Change in lesion counts ‐ inflamed (percentage reduction from baseline)
Study	Azelaic acid (mean)	Placebo (mean)	P value
short term
Cunliffe 1989	Unclear, not reported	Unclear, not reported	P < 0.001, the results demonstrated significant difference favouring azelaic acid over placebo cream.
medium term
Cunliffe 1989	Unclear, not reported	Unclear, not reported	P < 0.0025, the results demonstrated significant difference favouring azelaic acid over placebo cream.
Katsambas 1989a	Unclear, not reported	Unclear, not reported	P < 0.05, the results demonstrated significant difference favouring azelaic acid over placebo cream.
long term
Cunliffe 1989	Long term: three months after start of treatment, unclear, not reported	Unclear, not reported	P < 0.001, the results demonstrated significant difference favouring azelaic acid over placebo cream.
Katsambas 1989a	Long term: three months after start of treatment, 72%	47%	P < 0.05, the results demonstrated significant difference favouring azelaic acid over placebo cream.
long term (split‐face trials)
Hayashi 2012	Long term: 12 weeks after start of treatment, 68.7%	54.5%	unclear, not reported