addition, no differences between different birth control pill preparations were found. norplant and depo-provera are also effective, since these methods often induce amenorrhea. the intrauterine system (mirena iud) may be useful in reducing symptoms. other a review indicated the effectiveness of transdermal nitroglycerin. reviews indicated magnesium supplementation seemed to be effective. a review indicated the usefulness of using calcium channel blockers. heat is effective compared to nsaids and is a preferred option by many patients, as it is easy to access and has no known side effects. tamoxifen has been used effectively to reduce uterine contractility and pain in dysmenorrhea patients. there is some evidence that exercises performed 3 times a week for about 45 to 60 minutes, without particular intensity, reduces menstrual pain. alternative medicine there is insufficient evidence to recommend the use of many herbal or dietary supplements for treating dysmenorrhea, including melatonin, vitamin e, fennel, dill, chamomile, cinnamon, damask rose, rhubarb, guava, and uzara. further research is recommended to follow up on weak evidence of benefit for: fenugreek, ginger, valerian, zataria, zinc sulphate, fish oil, and vitamin b1. a 2016 review found that evidence of safety is insufficient for most dietary supplements. there is some evidence for the use of fenugreek. one review found thiamine and vitamin e to be likely effective. it found the effects of fish oil and vitamin b12 to be unknown. reviews found tentative evidence that ginger powder may be effective for primary dysmenorrhea. reviews have found promising evidence for chinese herbal medicine for primary dysmenorrhea, but that the evidence was limited by its poor methodological quality. a 2016 cochrane review of acupuncture for dysmenorrhea concluded that it is unknown if acupuncture or acupressure is effective. there were also concerns of bias in study design and in publication, insufficient reporting (few looked at adverse effects), and that they were inconsistent. there are conflicting reports in the literature, including one review which found that acupressure, topical heat, and behavioral interventions are likely effective. it found the effect of acupuncture and magnets to be unknown. a 2007 systematic review found some scientific evidence that behavioral interventions may be effective, but that the results should be viewed with caution due to poor quality of the data. spinal manipulation does not appear to be helpful. although claims have been made for chiropractic care, under the theory that treating subluxations in the spine may decrease symptoms, a 2006 systematic review found that overall no evidence suggests that spinal manipulation is effective for treatment of primary and secondary dysmenorrhea. valerian, humulus lupulus and passiflora incarnata may be safe and effective in the treatment of dysmenorrhea. tens a 2011 review stated that high-frequency transcutaneous electrical nerve stimulation may reduce pain compared with sham tens, but seems to be less effective than ibuprofen. surgery one treatment of last resort is presacral neurectomy. epidemiology dysmenorrhea is one of the most common gynecological conditions, regardless of age or race. it is one of the most frequently identified causes of pelvic pain in those who menstruate. dysmenorrhea is estimated to affect between 50% and 90% of female adolescents and women of reproductive age. another report states that estimates can vary between 16% and 91% of surveyed individuals, with severe pain observed in 2% to 29% of menstruating individuals. reports of dysmenorrhea are greatest among individuals in their late teens and 20s, with reports usually declining with age. the prevalence in adolescent females has been reported to be 67.2% by one study and 90% by another. it has been stated that there is no significant difference in prevalence or incidence between races, although one study of hispanic adolescent females indicated an elevated prevalence and impact in this group. another study indicated that dysmenorrhea was present in 36.4% of participants, and was significantly associated with lower age and lower parity. childbearing is said to relieve dysmenorrhea, but this does not always occur. one study indicated that in nulliparous individuals with primary dysmenorrhea, the severity of menstrual pain decreased significantly after age 40. a survey in norway showed that 14 percent of females between the ages of 20 to 35 experience symptoms so severe that they stay home from school or work. among adolescent girls, dysmenorrhea is the leading cause of recurrent short-term school absence.