Contact dermatitis in patients suffering acne is raising. These reactions are provoked by different sensitizing substances used in the treatment of acne. The Authors review the diverse possibilities of sensitisation in acne patients: contact dermatitis, primary irritation, photoallergy and phototoxicity, and "dermatitis by general administration of the allergen". The diverse acneiform contact dermatitis are reviewed and classified. The importance of acne venenata or contact acne--professional or no--, and different acneiform contact eruptions or by ingestion, is emphasized.