A rare aspect of commonly administered vitamin B12 injection therapy in primary care: Acneiform eruption

Vitamin B12 deficiency is commonly encountered in primary care and is usually associated with inadequate dietary intake. Although intramuscular replacement therapy is widely used, it may rarely lead to dermatological adverse effects, particularly acneiform eruptions. In this report, we present a 26-year-old female patient who applied to a family medicine outpatient clinic and received intramuscular cyanocobalamin therapy for five consecutive days due to vitamin B12 deficiency. In the second week of treatment, non-pruritic papulopustular eruptions developed, initially on the back and chest and later spreading to the face and neck. The clinical findings were consistent with an acneiform eruption induced by vitamin B12 therapy. This case highlights that rare dermatological adverse effects should be considered during the frequent use of vitamin B12 therapy in primary care settings.