Change in lesion counts ‐ comedones (reduction in number of lesions post‐intervention)
Study	Azelaic acid	Placebo	P value
long term
Barbareschi 1991	Long term: four months after start of treatment, 23	3	Unclear, the author did not test the difference between groups.
Barbareschi 1991	Four months after start of treatment, number of lesions reduction post intervention, scanning electron microscopy measured comedones: 9.4±6.93	0.1±3.14	0.05