Retinoids are valuable drugs in the dermatologic armamentarium, being employed in daily clinical practice. The text provides an in-depth update on the latest thinking on pharmacology, clinical use, side effects, and follow-up of retinoid therapy in dermatology; it also addresses topics related to retinoid use in special circumstances, such as vulnerable populations, concomitant surgery, and aesthetic procedures.CONTENTS: The background of retinoids * Mechanism of action of vitamin A * Mechanism of action of topical retinoids * Mechanism of action of isotretinoin * Mechanism of action of acitretin * Mechanism of action of bexarotene * Mechanism of action of alitretinoin * Effects of retinoids at the cellular level (differentiation, apoptosis, autophagy, cell cycle regulation, and senescence) * Effects of retinoids at the systemic level * New aspects of isotretinoin teratogenicity * Mucocutaneous side effects * Ophthalmologic side effects * Musculoskeletal side effects * Neurologic side effects * Psychiatric side effects * Gastrointestinal side effects * Endocrine and metabolic side effecs * Other systemic side effects: Cardiovascular, pulmonary, otolaryngorhinologic, genitourinary, renal, and immunologic * Retinoids in acne * Retinoids in hidradenitis suppurativa/acne inversa * Retinoids in rosacea * Retinoids in hair disorders * Retinoids in psoriasis * Retinoids in keratinization disorders * Retinoids in antiaging therapy * Retinoids in other skin diseases * Retinoids in lymphoma * Retinoids in cutaneous chemoprophylaxis * Guide to good clinical practice for vulnerable populations (infancy, childhood, fertile period, elderly) * Retinoids and concomitant surgery * Retinoids and concomitant aesthetic procedures * Laboratory and clinical follow-up * Teratogenicity and registry programs * Management of vitamin A and retinoid side effects * Future and novel unexplored indications of retinoids Published in association with the Journal of Dermatological Treatment.