A vitamin deficiency disease, caused by a lack of vitamin B1 (thiamine).

Early symptoms include fatigue, irritability, restlessness, loss of appetite, and abdominal discomfort.

As the disease progresses, patients develop burning sensations, tingling in the extremities, and numbness. Patients may develop psychosis or heart failure.

This disease does not only occur in India. Beriberi is most common in breast-fed infants whose mothers have inadequate thiamine intake, or among people whose diets include certain types of fish that produce an enzyme which inactivates thiamine.