Hydroxocobalamin: An Effective Treatment for Flushing and Persistent Erythema in Rosacea.

Background: Expression of inducible nitric oxide synthase (NOS) is higher in rosacea skin samples than in normal skin controls. Hydroxocobalamin is a potent inhibitor of all isoforms of NOS, capable of reducing the vasodilatations induced by nitric oxide.

Objective: We aimed to evaluate the role of hydroxocobalamin in treating facial flushing and persistent erythema of rosacea.

Methods: Thirteen patients with rosacea who displayed facial flushing and persistent erythema received 1 to 4 weekly intramuscular injections of hydroxocobalamin 1 to 2 mg. The outcomes were measured using the Clinician's Erythema Assessment (CEA) by photography and an infrared thermometer to evaluate the difference in skin surface temperature (SST) of the cheeks before and after treatment.

Results: Thirty minutes after the first dose of intramuscular injection of hydroxocobalamin, the mean CEA significantly reduced from 2.2± 0.6 to 1.2±0.4 (<0.001), and average SST also significantly reduced from 36.7±0.70°C to 36.2±0.61°C (<0.001) on the cheeks.

Conclusion: In our patient sample, intramuscular administration of hydroxocobalamin was effective for immediate reduction of facial erythema associated with rosacea.