Adverse skin reactions to vitamin K1: report of 2 cases

Vitamin K is essential to the biosynthesis of prothrombin and other clotting factors (VII, IX and X), and is mostly used for the prophylaxis of bleeding disorders, mainly in patients with hepatic disfunction (1). 4 different pharmacological forms exist: the natural form K1 (phytomenadione); K₂ (menaquinone), which is derived from intestinal bacterial action; K₃ (menadione); and K₄ (menadiol). The latter 2 are synthetic products. In Italy, only vitamin K1 is marketed (2).
Adverse cutaneous reactions to vitamin K are rare; 2 are mainly reported: an erythematous plaque (3, 4) or pseudo-scleroderma (5) at the injection site. Contact dermatitis and localized urticarial lesions have also been described (2).