Primary dysmenorrhea, or menstrual pain, can disrupt a woman’s daily activities. Nonsteroidal anti-inflammatory drugs are used to control the symptoms of dysmenorrhea; however, they can produce adverse effects when used over a long period of time. Several medicinal plants have been shown to benefit dysmenorrhea. Cinnamon (Cinnamomum zeylanicum, Lauraceae) bark, which has antioxidant, antibacterial, and anti-inflammatory properties, is used to treat indigestion, abdominal cramps, intestinal spasms, and nausea, among other issues. These authors conducted a double-blind, randomized, clinical trial to investigate the effects of cinnamon on primary dysmenorrhea.
The study included 80 single, female college students with primary dysmenorrhea who lived in dormitories at Isfahan University of Medical Sciences in Isfahan, Iran. The participants had regular menstrual cycles (21 to 38 days) with mild to moderate menstrual pain and no history of gynecological or systemic diseases or allergies to herbs. Those who were using hormonal or analgesic drugs were not eligible, and participants who used drugs during the study did not comply with treatment or had a possible allergic reaction were excluded.
Participants were evenly divided into two groups of 40. The cinnamon group took 1,000 mg cinnamon three times daily during the first 72 hours of menstruation for two consecutive menstrual cycles. The placebo group took 1,000 mg of starch three times daily. A visual analog scale was used by the participants before treatment and after each treatment, period to rate the severity of their pain, with 0 indicating no pain and 10 representing unbearable pain.
Included in the final analysis were 28 participants in the cinnamon group and 30 in the placebo group. Reasons for the dropouts included inadequate adherence or refusal or avoidance of the study products (altogether seven participants in the cinnamon group and six in the placebo group), use of other pain medicine (three in the cinnamon group and four in the placebo group), and allergy (two in the cinnamon group). At baseline, the mean ages of the analyzed participants in the two groups were 22.2 ± 2.2 years in the cinnamon group and 22.3 ± 2.7 years in the placebo group.
Menstrual pain decreased in the cinnamon group from a mean score of 5.7 before use to 3.6 during the first cycle and to 3.2 in the second cycle. In the placebo group, the pain decreased from a mean score of 5.8 to 5 in the first cycle and to 4.9 in the second cycle. A repeated measure analysis of variance showed a significant decrease in the intensity of dysmenorrhea in both groups (P<0.001) and a significant between-group difference in pain reduction over time (P=0.02). Compared with baseline, the reduction in pain in the cinnamon group was significantly greater than in the placebo group in the first cycle (P=0.001) and in the second cycle (P=0.002).
The authors attribute the decrease in pain seen in the placebo group to the placebo effect, including the psychological benefit of interaction with a researcher. They suggest that the placebo effect might have declined if the study had continued for more than two menstrual cycles.
Concluding that cinnamon significantly reduced the severity of menstrual pain, the authors recommend the use of cinnamon in women with primary dysmenorrhea. They note that studies directly comparing cinnamon to drugs used for dysmenorrhea would also be of interest.
Jahangirifar M, Taebi M, Dolatian M. The effect of cinnamon on primary dysmenorrhea: A randomized, double-blind clinical trial. Complement Ther Clin Pract. November 2018;33:56-60. doi: 10.1016/j.ctcp.2018.08.001.