As amazing as this sounds there have been few cases where vitamin B6 and/or B12 supplements have caused acne. Here is what one report has to say:
Deterioration of acne vulgaris or eruption of an acneiform exanthema could be established during treatment with vitamin B6 and/or vitamin B12 in 14 patients. Females were by far the more frequently affected. The appearance of skin symptoms, even outside the age groups typically affected by acne vulgaris is characteristic. The clinical appearance of acneiform exanthema occurring during treatment with vitamin B6 or B12 consists of loosely disseminated small papules or papulopustules on the face (especially on the forehead and chin), on the upper parts of the back and chest and spreading to the upper arm. The pathogensis of the change is not yet certain. The acneiform rash generally fades within a short time after vitamin B6 or vitamin B12 treatment has been stopped.
The problem of vitamin B6/B12 acne. A contribution on acne medicamentosa (author’s transl)
Braun-Falco O, Lincke H.
Medications and other exogenous factors are known to be capable of exacerbating acne or precipitating acneiform eruptions. This case illustrates an eruption resembling acne rosacea that was temporally associated with daily ingestion of high-dose B vitamin supplement. The eruption failed to respond to the usual treatment regimens for rosacea, but promptly improved when use of the vitamin supplement was discontinued.
Acneiform eruption due to “megadose” vitamins B6 and B12.
The Netherlands Pharmacoliqilance Centre reported that few people have developed acne after receiving injections of B6 and/or B12 vitamins.
Click here to read their report about vitamins B6 and B12 and acne (PDF file).
It seems that the mechanism how B6 or B12 vitamins cause acne are unknown. The only theory I’m aware of is from Dr. Lit-Hung Leung in his study on the use of vitamin B5 as adult acne treatment. He said that as vitamins B6, 6 and 12 often work together and increase in supply of vitamins B6 and B12 would reduce the body’s storages of B5. Here is more information about vitamin B5 treatment on adult acne .
Anyway, the bottom line remains that the cases where vitamins B6 and/or B12 have caused acne are rare and most likely you don’t have to worry about it.