Akhavan Amjadi 2009.

Methods	Parallel‐group RCT 47 women analysed, unclear how many randomised
Participants	Included: single women with moderate to severe primary dysmenorrhoea. Regular periods cycles and with medium to severe pain Excluded: women with any known disease, signs of vaginal infection, history of pelvic inflammatory disease, myoma or tumour, drug or plant allergies, stressful incidence (parental divorce, or relative deaths) in the past 6 months or during the treatment. Incomplete questionnaire or missed a dose Age: 18 to 30 years (mean 20.96) Source: student population Location: Iran, Gilan University
Interventions	Group 1: cinnamon powder (26 analysed) Group 2: placebo (21 analysed) Dosing regimen: 420 mg Total daily dose: 5 capsules per day up to 3 days after pain started for 2 consecutive menstrual cycles
Outcomes	Pain on a 0 to 3 scale.
Notes	The review author Vahid Seyfoddin (VS) translated this article from Persian to English
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: the method was unclear (study authors reported a formula).
Allocation concealment (selection bias)	Unclear risk	Comment: the method of allocation concealment was not reported.
Blinding (performance bias and detection bias) All outcomes	Low risk	Comment: triple blinded (patients, clinicians, and statisticians were all blinded). The placebo and cinnamon capsule were completely identical and were manufactured by the same company. They were packed in an identical package and were distinguishable by a code on the packets.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: the study authors did not state the initial number of participants randomised. The final number analysed was 47 (26 in cinnamon treated group and 21 in placebo).
Selective reporting (reporting bias)	Unclear risk	Comment: adverse effects were not reported.
Other bias	Low risk	Comment: we did not identify any other likely sources of bias.