Vitamin B1 (Thiamine)


  • Vitamin


  • Dietary supplement; water-soluble vitamin


  • Vitamin B1deficiency due to anorexia, nausea, vomiting, severe alcoholism

  • Impaired GI absorption in malabsorption syndromes

  • Beriberi

  • Unlabeled uses: mosquito repellant (?)



  • Pregnancy category A

  • Vitamin B1 deficiency is characterized by:

    • Weakness

    • Paresthesia

    • Hypotension

  • Patients with thiamine-deficiency may experience a sudden onset or worsening of Wernicke’s encephalopathy, characterized by:

    • Horizontal nystagmus

    • Bilateral sixth nerve palsy

    • Ataxia

    • Confusion

  • Wernicke’s encephalopathy may occur in:

    • Excessive alcoholism

    • Prolonged IV feeding

    • Hyperemesis gravidarum

    • Anorexia nervosa

    • Prolonged fasting

    • Refeeding after starvation.

  Adverse Reactions (Side Effects):

  • Relatively non-toxic in therapeutic doses

  • Sensitivity reactions may occur with excessive IV dosing.

  • Pruritis, urticaria, warmth sensation, weakness, sweating


  • Dietary sources: rice, grains, pork, beef, fresh peas and beans

  • Administered orally (tablets) or injection

  • Dietary supplementation (RDA: recommended daily allowance):

    • Adult males: 1.5mg per day

    • Adults females: 1.1mg per day

  • Beriberi: 10-20mg IM tid for 2 weeks, followed by 5-10mg oral thiamine daily for one month to saturate

  • Wet beriberi with myocardial failure: 10-30mg IV tid

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