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

From the Guidelines

For adults taking thiamine as a supplement via intramuscular (IM) injection, the recommended dose is 2 mg IM, as indicated by the study published in Pediatrics in 2016 1.

Key Considerations

• The dose may be repeated every 30–60 minutes if necessary, but this should be done under medical supervision.
• Alternatively, a dose of 0.05–0.1 mg/kg or 0.1 mg/kg IM can be considered, but the fixed dose of 2 mg IM is more straightforward for adult supplementation.

Administration and Safety

• IM thiamine injections should be administered by healthcare professionals due to potential risks such as pain at the injection site, bleeding, and rare allergic reactions.
• Oral thiamine supplements are generally recommended for routine supplementation needs, as they are safer, more convenient, and typically sufficient for healthy adults, with a typical dose of 1.1-1.2 mg daily.

Clinical Context

• Thiamine is crucial for carbohydrate metabolism and neurological function, and its deficiency can lead to severe conditions like beriberi or Wernicke-Korsakoff syndrome.
• However, for adults without a diagnosed deficiency or specific medical need, oral supplementation is preferred over IM injections for routine thiamine supplementation.

From the FDA Drug Label

In the treatment of beriberi, 10 to 20 mg of thiamine hydrochloride are given IM three times daily for as long as two weeks. Patients with neuritis of pregnancy in whom vomiting is severe enough to preclude adequate oral therapy should receive 5 to 10 mg of thiamine hydrochloride IM daily. In the treatment of Wernicke-Korsakoff syndrome, thiamine hydrochloride has been administered IV in an initial dose of 100 mg, followed by IM doses of 50 to 100 mg daily until the patient is consuming a regular, balanced diet.

The recommended dose of thiamine for adults as a supplement is not explicitly stated in the label for general supplementation. However, for specific conditions, the doses are:

• Beriberi: 10 to 20 mg IM three times daily
• Neuritis of pregnancy: 5 to 10 mg IM daily
• Wernicke-Korsakoff syndrome: 50 to 100 mg IM daily 2

From the Research

Thiamine Supplementation for Adults

• The provided studies do not specify the exact dose of thiamine to be taken intramuscularly (IM) as a supplement for adults 3, 4, 5, 6, 7.
• However, one study suggests that high-dose thiamine administered intramuscularly may be effective in treating essential tremor, with no relevant side effects reported 6.
• The dose used in this study is not specified, but it is mentioned as "high-dose" thiamine.
• Another study discusses the importance of thiamine supplementation in patients with thiamine deficiency syndromes, but does not provide specific dosage recommendations for IM administration 4.
• It is essential to note that thiamine deficiency can cause severe health issues, and supplementation should be considered for individuals at risk, such as those with malnutrition, alcohol use disorders, or critical illnesses 3, 5, 7.

Considerations for Thiamine Supplementation

• Thiamine is an essential cofactor for energy production and can help prevent deficiency disorders, which can affect various systems in the body 3, 5, 7.
• The total body stores of thiamine are relatively small, and deficiency can develop quickly due to inadequate nutrition or increased urinary excretion 3.
• Clinicians should be aware of patients at risk for thiamine deficiency and consider supplementation to prevent or treat deficiency disorders 5, 7.