[A drink with an unexpected ending... Adverse reaction by tonic water: A case report].

Background: Quinine is an alkaloid with antipyretic and anti-infective properties, and also an ingredient in tonic waters. Adverse reactions have been reported with this product, such as photosensitivity, vasculitis, and contact dermatitis.

Case report: A 31-year-old male patient who, after 3-4 hours of consuming "Schweppes®" gin with tonic water, manifested ulcers on the lips and oral cavity, and a fixed erythematous lesion on the second phalanx of the hand, 24 hours later. Skin tests with aeroallergens and food were negative, and 48-hour patch tests were positive (quinine [++] and "Schweppes®" [++]). Based on the test findings, the diagnosis of an adverse reaction to quinine, contained in the tonic water, will be established.

Conclusions: Quinine can be found in other types of foods or medications, so it is important to establish an accurate diagnosis and offer adequate recommendations to the patient with the consumption of this product.