Beriberi (thiamine deficiency)
The disease caused by a lack of vitamin B1 (thiamine). 'Dry' beriberi damages the nerves, causing weakness and tingling in the legs; 'wet' beriberi strains the heart, causing swelling and breathlessness. It is treatable — and rapidly reversible — with thiamine.
What it is
Beriberi is the classic disease of vitamin B1 (thiamine) deficiency. Thiamine is essential for turning carbohydrates into energy, so tissues with high energy demands — the nerves and the heart — are hit hardest when it is lacking. Historically it appeared in populations living on polished (white) rice; today, in developed countries, it is seen mainly with chronic heavy alcohol use (which impairs thiamine intake, absorption and use), and also with prolonged vomiting, severe malnutrition, bariatric surgery, or feeding a malnourished person without giving thiamine. It takes two main forms. 'Dry' beriberi is a nerve disease: a symmetrical peripheral neuropathy causing weakness, aching, numbness and tingling in the legs, with muscle wasting and difficulty walking. 'Wet' beriberi affects the heart and circulation, causing a fast heart, an enlarged straining heart, breathlessness and swelling of the legs (a form of high-output heart failure). A related, urgent brain form — Wernicke's encephalopathy — causes confusion, eye-movement problems and unsteadiness. Beriberi is important because it is both potentially serious and highly treatable: giving thiamine, usually by injection at first, can reverse it, sometimes dramatically.
Key lab markers
- Thiamine (vitamin B1) — a low level supports the diagnosis, though treatment is often started on clinical grounds before results return.
- Blood lactate — can be raised, reflecting impaired energy metabolism.
- A prompt response to thiamine — improvement after treatment is itself a strong clue.
- Assessment for alcohol use, nutrition and magnesium — magnesium is needed for thiamine to work and is often replaced alongside.
- Heart assessment (ECG, echocardiogram) — in wet beriberi.
Symptoms
- Weakness, aching, numbness and tingling in the legs (dry beriberi)
- Difficulty walking, muscle wasting
- Breathlessness, swollen legs, a fast heartbeat (wet beriberi)
- Tiredness
- Confusion, unsteadiness or eye-movement problems (Wernicke's — urgent)
- Often a background of heavy alcohol use, poor nutrition or prolonged vomiting
Related symptoms
When to discuss with a doctor
Beriberi should be suspected in anyone with unexplained leg weakness, tingling, or heart failure occurring alongside heavy alcohol use, severe malnutrition, prolonged vomiting or recent weight-loss surgery — and it needs prompt medical attention. It matters greatly because thiamine treatment is safe and can reverse the condition quickly, whereas delay risks permanent nerve or brain damage. Confusion, unsteadiness or abnormal eye movements in an at-risk person suggest Wernicke's encephalopathy, a medical emergency needing urgent thiamine. A crucial safety point: in a malnourished person, giving glucose (for example a sugary drink or IV fluids) before thiamine can precipitate or worsen the deficiency, so thiamine is given first. Mediora.AI can highlight a low thiamine and the associated pattern, but suspected beriberi — especially with heart or brain symptoms — needs prompt clinical care and thiamine replacement guided by a doctor.