Indications
Thiamine (vitamin B1) is used to prevent and treat vitamin B1 deficiency, including beriberi, and the nerve and brain problems it can cause. It is given to people at risk, such as those with heavy alcohol use, poor diet, long-term vomiting, after weight-loss surgery or on dialysis. Injections are used urgently for Wernicke’s encephalopathy (confusion, unsteady walking and eye movement problems caused by severe deficiency). Thiamine is also found in many multivitamin and B-complex products.
How It Works
Thiamine is turned in the body into thiamine pyrophosphate, which enzymes need to release energy from carbohydrates. Nerves, the brain and the heart depend heavily on this energy, which is why lack of thiamine affects them first.
Dosage and Administration
For mild deficiency in adults, a usual dose by mouth is 10 to 25 mg a day; for more definite deficiency or people with heavy alcohol use, doctors often use 100 mg one to three times a day. For prevention, follow the dose on the label of the multivitamin or B-complex product. Injections are given by a doctor or nurse, as prescribed, usually in hospital.
Interactions
Thiamine has few interactions. Alcohol reduces its absorption. Long-term use of diuretics such as Furosemide can increase thiamine loss. When glucose is given to a person at risk of deficiency, thiamine should be given first to avoid triggering Wernicke’s encephalopathy.
Contraindications
Do not use if you are allergic to thiamine or any ingredient in the product.
Side Effects
Tablets are usually very well tolerated; mild stomach upset can occur. Injections may cause pain at the injection site and, rarely, serious allergic reactions.
Get urgent medical help if you have swelling of the face or throat, difficulty breathing, widespread itching or rash, or feel faint after an injection.
Pregnancy and Lactation
Thiamine is needed in pregnancy and breastfeeding and is safe at usual dietary or supplement amounts. Severe vomiting in pregnancy can lead to deficiency, and your doctor may prescribe extra thiamine.
Precautions and Warnings
Injections should be given where treatment for allergic reactions is available. Confusion, unsteady walking or eye problems in someone with heavy alcohol use or long-term vomiting is an emergency needing hospital care. Eat a balanced diet that includes whole grains, pulses and meat or fish.
Overdose
Excess thiamine taken by mouth is passed in the urine, and overdose is very unlikely to cause harm. Seek medical advice if a very large amount is taken or symptoms occur.
Therapeutic Class
Vitamin (water-soluble vitamin B1).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children. Injections and infusions are stored as directed on the pack.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.