What is the recommended intramuscular (IM) dose of thiamine (Vitamin B1)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: May 3, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Research

The recommended intramuscular (IM) dose of thiamine is 100-250 mg daily for 3-5 days for prevention in alcoholic patients or malnourished individuals, and 500 mg three times daily for 2-3 days, followed by 250 mg daily for 3-5 days for treatment of Wernicke's encephalopathy, as supported by the most recent and highest quality study 1. When administering thiamine IM, it is essential to inject deeply into a large muscle like the gluteus maximus or vastus lateralis. Thiamine is water-soluble, and excess is excreted in urine, making toxicity rare. However, anaphylactic reactions can occur with IV administration, which is why slower infusion rates are recommended when using that route. Some key points to consider when administering thiamine include:

  • The dose and duration of treatment may vary depending on the individual patient's needs and response to treatment.
  • Thiamine should be administered promptly in patients with suspected Wernicke's encephalopathy, as delayed treatment can lead to poor outcomes.
  • The use of thiamine in combination with other vitamins and nutrients, such as magnesium, may be beneficial in certain cases.
  • After the initial IM treatment course, patients should transition to oral thiamine (50-100 mg daily) for maintenance therapy, as supported by studies 2, 3. It is crucial to note that the evidence for thiamine dosing is largely based on clinical experience and expert opinion, rather than high-quality randomized controlled trials, as highlighted in studies 4, 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.