Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects (tretinoin 0.01%)
Systematic review	344 people with mild to moderate photodamage 2 RCTs in this analysis	Burning or stinging 24 weeks 36/173 (21%) with topical tretinoin 0.01% (once-daily for 24 weeks) 18/171 (11%) with vehicle cream (once-daily for 24 weeks)	RR 1.99 95% CI 1.20 to 3.32	Small effect size	vehicle cream
Adverse effects (tretinoin 0.05%)
Systematic review	349 people 2 RCTs in this analysis	Erythema 24 weeks 60/178 (34%) with topical tretinoin 0.05% (once-daily for 24 weeks) 16/171 (9%) with vehicle cream (once-daily for 24 weeks)	RR 3.58 95% CI 1.99 to 6.46	Moderate effect size	vehicle cream
Systematic review	349 people 2 RCTs in this analysis	Scaling/dryness 24 weeks 115/178 (65%) with topical tretinoin 0.05% (once-daily for 24 weeks) 49/171 (29%) with vehicle cream (once-daily for 24 weeks)	RR 2.23 95% CI 1.72 to 2.88	Moderate effect size	vehicle cream
Systematic review	349 people 2 RCTs in this analysis	Burning and stinging 24 weeks 69/178 (39%) with topical tretinoin 0.05% (once-daily for 24 weeks) 18/171 (11%) with vehicle cream (once-daily for 24 weeks)	RR 3.75 95% CI 2.35 to 5.98	Moderate effect size	vehicle cream
Adverse effects (tretinoin 0.1%)
Systematic review	76 people with moderate to severe photodamage of the face and forearms Data from 1 RCT	Erythema 48 weeks 16/36 (44%) with topical tretinoin 0.1% (once-daily for 48 weeks) 0/40 (0%) with vehicle cream (once-daily for 48 weeks)	RR 36.57 95% CI 2.27 to 588.35	Large effect size	vehicle cream
RCT	45 people with moderate to severe facial photodamage	Skin erythema 1 month with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P = 0.0005 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Peeling 1 month with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P <0.0001 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Dryness 1 month with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P <0.0001 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Itching 1 month with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P = 0.0005 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Burning/stinging 1 month with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P <0.0001 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Peeling 6 months with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P = 0.001 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel
RCT	45 people with moderate to severe facial photodamage	Dryness 6 months with tretinoin 0.1% (microsphere gel preparation; applied once-daily for 6 months) with vehicle gel (applied once-daily for 6 months) Absolute results not reported	P = 0.007 Method of randomisation and allocation concealment were unclear	Effect size not calculated	vehicle gel