Thiamine (Injection, Oral)

Thiamine is a vitamin that is essential to the proper operation of the human body.


Thiamine is known as vitamin B1, and if a person does not get enough of this essential nutrient that they are unable to make themselves, then there can be complications that lead to various disorders and can even prove fatal in extreme cases. For that reason, it was isolated and then created (in 1926 and 1936 respectively) so that it could be given through either the oral route or an injection. It has proven so important that it has been placed on the World Health Organization's (WHO) Model List of Essential Medicines under the Vitamins and Minerals subcategory.

Thiamine has its place in the class of B vitamins that are water-soluble and they have a significant role in cell metabolism. It can often be found in various types of foods as Vitamin B1, but if a person is unable to garner enough through this, then they will have to use the oral tablet that is marketed under the brand name Thiamilate or else receive an injection of the Vitamin B-1 solution. It is quite an affordable nutritional supplement that can often be purchased in the United States for less than $25 per month.

In most cases, a healthy diet will provide enough thiamine for a person to exist on, but there are some who cannot gather enough through eating. Also, there's a number of health conditions that can cause a deficiency of the nutrient due to the way that they interfere with the normal body functions. Such conditions include some stomach and intestinal problems, alcoholism, or cirrhosis of the liver. Dialysis and high doses of diuretics can also lead to the beriberi (thiamine deficiency), and there is also a genetic condition that can sometimes occur and cause those afflicted to have a problem absorbing the thiamine that they receive through their diet. Without the necessary amount, people are apt to develop serious problems such as heart failure or mental/nerve problems.

Those who do not respond well enough to the oral form are usually given an injection that will help them to absorb the nutrient better, or this might be the chosen option just because it is likely to work better in this regard. For the most part, this type of deficiency is infrequent in developed countries such as the United States, but it does stay pretty common in other areas such as sub-Saharan Africa. For that reason, the wholesale cost has continued to be improved so that now that the latest data has a one gram vial being available for $2.17, and that makes it affordable for many who might need thiamine supplementation. In many of these cases, thiamine is a valuable resource since its supplementation is able to resolve most symptoms within the course of a few weeks once a regimen has begun.

It is recommended that men receive a slightly higher amount of thiamine daily than women, with the United States Institute of Medicine publishing the Estimated Average Requirements (EARs) specifying 1.0mg/day for men and 0.9mg/day for women. There are a number of foods that are naturally rich in this nutrient with pork, spinach, and cornflour being some of the most recognized. It can also be received from a number of processed and whole foods with items like rice, edible seeds, and breakfast cereals being some of those higher on the list. However, as mentioned, the oral and injection supplements exist to ensure that people are able to stay above the threshold so that they do not experience complications.

Treated Conditions

  • Thiamine deficiency
  • Optic Neuropathy
  • Beriberi
  • Wernicke-Korsakoff syndrome
  • Maple syrup urine disease
  • Leigh's disease

Type of Medicine

  • Thiamilate tablet
  • Vitamin B-1 solution for injection

Side Effects

Thiamine, as with most vitamins of the B-complex, generally does not cause many side effects, with those that do occur usually being quite mild. These mild side effects that might manifest include nausea, tightness in the throat, restlessness, or sweating with a warm feeling throughout the body. The injection form has the possibility of a mild rash with itching at or near the injection site with a tenderness or hard lump at the site also seen in some. The most serious of the side effects, though rare, is an allergic reaction that will require immediate medical attention. Some of the side effects seen during an allergic reaction include bluish lips, chest pain with shortness of breath, black/bloody stools, or a bloody cough or vomit that looks like coffee grounds. If any of these occur, then a person may be experiencing anaphylaxis that is a serious allergic reaction that has led to death in some instances.


In the oral formulation, this vitamin is taken with or without food either once or up to 3 times per day. The daily recommended intake varies depending on the country as well as on the individual. In the US, adult and teenage males are usually directed to take 1.2 to 1.5 milligrams (mg) per day with adult and teenage females given slightly less at 1 to 1.1 mg per day. However, pregnant or breastfeeding females or children will have different specifications as well.

The vitamin B-1 solution is injected into a vein or muscle as directed depending on the condition and response. In these cases, the thiamine supplement is generally given intravenously initially, and then this can be reduced some and converted to the oral form for the remainder of the term. It is important not to exceed these recommended levels.

