Chananeh 2018.

Study characteristics
Methods	Randomised controlled trial
Participants	Persian Gulf Shohada Hospital of Bushehr Hospital Participants: 100 multiparous women, aged 15 ‐ 44 years, with natural delivery complaining of moderate‐to‐severe postpartum pain as measured using VAS 2 hours after delivery; women with pain score > 4 enrolled Inclusion criteria: 1.Being Iranian; 2. can read and write; 3. vaginal delivery; 4. spontaneous exit of placenta and membranes; 5. Multiparous; 6. gestational age between 37 ‐ 42 weeks; 7. complained of moderate or severe pain after delivery; 8. feeding is started and will be continued; 9. mother age between 15 ‐ 44 years; 10. deliver a singleton and healthy baby Exclusion criteria: 1. Instrumental delivery or pressure on uterus; 2. 3rd or 4th degree laceration;.3. history of caesarian section or pelvic operation; 4. use of any narcotic drug during labor and delivery or used at least 4 hours ago; 5. used epidural or spinal anaesthesia during labour and delivery; 6. mother has any drug addiction; 7. maternal history of herbal drug allergy; 8. maternal history of chronic disease Exclusion criteria during trial: 1. herbal drug sensitivity in mother during study; 2. mother uses other methods or drugs to relieve pain during study. 3. mother is suffering serious complications after delivery (such as high blood pressure, severe bleeding after childbirth, fever, etc.); 4. breastfeeding discontinued for mother or baby reasons; 5. mothers withdraws consent
Interventions	1. Nigella sativa (500 mg capsule) + mefenamic acid (250 mg capsule), women received 4 tablets, 6 hourly for 24 hours; n = 50 2. Placebo + mefenamic acid (250 mg capsule), women received 4 tablets, 6‐hourly for 24 hours; n = 50
Outcomes	Severity and duration of pain measured using VAS before, and 1 hour after medication administered. Side effects
Notes	Dates of study: 05 May 2017 ‐ final date not available (information from trial registration) Sponsor: Faculty of Nursing and Midwifery, Shahid Behesti Medical Science University Declarations of interest: none stated. Abstract in English, full paper in Perisan. Author emailed 8 February 2020 Translation requested 22 July 2020
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised double‐blind clinical trial Method of randomisation not stated
Allocation concealment (selection bias)	Unclear risk	No information provided to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Low risk	All women received 1 capsule of mefenamic acid, women in the intervention group additionally received a capsule of Nigella Sativa, women in the control group received a capsule similar in appearance to the Nigella Sativa but without Nigella Sativa Paper states "mothers and investigators were blinded".
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Paper states "mothers and investigators were blinded"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Results reported for all randomised women
Selective reporting (reporting bias)	Low risk	Stated outcomes were reported. Trial registration available
Other bias	Unclear risk	Abstract only in English, full text required translation