Summary of findings for the main comparison. Biotin compared to placebo for infantile seborrhoeic dermatitis (including cradle cap).

Biotin compared to placebo for infantile seborrhoeic dermatitis (including cradle cap)
Patient or population: infantile seborrhoeic dermatitis (including cradle cap) Setting: paediatric department in Israel (Erlichman 1981) and Australia (Keipert 1976) Intervention: biotin Comparison: placebo
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with placebo	Risk with biotin
Change in severity	See comment	See comment	—	39 (2 RCTs) randomised but only 35 included in analysis	⊕⊝⊝⊝ Very lowa	Change in severity assessed using different scales and metrics. Erlichman 1981 reported duration of rash 1.3 (SD 0.9) months in the placebo group and 1.4 (SD 0.8) months in the biotin group, but the study did not report an explicit measure of change in severity. Keipert 1976 did not report raw data for changes in severity but reported no statistical difference between biotin and placebo. There was "a strongly significant difference in the quantitative measure for whatever was used first" (likely due to effectiveness of the topical steroid).
Adverse events	See comment	See comment	—	39 (2 RCTs)	—	Not reported.
Quality of life	—	—	—	—	—	Not measured.
*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; RCT: randomised controlled trial; SD: standard deviation.
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.

^aEvidence downgraded by three levels to very low because of serious risk of bias (incomplete outcome reporting in Erlichman 1981 and in Keipert 1976 the manufacturer analysed the data), serious imprecision (small numbers and wide confidence intervals) and serious indirectness (in Keipert 1976 study infants were also treated with topical betamethasone cream).