A Case of Anaphylaxis to Intramuscular but Not to Oral Application of Thiamine (Vitamin B1).

We report a 78 year-old non-atopic female with polyneuropathy who started to receive monthly intramuscular injections of thiamine hydrochloride. She had an anaphylaxis after the fourth injection. Skin prick test (SPT) with pure commercially available aqueous preparations was positive for thiamine hydrochloride. A titrated, single blinded, placebo-controlled oral provocation test with thiamine hydrochloride was well tolerated. The patient was then diagnosed as compartment allergy with hypersensitivity to parenteral but not to oral thiamine. Because in our patient, oral intake of thiamine has never been reported to lead to any adverse reaction. Oral tolerability might be due to the uptake mechanism of thiamine in the gastrointestinal system.