Thiamine is vitamin B1. It is used to treat and prevent thiamine deficiency — most importantly in people with alcohol dependence, where a shortage can cause serious and sometimes permanent brain damage. It is also used in malnutrition, malabsorption and heart failure, and is available as tablets and injections.
What is Thiamine?
Thiamine and vitamin B1 are the same nutrient. It was the first B vitamin identified, which is how it got the number 1. Supplements contain thiamine hydrochloride or thiamine mononitrate — both work.
Thiamine appears in South African products as single-ingredient tablets (commonly 100 mg), in B-complex products such as BCo and Neurobion, and in injections. Read your own pack for the strength.
The body converts thiamine into thiamine pyrophosphate, an essential co-factor in the reactions that release energy from carbohydrate. Its roles:
- Carbohydrate metabolism — converting glucose into usable energy. This is its central function, and everything else follows from it.
- Nerve function. Nerves and brain depend heavily on a steady glucose supply, so they suffer first when thiamine runs short.
- Heart muscle function.
- Producing neurotransmitters.
The body stores very little thiamine — enough for roughly two to three weeks. Unlike fat-soluble vitamins that accumulate over months, a shortfall develops quickly when intake stops or requirements rise. That short reserve is why thiamine deficiency can appear within weeks in someone who stops eating properly, and why it is treated urgently rather than gradually.
What is Thiamine commonly used for?
- Treating and preventing thiamine deficiency.
- Alcohol dependence and alcohol withdrawal — the most common reason it is prescribed in South Africa, and the most important. Alcohol impairs thiamine absorption, storage and use, while often displacing food.
- Wernicke’s encephalopathy, a neurological emergency caused by acute deficiency, treated with high-dose injections.
- Beriberi, the classic deficiency disease affecting nerves (“dry beriberi”) and the heart (“wet beriberi”).
- Malnutrition, and refeeding, where thiamine must be given before or alongside nutrition.
- Malabsorption, including after bariatric surgery and in inflammatory bowel disease.
- Persistent vomiting, including severe pregnancy sickness (hyperemesis gravidarum).
- Heart failure on long-term diuretics, which increase thiamine loss.
- Dialysis, where water-soluble vitamins are lost during treatment.
It corrects a shortfall rather than adding benefit beyond that. Thiamine is present in wholegrains, pork, legumes, nuts, seeds and fortified cereals, and deficiency is uncommon on a varied diet.
It is not an energy supplement. Because thiamine is central to energy metabolism, it is widely marketed and bought that way — and this is the most common misunderstanding about it. A deficiency causes fatigue, and correcting it resolves that fatigue. Taking thiamine when your levels are normal does not produce energy. Persistent tiredness has many causes — anaemia, thyroid disease, diabetes, sleep apnoea, depression — none of which are addressed by a vitamin you do not lack.
Who commonly looks for Thiamine and why
- People with alcohol dependence, or their families — often after a doctor or clinic recommended it.
- People reducing or stopping alcohol, where thiamine is a standard part of safe withdrawal.
- People with poor or restricted diets, including some older adults.
- People with tingling, numbness or burning in the hands or feet.
- People with malabsorption, or after bariatric surgery.
- People with heart failure, particularly on diuretics.
- Pregnant women with severe vomiting.
- People on dialysis.
- People seeking more energy, who are usually better served by finding the actual cause.
What to check on the label before taking Thiamine
- The amount of thiamine per tablet, which varies widely — from around 10 mg to 300 mg.
- The recommended daily amount, and how many tablets that means.
- Whether it is a single vitamin or part of a B-complex, and whether you already take something containing thiamine.
- The form — hydrochloride or mononitrate; both work.
- Whether it is oral or injectable. Injections should be given by a healthcare professional.
- Any advice on taking it with food.
- The expiry date and storage, as thiamine degrades with heat and light.
Adults need only around 1 mg daily. Supplements often contain many times that, which is generally not a problem — thiamine is water-soluble and surplus is excreted.
Safety, interactions and when to seek professional advice
Thiamine is among the safest vitamins to supplement. It is water-soluble, the body excretes what it does not need, and no upper limit has been established because oral toxicity is essentially not seen. This is a genuine contrast with vitamin B6, where excess causes nerve damage — worth knowing if you take a B-complex containing both.
Side effects are uncommon and usually mild. Serious allergic reactions have been reported with injected thiamine, which is one reason injections are given in clinical settings.
But safety is not a reason to self-treat a suspected deficiency, because the serious form is a medical emergency.
Wernicke’s encephalopathy is caused by acute thiamine deficiency, most often in alcohol dependence or severe malnutrition. It classically presents with:
- Confusion.
- Unsteadiness on the feet (ataxia).
- Abnormal eye movements.
All three are present in only a minority of cases, so any one of them in someone at risk should prompt urgent action. It requires high-dose thiamine given by injection, because absorption from the gut cannot deliver enough quickly enough. Untreated, it can progress to Korsakoff syndrome — permanent, disabling memory damage — or death.
If someone with alcohol dependence or severe malnutrition becomes confused or unsteady, treat it as an emergency and get them to hospital. Do not manage it with tablets at home. A crucial practical point: giving glucose or a sugary drink to a thiamine-deficient person without thiamine can precipitate Wernicke’s, because glucose metabolism consumes the little thiamine remaining. Medical staff know this — it is a reason to get help rather than improvise.
Speak to a doctor or pharmacist before starting if you:
- Drink heavily, or are reducing your alcohol intake. Thiamine matters here and should be professionally managed.
- Have persistent nerve symptoms, which need diagnosis — B12 deficiency, diabetes and thyroid disease cause similar symptoms and are treated differently.
- Are being treated for severe malnutrition, where refeeding without thiamine can be dangerous.
- Are pregnant or breastfeeding.
- Have kidney disease or are on dialysis.
- Are giving it to a child.
- Already take a B-complex or multivitamin.
See a doctor rather than self-treating for persistent fatigue, tingling, numbness, weakness, unsteadiness or memory problems.
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Frequently asked questions
What is thiamine used for? Treating and preventing vitamin B1 deficiency — most importantly in alcohol dependence, and also in malnutrition, malabsorption, heart failure and persistent vomiting.
What are thiamine 100 mg tablets used for? A common single-vitamin strength, used to correct or prevent deficiency, frequently prescribed alongside alcohol reduction.
Is thiamine the same as vitamin B1? Yes. They are two names for the same nutrient.
Why is thiamine used for alcohol withdrawal? Alcohol impairs thiamine absorption, storage and use while often displacing food. Deficiency can cause Wernicke’s encephalopathy, which can lead to permanent memory damage.
Will thiamine give me more energy? Only if you are deficient. It helps release energy from food, but taking it when levels are normal does not create energy.
Can I take too much? Thiamine is water-soluble and excess is excreted, so oral toxicity is essentially not seen. It is among the safest vitamins to supplement.
Can thiamine help nerve pain? Where symptoms come from a thiamine deficiency, replacing it helps. Other causes need different treatment, so get symptoms assessed.
When is thiamine deficiency an emergency? Confusion, unsteadiness or abnormal eye movements in someone with alcohol dependence or malnutrition needs urgent hospital treatment with injected thiamine.