This case report highlights the cutaneous effects of lithium. Dermatological side-effects have been reported since lithium has been used in the 70s. It mainly exacerbates psoriasis, sometimes leading to serious pustular or generalized forms or resistance to usual therapeutics. Psoriasis may also appear in subjects free from this disease, usually more frequently in people with a family history of psoriasis. Lithium can increase acne or induce acneiform eruptions, the treatment of which must avoid tetracycline antibiotics. Other erythematous pruritic rashes may occur as well as rare cases of severe skin disease, like exfoliative dermatitis or lupus-like syndromes. Dystrophic disorders of the nails and especially hair may occur. Xerosis can be mild but disturbing in every day life as in this case, in which compliance has been shattered for this reason. Cutaneous side-effects of lithium seem to be dose-dependent and can lead first to reduce serum lithium levels. If skin condition does not improve, lithium discontinuation might be the only possibility left, reintroduction usually leading to a relapse of the dermatologic disorder. At last, topical lithium has antiviral and positive cutaneous effects, now of interest in the dermatological field.