Drug Interactions

As thiamine is naturally found in the diet, there are no known interactions with other drugs. However, there are some known antagonists that can degrade it in a number of ways, and this might also be a concern if someone taking the supplement is ingesting a plethora of these compounds. For example, sulfites might often be used as a food preservative, and it will attack the methylene bridge in a way that splits apart the thiazole ring from the pyrimidine ring. Likewise, thiaminases are a class of enzymes that can break down vitamin B-1 into a couple different parts, and that is where they get their eponymous name. These thiaminases might be found in various forms of raw fish, shellfish, some bacteria strains, and plants such as Bracken. Because of the fact that Rumen bacteria can work to reduce sulfate to sulfite, thiamine-antagonistic activities are likely to result if someone is taking in a diet with a large amount of sulfate. A list of further thiamine antagonists includes quercetin, rutin, chlorogenic acid, tannic acid, and caffeic acid. Diets that include large levels of any of these aforementioned antagonists should be altered in order to accommodate for the body that is lacking in thiamine efficiency.


Anyone who has a thiamine allergy should discuss this with the health professional before utilizing a supplement version. There can also be some inactive ingredients that might lead to an allergic reaction, and so it is important to reveal any other allergies with the physician before taking it. The solution formulation that is used for an injection can contain aluminium that has been known, in rare instances, to build up within the body to dangerous levels. The likelihood of this occurring will increase if a person utilizes the thiamine for an extended period or if they already have a renal issue such as kidney disease.

There are quite a few conditions that can inhibit the body's ability to absorb enough thiamine as needed, and these include the following:

  • Overactive thyroid
  • Stress
  • Surgical removal of stomach
  • Illness
  • Intestinal disease
  • Liver disease
  • Alcoholism
  • Burns
  • Diarrhea
  • Fever

If any of these are relevant, then the thiamine level should be carefully monitored in order to determine whether or not there is a need for an additional means of uptake. The side effects that are seen with this nutrient are generally negligible, but there are some rare cases of severe allergic reactions and these should be handled swiftly if they do manifest.


As with most things, thiamine should be stored at room temperature in containers that are tight and secure enough to avoid light, heat, and moisture contamination. Thiamine is unstable and will deteriorate when exposed to heat, but it is able to remain stable when frozen in case such a storage protocol is necessary.


Thiamine, also known as vitamin B-1, has an extensive history that started with it being the first of the water-soluble vitamins to be discovered. It was then found that it was one of the trace compounds that humans and other animals need in order to survive, and so vitamins were discovered. The deficiency of this vitamin might lead to various disorders and problems such as the Beriberi condition that stumped the Japanese navy and others for quite some time before being linked to a diet that consisted of solely white rice and a lack of thiamine. One of the most prolific vitamin deficiency syndromes that still occurs in the modern world is the Wernicke's disease that is most closely linked to malnutrition, chronic disorders, and chronic alcohol abuse. Infants might also encounter this deficiency due to a mother breastfeeding them while suffering from the deficiency themselves. Also, soybean and other formulas that are often used with infants can have the thiamine deactivated through the heat treatment process, and so this needs to be avoided in many as well. There is also an increased level in some people such as diabetic patients who need dialysis, those with short bowel syndrome, or patients undergoing chemotherapy. In these people, it might manifest as Wernicke's disease that can mostly have its symptoms reversed if the proper supplementation regimen is given before it is too late to overcome some of the harsh effects of the illness.

Nowadays, there are oral tablets and injectable solutions that can help to compensate for lower levels in people around the globe. The Thiamilate brand name is one of the most popular in the United States when given by a doctor.

There is also a number of vitamin B-1 analogues in existence that can help to restore thiamine in the body due to their increased bioavailability in relation to the vitamin by itself. In order to achieve a feasible level of heart and nerve health, it is most often given along with directions for a coordinated diet that will help to normalize the thiamine levels within a person. Thiamilate is a brand name found in the United States for the tablet version, and there are more generic over-the-counter variations that can be found in either the B-1 vitamin isolated or in the super B-complex. Thiamine Hcl, or the vitamin B-1 solution is the alternative form that can be injected into a vein or muscle as needed.

Last Reviewed:
December 23, 2017
Last Updated:
April 05, 2018
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