The present invention concerns a pharmaceutical composition comprising 0.3% by weight of adapalene or a pharmaceutically acceptable salt thereof and 2.5% by weight of benzoyl peroxide, as active ingredients, for its use by topical administration in the treatment of inflammatory acne lesions. The present invention further concerns regimen for the therapeutic treatment of acne lesions in subjects afflicted with severe acne. The regimen includes topically applying to a subject's skin, as active ingredients, 0.3% by weight adapalene and 2.5% by weight benzoyl peroxide, combined in a single formula that delivers the active ingredients together. The single formula can for example be applied once or twice daily for a period of 8 to 12 weeks.