Thiamine (Vitamin B₁)

Thiamine hydrochloride injection is used to rapidly restore vitamin B1 levels when deficiency is severe or oral intake isn't possible. Main conditions it treats include:

• Beriberi — both "dry" beriberi (affecting the nervous system) and "wet" beriberi (affecting the heart and circulation)
• Wernicke's encephalopathy / Wernicke-Korsakoff syndrome — a serious brain disorder caused by thiamine deficiency, often linked to alcohol use or poor nutrition
• Infantile beriberi — thiamine deficiency in infants, including cases with acute collapse
• Neuritis of pregnancy — nerve problems during pregnancy when vomiting prevents adequate oral intake
• Heart failure from thiamine deficiency — cardiovascular disease directly caused by low B1 levels
• Prevention of heart failure in patients receiving IV dextrose — used when patients with borderline thiamine levels are getting glucose through an IV
• Established thiamine deficiency with inability to eat — for patients who cannot take thiamine by mouth due to severe nausea, vomiting, anorexia, or malabsorption

Thiamine (vitamin B1) is essential for energy production. Once in the body, it combines with ATP (adenosine triphosphate, the body's main energy molecule) to form thiamine pyrophosphate — the active coenzyme form. This coenzyme is critical for breaking down carbohydrates, specifically for a step called decarboxylation of pyruvic acid and other alpha-keto acids. Without enough thiamine, pyruvic acid builds up in the blood — a key sign of B1 deficiency — and cells, especially in the brain and heart, can't generate energy properly.

Because the body needs more thiamine when carbohydrate intake is higher, people eating a high-carbohydrate diet or receiving IV dextrose are at greater risk of depleting their thiamine stores quickly. The body can become depleted after roughly three weeks without any thiamine intake.

Thiamine hydrochloride injection is given by a healthcare professional — either into a muscle (IM) or into a vein (IV), depending on the condition and its severity. Wet beriberi with heart failure is treated as a cardiac emergency and requires slow IV administration. For other forms of deficiency, IM injections are typically given multiple times a day for a period of weeks.

• IV administration must be done slowly and with caution — rapid IV infusion increases the risk of a severe reaction
• Once the acute phase improves, a doctor may switch to an oral multivitamin with thiamine taken daily for about a month to fully replenish body stores
• Correcting diet — eating a balanced, nutritious diet — is an important part of full recovery

Follow your prescriber's instructions carefully, and do not adjust the dose or schedule on your own.

Most people tolerate thiamine injections well, but some reactions can occur:

• Feeling of warmth after injection
• Itching (pruritus) or hives (urticaria)
• Sweating
• Nausea
• Weakness or restlessness
• Tightness of the throat
• Tenderness or a firm lump at the IM injection site

Rarely, a severe and potentially fatal allergic reaction (anaphylaxis) can occur — with symptoms like throat tightening, bluish skin (cyanosis), swelling, fluid in the lungs, or collapse. Get emergency help immediately if any of these develop after an injection.

• Anaphylaxis risk: Serious, life-threatening allergic reactions have been reported — including deaths — especially with repeated injections. Thiamine must always be administered where emergency treatment (epinephrine, oxygen, airway support) is immediately available.
• Allergy testing before injection: If you have a history of drug allergies or have reacted to thiamine before, a small test dose should be given under the skin first and watched for 30 minutes before a full dose is given. Even a negative skin test does not fully rule out a reaction.
• Aluminum toxicity: This product contains aluminum. In patients with kidney problems — especially premature newborns — aluminum can accumulate and cause toxicity affecting the brain and bones.
• Wet beriberi emergency: If beriberi has caused heart failure, this is a cardiac emergency. IV thiamine must be given very slowly and under close medical supervision.

The FDA label for this product does not list specific drug, food, or supplement interactions.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Allergy to thiamine: Do not use this product if you have a known allergy to thiamine or any ingredient in the formulation.
• Kidney problems: Tell your care team if you have impaired kidney function — aluminum in this product can build up and become toxic when the kidneys can't clear it properly.
• Premature newborns: This population is at especially high risk for aluminum toxicity because their kidneys are not yet mature.
• History of drug allergies: Let your doctor know if you've had allergic reactions to medications before — a skin test should be performed first.
• Pregnancy with severe vomiting: If you're pregnant and can't keep food or oral vitamins down, talk to your doctor — injection may be appropriate but requires medical oversight.

Single parenteral (injected) doses given in research have not caused toxic effects. However, the body can only use a limited amount of thiamine at a time — once tissues are saturated, the rest is excreted in the urine. If intake is pushed even higher, thiamine appears unchanged in the urine, meaning the excess simply passes out of the body.

Thiamine is essential for carbohydrate metabolism — specifically, it helps break down pyruvic acid and alpha-keto acids in the blood. When thiamine is deficient, pyruvic acid builds up, which can be measured in the blood as a marker of deficiency. The heart and nervous system are particularly sensitive to this buildup, which is why deficiency causes both neurological and cardiovascular problems. Restoring thiamine reverses these metabolic disruptions.

Thiamine is a water-soluble vitamin absorbed throughout the body, with the highest concentrations found in the liver, brain, kidneys, and heart. After an IM injection, absorption is rapid and complete. The body stores thiamine up to two to three times normal levels when intake is plentiful, but stores become depleted if intake is insufficient — full depletion can occur in about three weeks without any thiamine. Because it's water-soluble, any excess thiamine is quickly excreted in the urine, first as a breakdown product called pyrimidine and then as unchanged thiamine as levels rise further.

Store at 20° to 25°C (68° to 77° F) . PROTECT FROM LIGHT.