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Vitamin B1 Side Effects

Generic Name: thiamine

Note: This page contains side effects data for the generic drug thiamine. It is possible that some of the dosage forms included below may not apply to the brand name Vitamin B1.

For the Consumer

Applies to thiamine: capsule, solution, tablet, tablet enteric coated

As well as its needed effects, thiamine (the active ingredient contained in Vitamin B1) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking thiamine, check with your doctor immediately:

Rare - Soon after receiving injection only
  • Coughing
  • difficulty in swallowing
  • hives
  • itching of skin
  • swelling of face, lips, or eyelids
  • wheezing or difficulty in breathing

For Healthcare Professionals

Applies to thiamine: compounding powder, injectable solution, oral tablet


Local side effects have included tenderness and induration at the injection site following intramuscular use.[Ref]


Hypersensitivity side effects have included a feeling of warmth, pruritus, urticaria, weakness, sweating, nausea, restlessness, tightness of the throat, angioneurotic edema, cyanosis, pulmonary edema, and hemorrhage into the gastrointestinal tract. Anaphylaxis has been reported, especially after repeated injection. Collapse and death have also been reported.[Ref]


1. "Product Information. Vitamin B1 (thiamine)." Dixon-Shane Inc, Philadelphia, PA.

It is possible that some side effects of Vitamin B1 may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.