Vitamin B1 Side Effects

Generic name: thiamine

Medically reviewed by Drugs.com. Last updated on Mar 30, 2025.

Note: This document provides detailed information about Vitamin B1 Side Effects associated with thiamine. Some dosage forms listed on this page may not apply specifically to the brand name Vitamin B1.

Applies to thiamine: solution, tablet.

Serious side effects of Vitamin B1

Along with its needed effects, thiamine (the active ingredient contained in Vitamin B1) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking thiamine:

Rare side effects

- 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 capsule, oral tablet.

Local adverse events

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

Hypersensitivity

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]

Further information

Vitamin B1 side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer