Summary of findings 1. Serenoa repens compared to placebo or no intervention.

Serenoa repens compared to placebo or no intervention
Patient or population: lower urinary tract symptoms due to benign prostatic hyperplasia Setting: outpatient (Australia, Asia, Europe, and the USA) Intervention: Serenoa repens Comparison: placebo/no treatment
Outcomes	№ of participants (studies)	Certainty of the evidence (GRADE)	Relative effect (95% CI)	Anticipated absolute effects* (95% CI)
				Risk with placebo/no treatment	Risk difference with Serenoa repens
Urologic symptom score Measured by IPSS scores (range 0 to 35) Higher scores indicate worse symptoms. Follow‐up: 3 to 6 months MCID: 3 points	1681 (9 RCTs)	⊕⊕⊕⊕ Higha	MD −0.90 (−1.74 to −0.07)	The mean score was 14.33.	MD 0.90 lower (1.74 lower to 0.07 lower)
Quality of life Measured by IPSS‐QoL score (range 0 to 6) Follow‐up: 3 to 6 months MCID: 0.5 points	1001 (5 RCTs)	⊕⊕⊕⊕ Higha	MD −0.20 (−0.40 to 0.00)	The mean score was 3.11.	MD 0.20 lower (0.40 lower to 0.00 lower)
Adverse events Cumulative incidence Follow‐up: 1 to 17 months MCID: relative risk reduction/increase of 0.25	2399 (12 RCTs)	⊕⊕⊕⊝ Moderateb	RR 1.01 (0.77 to 1.31)	164 per 1000	2 more per 1000 (38 fewer to 51 more)
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IPSS: International Prostate Symptom Score; MCID: minimal clinically important difference; MD: mean difference; QoL: quality of life; RCT: randomized controlled trial; RR: risk ratio.
GRADE Working Group grades of evidence High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

^aWe did not downgrade the certainty of the evidence for risk of bias as these results were robust following sensitivity analysis excluding studies at high risk of bias. 
^bWe did not downgrade the certainty of the evidence for risk of bias as these results were robust following sensitivity analysis excluding studies at high risk of bias. We downgraded one level due to imprecision as the CI included little to no benefit and also harms (based on a 25% relative risk reduction).