Vitamin B12 (hydroxocobalamin, cyanocobalamin): advise patients with known cobalt allergy to be vigilant for sensitivity reactions

As vitamin B12 contains cobalt, healthcare professionals prescribing these products to patients with known cobalt allergy should advise patients to be vigilant for signs and symptoms of cobalt sensitivity (e.g skin reactions such as a rash or hives) and treat as appropriate.

SPS commentary:

Cobalt sensitivity reactions typically present with cutaneous symptoms of chronic or subacute allergic contact dermatitis. Infrequently, cobalt allergy may trigger an erythema multiforme-like reaction. Symptom onset may be immediate or delayed up to 72 hours post-administration.

Medicines and Healthcare products Regulatory Agency