Thiamine combines with adenosine triphosphate (ATP) to form a coenzyme, thiamine pyrophosphate (thiamine diphosphate, cocarboxylase), which is necessary for carbohydrate metabolism.

- Thiamine is indicated for prevention and treatment of thiamine deficiency states.
- Deficiency of thiamine may lead to beriberi (dry or wet) or Wernicke's encephalopathy.
- Requirements may be increased and / or supplementation may be necessary in the following persons or conditions: Hyperthyroidism, Burns, Hemodialysis (chronic), Stress (prolonged), Infection or fever (chronic), Manual labor (heavy, for long periods of time), Hepatic - biliary tract disease, Intestinal disease (celiac - ileal resection, tropical sprue), Gastrectomy, Alcoholism.
- Some unusual diets, may not supply minimum daily requirements for thiamine. Supplementation is necessary in patients receiving total parenteral nutrition or undergoing rapid weight loss or in those with malnutrition, because of inadequate dietary intake.
- Recommended intakes for all vitamins are increased during pregnancy or breast feeding.
- Thiamine has been found to be useful for temporary metabolic correction or genetic enzyme deficiency diseases.

- Laboratory value alterations usually occurs only with large doses.
- In Wernicke's encephalopathy, thiamine should be administered prior to glucose.
- Sensitivity to thiamine.

Problems in humans have not been documented with intake of normal daily recommended amounts.

Those indicating need for medical attention:
Incidence rare: Anaphylactic reaction.

Usual adult, adolescent and pediatric dose:
Deficiency (prophylaxis) - Oral, amount based on normal daily recommended intakes:

Persons	mg
Adolescent and adult males	1.2 - 1.5
Adolescent and adult females	1 - 1.1
Pregnant females	1.5
Breast - feeding females	1.6
Birth to 3 years of age	0.3 - 0.7
4 to 6 years of age	0.9
7 to 10 years of age	1

Deficiency (treatment) - Usual adult and adolescent dose:
Beriberi (initial in mild or maintenance following severe) - Oral, 5 to 10 mg three times a day.
Genetic enzyme deficiency disease - Oral, 10 to 20 mg per day as a single dose (dosage of up to 4 grams per day in divided doses has been used).
Usual pediatric dose:
Beriberi (mild) - Oral, 10 mg per day.