency is more common than it is in the United States or Europe. At this time, no other trials are available for evaluation. In addition to supplementation, thiamine is present in many foods; it is most abundant in pork, dried fortified cereals, oatmeal, and sunflower seeds.
Vitamin E
In a double-blind clinical study of 100 girls ages 16 to 18 years with primary dysmenorrhea, the participants were randomly assigned to receive 500 IU/day vitamin E or placebo for 2 months. The treatment began 2 days before the onset of menstruation and continued through the first 3 days of bleeding. The severity of pain in the two groups was reduced after treatment, but the reduction was modestly superior in the group treated with vitamin E.10 At the start of the study, the median pain scores on a scale of 0 to 10 were similar: 5.5 in the vitamin E group and 5.4 in the control group. Two months later the girls in the vitamin E group reported an average pain score of 3.5, whereas those receiving placebo reported a pain score of 4.3.
Magnesium
Three small trials have evaluated the efficacy of magnesium for the relief of dysmenorrhea. Overall, magnesium was more effective than placebo for pain relief, and the need for additional medication was less. The investigators noted no significant difference in the number of adverse effects experienced.11 A reduction in inflammatory prostaglandins may be responsible. One study included data on levels of prostaglandin F2α. Women taking magnesium therapy had substantially lower levels of prostaglandin F2α in their menstrual blood than those on the placebo (P < 0.05); these lower levels correlated with a decrease in pain by the participants. Dosage recommendations vary, but the range is generally 300 to 600 mg/day for 3 to 5 days, starting the day before the onset of menses.
Botanical Remedies
Pelvic pain and menstrual cramps are discussed in many classic herbal texts. Various herbal treatments are primarily directed at easing pain and trying to restore a “balanced” constitution. In traditional Chinese medicine, the problem is seen as one of blood stagnation, and herbs and acupuncture are used to correct the underlying imbalance. A practitioner of ayurveda would attempt to restore balance by making recommendations regarding all aspects of life, including diet, exercise, and botanicals, to ultimately help rebalance the constitution. Western-trained herbalists have traditionally relied on botanicals with antispasmodic and anti-inflammatory activity. Bitter herbs that enhance digestion and act on the liver are also included in some formulations.
Much of what has been done over the history of herbalism to relieve pelvic pain and menstrual cramps continues to be relied on by contemporary herbalists. Most practitioners of these systems of medicine still take a “holistic” approach to treatment. The following text presents some of the dietary measures and botanicals that are currently being recommended for menstrual cramps or show some promise of efficacy. Readers should be aware that very few randomized studies have been conducted to support the use of these approaches, although many are well founded in a biologically plausible approach.
Black haw (Viburnum prunifolium).
Black haw was valued in early American medicine for its effectiveness in easing uterine cramping, be it spasmodic dysmenorrhea or threatened miscarriage. King’s American Dispensatory states that black haw “acts promptly in spasmodic dysmenorrhea, especially with excessive flow.”12 The herb was highly valued for its ability to prevent miscarriage. A dark part of U.S. history is reflected in another passage: “It was for a long time customary for planters to compel their female slaves to drink an infusion of black haw daily whilst pregnant to prevent abortion.”12 Black haw was officially entered into the United States Pharmacopoeia in 1882 and remained in the National Formulary until 1960.
An article published in 1939 described the uterine-relaxant effects of a preparation of V. prunifolium in a woman whose uterus was subsequently removed for therapeutic reasons. Strips of uterine tissue were tested with the same extract. Uterine relaxation was found to occur in a dose-dependent manner.13 An active glycoside from V. prunifolium was later shown to bring about relaxation in both animal and human uteri.14
Scopoletin and esculetin, substances found in the bark of black haw, exert antispasmodic effects on uterine muscle. Scopoletin has an antispasmodic activity approximately one twentieth of that of papaverine; esculetin exerts approximately one eighth of the activity.15 The potency of the whole root is 0.05% that of papaverine.16
As in test tube studies, animal research has demonstrated complete relaxation of uterine tissue in rats with the administration of extracts from black haw, cramp bark (V. opulus), V. carlcephalum, and V. chenaulti. V. chenaulti was found to have twice the uterine-relaxant activity of the other species. Constituents have been identified in black haw and cramp bark that exert uterine-relaxant properties.17
Herbalists practicing in the United States and United Kingdom commonly recommend black haw, cramp bark, or both for painful menstrual cramps, threatened miscarriage, leg cramps, tension headaches, afterbirth pains, and muscle spasm. However, despite the praise from physicians of old and contemporary practitioners of botanical medicine, sadly no clinical trials have been conducted to evaluate the antispasmodic effects of either herb. Black haw appears to be relatively safe but has been given a restriction by the American Herbal Products Association (AHPA)—“Individuals with a history of kidney stones should use this herb cautiously”18—because of the presence of oxalates. (Cramp bark does not contain oxalates.) The AHPA does not say that the use of black haw or cramp bark is contraindicated during pregnancy or lactation.18
Dose and administration.
To prepare an infusion, or tea, simmer 2 or 3 teaspoons of bark in 8 oz of water for 10 minutes. Strain and drink 1 cup two or three times a day as needed. The dose for fluid extract (1:1) is 4 to 8 mL, taken three or four times a day.19
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