Hypersensitivity reactions to Vitamin B1 e.g. sweating, tachycardia, skin reactions with itching and urticaria are very rare. Gastrointestinal complaints e.g. nausea, vomiting, diarrhea or abdominal pain may occur.
Administration of Vitamin B12 in doses greater than 10 mcg daily may produce haematological response in patients with folate deficiency.