Thiamine: Health benefits & Side effects

PIcture of Thiamine Vitamin B1


What is Thiamine (Vitamin B1)?

Vitamin B1, also called thiamine, is a B complex vitamin. It is found in many foods and is vitally important to keeping a body operating properly.

“Thiamine is involved in many body functions including the nervous system, heart and muscles,” said Dr. Sherry Ross, gynecologist and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, California. “It is also important in the flow of electrolytes in and out of nerve and muscle cells, enzymatic processes and carbohydrate metabolism.”

According to the University of Maryland Medical Center (UMM), thiamine was named B1 because it was the first B complex vitamin to be discovered. According to the Mayo Clinic, it was also one of the first vitamins of any kind ever be classified.

Thiamine Vitamin B1 Side Effects

Thiamine is LIKELY SAFE when taken by mouth in appropriate amounts, although rare allergic reactions and skin irritation have occurred. It is also LIKELY SAFE when given appropriately intravenously (by IV) by a healthcare provider. Thiamine shots are an FDA-approved prescription product.

Thiamine might not properly enter the body in some people who have liver problems, drink a lot of alcohol, or have other conditions.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Thiamine is LIKELY SAFE for pregnant or breast-feeding women when taken in the recommended amount of 1.4 mg daily. Not enough is known about the safety of using larger amounts during pregnancy or breast-feeding.

Important information about thiamine (Vitamin B1)

You should not use thiamine if you have ever had an allergic reaction to it.

Ask a doctor or pharmacist before taking thiamine if you have any medical conditions, if you take other medications or herbal products, or if you are allergic to any drugs or foods.

Before you receive injectable thiamine, tell your doctor if you have kidney disease.

Thiamine is only part of a complete program of treatment that may also include a special diet. It is very important to follow the diet plan created for you by your doctor or nutrition counselor. You should become very familiar with the list of foods you should eat or avoid to help control your condition.

Health benefits of thiamine

Thiamine is used to treat people who have heart disease, metabolic disorders, aging, canker sores, cataracts, glaucoma and motion sickness. There are many studies that seem to back up some of these uses. For example, research published by the Vietnamese American Medical Research Foundation found thiamine might improve the cognitive function of patients with Alzheimer’s disease. This vitamin is important for a wide range of brain functions and ailments in others, as well.

According to the UMM, thiamine is sometimes called an “anti-stress” vitamin. Research has found that B1 may strengthen the immune system and improve the body’s ability to control mood and physiological impairments due to stress.

“Thiamine is also used for maintaining a positive mental attitude, preventing memory loss, enhancing learning abilities, fighting stress and increasing energy,” Ross told Live Science. Thiamine injections are also given to patients who have a memory disorder called Wernicke’s encephalopathy, Ross added.

B1 may also be good for treating other impairments. According to the Milton S. Hershey Medical Center, many studies have also concluded that B1, along with other vitamins, may prevent cataracts. A study by the Laboratory of Pharmacotherapy at the Osaka University of Pharmaceutical Sciences in Takatsuki, Japan found that thiamine has a potential to prevent obesity and metabolic disorders in rats. Other researchers believe that vitamin B plays a part in the body’s metabolism and may be interregnal to the treatment of metabolic disorders.

Thiamine Vitamin B1 Dosage

The following doses have been studied in scientific research:


  • For adults with somewhat low levels of thiamine in their body (mild thiamine deficiency): the usual dose of thiamine is 5-30 mg daily in either a single dose or divided doses for one month. The typical dose for severe deficiency can be up to 300 mg per day.
  • For reducing the risk of getting cataracts: a daily dietary intake of approximately 10 mg of thiamine.

As a dietary supplement in adults, 1-2 mg of thiamine per day is commonly used. The daily recommended dietary allowances (RDAs) of thiamine are: Infants 0-6 months, 0.2 mg; infants 7-12 months, 0.3 mg; children 1-3 years, 0.5 mg; children 4-8 years, 0.6 mg; boys 9-13 years, 0.9 mg; men 14 years and older, 1.2 mg; girls 9-13 years, 0.9 mg; women 14-18 years, 1 mg; women over 18 years, 1.1 mg; pregnant women, 1.4 mg; and breast-feeding women, 1.5 mg.


  • Healthcare providers give thiamine shots for treating and preventing symptoms of alcohol withdrawal (Wernicke-Korsakoff syndrome).

Symptoms of vitamin B1 deficiency

The symptoms of B1 deficiency are many and typically are related to the nervous, muscular and gastrointestinal systems. According to a review published by the journal Congestive Heart Failure, symptoms include depression, emotional instability, uncooperative behavior, fearfulness, agitation, weakness, dizziness, insomnia, memory loss, pain sensitivity, peripheral neuropathy, sonophobia, backache, muscular atrophy, myalgia, nausea, vomiting and constipation.