Dysmenorrhea is associated with painful uterine contractions, nausea, vomiting, and diarrhea. Pain is thought to be caused by the release of prostaglandin F2α in the menstrual fluid. The main treatments are nonsteroidal anti-inflammatory drugs (NSAIDs), prostaglandin inhibitors, and contraceptive pills. NSAIDs can be effective in relieving dysmenorrhea but commonly cause adverse side effects and are contraindicated in some people. Mefenamic acid is a mild analgesic and fever-reducing NSAID used for relief of moderate short-term menstrual pain. Peppermint (Mentha × Piperita, Lamiaceae) exerts its effect on the myometrium contractile activity by inhibiting prostaglandin F2α and oxytocin and has also been shown to have an analgesic and anti-inflammatory effect.1,2 In addition, menthol, a primary constituent in mint, reduces vomiting and diarrhea.3,4 The goal of this study was to compare the effects of peppermint oil and the NSAID mefenamic acid for relief of dysmenorrhea symptoms.
A prospective, randomized, crossover study was conducted for 2 months with 122 single, female Iranian university students aged 18-25 years who already had primary dysmenorrhea. Group 1 received 3 peppermint oil capsules (Colpermin™; Tillotts Pharma AG; Rheinfelden, Switzerland) once a day for 3 days after menstruation started, followed by a washout period during the next menstrual cycle. The actual dosage of peppermint oil was not disclosed. [Note: The Colpermin website states that each gastro-resistant hard-gelatin capsule contains 187 mg of peppermint oil.5] Then, in the third menstrual cycle, patients were given 1 capsule containing 250 mg mefenamic acid (Ponstan®; Razak Laboratories Co.; Tehran, Iran) every 8 hours for 3 days. Group 2 received the same treatments in reverse order.
There was no significant difference in age, the number of days of menstruation, age at first menstruation, or dysmenorrhea interval between groups. Patients were given questionnaires after taking each treatment. Pain intensity was assessed through visual analog scale (VAS) and dysmenorrhea timing through the Cox menstrual symptom scale. Bleeding amount was measured using a pictorial blood assessment chart (PBAC). The VAS and Cox scale were answered at the beginning and end of each menstruation. PBAC was completed on menstruation days. Patients were allowed to take sedatives 1 hour after treatment, but they had to record the intensity and duration of their pain first.
Consumption of both mefenamic acid and peppermint oil significantly reduced the severity of pain (P<0.05), and there was no significant difference between the 2 treatments. Mefenamic acid and peppermint oil both significantly reduced duration of pain (P<0.05); however, duration of pain was more greatly reduced by mefenamic acid than peppermint oil (P<0.05). Mefenamic acid significantly reduced bleeding (P<0.05), while there was a slight (nonsignificant) increase in bleeding after peppermint oil treatment (P>0.05). There was no significant difference in nausea and vomiting with the use of mefenamic acid (P>0.05), but both were significantly decreased by peppermint oil (P<0.05). Peppermint oil also showed a significantly greater reduction in diarrhea compared to mefenamic acid (13.5% and 3.8% decrease, respectively; P<0.05). Both groups had similar significant decreases in analgesic use during treatment periods (P<0.05).
The findings of this study show that peppermint oil can reduce the duration and severity of menstrual cramps. Mefenamic acid has been studied as a drug treatment for dysmenorrhea; yet, the results of this study show that peppermint oil has similar effects to mefenamic acid while achieving the additional benefits of significantly reducing nausea and vomiting. Due to the complications of mefenamic acid (some of which include gastrointestinal bleeding, ulcers, flatulence, indigestion, and stomach pain), peppermint oil may be a preferred treatment. Researchers urge future studies on peppermint oil for treatment of dysmenorrhea symptoms and suggest the use of higher dosages or treatment during the luteal phase of the fertility cycle.
1Jalilzadeh-Amin G, Maham M. Evaluation of pulegone on transit time and castor oil induced diarrhea in rat. Pharmaceutical Sciences. 2013;19(3):77-82.
2Taher YA. Antinociceptive activity of Mentha piperita leaf aqueous extract in mice. Libyan J Med. 2012;7(1). doi: 10.3402/ljm.v7i0.16205.
3Hiki N, Kaminishi M, Hasunuma T, et al. A phase I study evaluating tolerability, pharmacokinetics, and preliminary efficacy of L-menthol in upper gastrointestinal endoscopy. Clin Pharmacol Ther. 2011;90(2):221-228.
4Alves JGB, de Brito Rde CCM, Cavalcanti TS. Effectiveness of Mentha piperita in the treatment of infantile colic: A crossover study. Evid Based Complement Alternat Med. 2012;2012:981352. doi: 10.1155/2012/981352.
5What does Colpermin™ contain? Colpermin website. Available at: http://www.colpermin.eu/about-colpermin-sup-tm-sup-/what-does-colpermin-sup-tm-sup-contain-. Updated October 2015. Accessed April 16, 2017.