Thiamine (Vitamin B1)

How it works

As its active form thiamine pyrophosphate, it is an essential cofactor for enzymes of carbohydrate metabolism, and replacement restores normal cerebral and peripheral energy metabolism.

Prescribing in practice

• In suspected or established Wernicke's encephalopathy, give parenteral thiamine before or with any glucose, since administering carbohydrate first can precipitate or worsen the condition.
• Parenteral high-potency thiamine carries a small risk of anaphylaxis, so administer where facilities to manage this are available.
• Maintain a low threshold for treatment in alcohol-dependent and malnourished patients, as deficiency is frequently underdiagnosed.

Monitoring

Monitor the clinical response of neurological and other deficiency features, and observe for hypersensitivity reactions during parenteral administration.

Counselling the patient

• This vitamin replaces a deficiency that can affect the brain and nerves.
• Attending for treatment is important even if you feel relatively well.
• Report any rash or breathing difficulty during an injection.

Evidence & guidelines

Prompt thiamine replacement to prevent and treat Wernicke's encephalopathy is endorsed by NICE alcohol-use disorder guidance.