What is the difference between cosmetic and pharmaceutical use of azelaic acid?

Azelaic acid is approved worldwide as an Active Pharmaceutical Ingredient (API) for the treatment of acne and rosacea. Pharmaceutical (drug) products typically contain 20% (acne) or 15% (rosacea) azelaic acid and require a doctor’s prescription. For cosmetic use, a concentration below roughly 15% by weight is generally used, and no prescription is required. Pharmaceutical-grade azelaic acid requires a purity above 99%, which Azepur99® meets.