Treat on suspicion, do not wait for the full triad. Give parenteral thiamine before any glucose in at-risk patients. Untreated or under-treated Wernicke progresses to irreversible Korsakoff syndrome.
Triad (all three present in a minority)
- Confusion or acute encephalopathy
- Ataxia (wide-based gait)
- Ophthalmoplegia or nystagmus
At risk
- Alcohol dependence
- Hyperemesis gravidarum, eating disorders, prolonged vomiting
- Bariatric surgery, malabsorption, malignancy, prolonged starvation or parenteral nutrition
At risk
- Alcohol dependence, poor nutrition
- Give thiamine before any glucose
- Hyperemesis, bariatric surgery
Suspected Wernicke
- Confusion, ataxia or eye signs (any one)
- IV Pabrinex (high-dose thiamine)
- Treat even if the triad is incomplete
Untreated / Korsakoff
- Irreversible memory impairment
- Continue thiamine
- Prevent recurrence
Treatment
1
1. Thiamine (treatment dose)
IV Pabrinex, higher-dose, two or three pairs three times daily for several days when encephalopathy is suspected (follow local dosing), given before glucose.
IV Pabrinex, higher-dose, two or three pairs three times daily for several days when encephalopathy is suspected (follow local dosing), given before glucose.
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2
2. Treat the cause
Manage alcohol withdrawal, treat vomiting, restore nutrition, and correct magnesium (thiamine needs it to work).
Manage alcohol withdrawal, treat vomiting, restore nutrition, and correct magnesium (thiamine needs it to work).
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3
3. Monitor and prevent Korsakoff
Ophthalmoplegia improves fastest; confusion and ataxia more slowly. Continue treatment until no further improvement.
Ophthalmoplegia improves fastest; confusion and ataxia more slowly. Continue treatment until no further improvement.
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4
4. Continue oral thiamine
Step down to oral thiamine after the parenteral course and address ongoing risk factors.
Step down to oral thiamine after the parenteral course and address ongoing risk factors.
Remember
- Magnesium deficiency impairs thiamine use: replace it
- Prophylactic (lower) dosing for at-risk patients not yet encephalopathic
- Anaphylaxis to IV Pabrinex is rare: have resuscitation facilities
Pitfalls
- Waiting for the full triad before treating
- Giving glucose before thiamine
- Under-dosing (oral thiamine is not enough for acute Wernicke)
- Forgetting magnesium
MedPrep - www.medprep.uk - Educational revision aid only. Not clinical guidance. Doses are adult examples; check the BNF, current guidelines and local policy, and seek senior advice. Nov 2026