Antibiotic-induced diarrhoea

A course of antibiotics may disturb the balance of microbes in the intestine, changing digestion and stool consistency. Mild looseness can settle, but profuse watery stools or bowel inflammation may have a different significance. Clostridioides difficile is one possible cause after antibiotic use and needs specific assessment. Food poisoning, a viral infection and the illness being treated can also cause diarrhoea, so timing is useful but not diagnostic.

Take frequent drinks and use correctly mixed oral rehydration solution when fluid losses are difficult to replace with usual drinks. Keep a note of stool frequency, blood or mucus, pain, fever and urine output. Speak with the prescribing service before omitting doses because an unfinished course may leave the original infection undertreated. Avoid sharing antibiotics and do not use leftover tablets to treat the diarrhoea.

Arrange urgent assessment if stools contain blood, abdominal pain is severe, the abdomen becomes distended, fever develops, or watery diarrhoea is frequent or worsening. Seek emergency help for fainting, confusion, extreme weakness, minimal urine, inability to drink or repeated vomiting. Infants, frail adults and people with significant immune suppression can deteriorate quickly and should receive early clinical advice.

Explain when diarrhoea began in relation to every recent antibiotic and whether anyone around you is unwell. Ask if the current prescription should be continued, changed or stopped, and whether a stool sample is needed. Confirm which pain relief or anti-diarrhoeal products are safe, since medicines that slow the bowel may be unsuitable when infection or inflammation is suspected.