The demographic and clinical characteristics of patients with vitamin B12-induced acneiform eruption (BIAE) were reported in study data published in Dermatologic Therapies. Time to eruption onset was shorter in patients who received intramuscular vs oral vitamin B12, although time from drug discontinuation to BIAE improvement was not significantly different between the intramuscular and oral groups.

Investigators conducted a retrospective cohort study of patients with BIAE admitted to the dermatology departments of participating hospitals in Turkey. To ensure that the acneiform eruptions were caused by vitamin B12, the following inclusion criteria were applied: (1) the eruption occurred within days to weeks after vitamin B12 administration; (2) the eruption disappeared when vitamin B12 was discontinued; (3) the eruption consisted of monomorphous papulopustular lesions without comedones or cystic lesions. Patients who did not fit these criteria were excluded. Demographic and clinical information were collected for each participant, including age, sex, medication history, previous exposure to vitamin B12, morphology and distribution of the eruption, and treatment used for eruption. 

A total of 32 patients were enrolled, of whom 20 (62.5%) were women. Mean age was 28 ± 11 years. The majority of patients presented with lesions without additional symptoms, and mild itching and burning were reported by 12 (37.5%) and 4 (15.3%) patients, respectively. Recovery time did not differ between patients who were asymptomatic and patients who reported itching or burning (P >.05). More than half of patients had received intramuscular vitamin B12 (n=18; 56.25%), and 14 (43.75%) received an oral combination of vitamin B1, B6, and B12. Mean dose of vitamin B12 was 1.6 ± 1.2 mg in the intramuscular group and 7.1 ± 2.6 mg in the oral group. Intramuscular administration was associated with shorter time to eruption (P <.05). However, mean time between drug discontinuation and eruption improvement was not different in the oral and intramuscular groups (P >.05). In the total cohort, mean time between first intake and symptom onset was 11 ± 6 days (range, 1-30); mean time between discontinuation and considerable improvement was 7 ± 3 days (range, 4-15). Eruptions were generalized to the face, neck, chest, and back in 8 patients (25%), limited to the neck and chest in 13 (40.6%), limited to the neck, chest, and back in 8 (25%), and limited to the face in 3 (9.3%). In patients with itching and/or burning, eruptions were managed using topical clindamycin or topical benzoyl peroxide-erythromycin. Asymptomatic patients were followed-up without treatment.

Although prior studies assert that BIAE improvement may take 1-8 weeks, these data suggest that considerable improvement may be achieved 7± 3 days after discontinuation. The pathogenesis of BIAE remains unclear; future studies are necessary to assess the immunological, endocrine, and vascular impact of vitamin B12. As a study limitation, investigators noted that patients in the oral administration group (n=18) received a combination of vitamin B1, B6, and B12. In this group, the effect of vitamin B12 could not be isolated, and acneiform eruption may have been a product of the combined vitamins. However, this study represents the largest effort to assess vitamin B-12-related acneiform eruptions in patients with intramuscular or oral B12 intake. “Given the limited number of studies focusing on the subject, vitamin B12 seems to be an underestimated cause of acneiform drug eruptions,” investigators wrote.

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Elmas ÖF, Metin MS, Özyurt K, Atasoy M. Vitamin B12: an underestimated cause of acneiform drug eruption [published online May 7, 2020]. Dermatol Ther. doi: 10.1111/dth.13531