A previously well adult develops the passage of 5 loose watery stools per day for 2 days after a meal out. He has no blood in the stool and no high fever. What is the single most important principle of his management?

Answer: E. Fluid and electrolyte replacement, mainly with oral rehydration solution

Rehydration is the cornerstone

Acute diarrhoea (>=3 loose/watery stools per day, lasting under 14 days) is usually infective and self-limiting. Most deaths and complications are not from the infection itself but from inadequate fluid and electrolyte replacement, so rehydration - primarily with oral rehydration solution (ORS) - is the most important principle.

Why ORS works

• ORS uses sodium-glucose co-transport (SGLT1) in the small intestine: glucose drives sodium (and therefore water) absorption even when secretion is occurring.
• It is effective, cheap and life-saving in watery diarrhoea.

General management

1. Assess hydration and identify high-risk groups.
2. Rehydrate (ORS; IV fluids if severe).
3. Early re-feeding - continue breastfeeding/age-appropriate diet; avoid unnecessary food restriction.
4. Use antibiotics selectively.

Why not the others

Most acute diarrhoea does not need antibiotics; antimotility drugs are at most adjuncts (and avoided in dysentery); colonoscopy is not indicated acutely; prolonged fasting is harmful.