Antibiotics for dysentery: when they are used

Dysentery describes diarrhoea containing visible blood, often with cramps and an urgent need to pass stool. Bacteria and parasites can both cause it, so self-treating with leftover antibiotics can be ineffective or harmful.

A clinician considers recent travel, unsafe food or water, contact with another ill person, medicines and immune health. A stool sample may identify a bacterium or parasite and help guide treatment. Amoebic dysentery requires specific antiparasitic medicines rather than a standard antibacterial drug.

Some bacterial infections improve with supportive care, while others warrant targeted antibiotics. Certain causes of bloody diarrhoea may become more dangerous with antibiotics, which is why assessment should come before treatment whenever possible.

Contact a clinician promptly and drink small, frequent amounts of oral rehydration fluid. Continue light food as tolerated. Do not use an anti-diarrhoeal medicine that slows the bowel when stool is bloody or fever is present unless a clinician specifically recommends it.

Wash hands thoroughly with soap and water after using the toilet and before handling food. Avoid preparing meals for others, swimming and sharing towels while diarrhoea continues. If an antimicrobial is prescribed, follow its directions and do not save remaining doses for another illness.

Seek urgent care for fainting, confusion, severe or worsening abdominal pain, repeated vomiting, inability to keep fluids down, very little urine, marked weakness, a swollen abdomen, or substantial bleeding. Babies, older adults, pregnant people and anyone with reduced immunity need a lower threshold for prompt assessment because dehydration and invasive infection can progress quickly.

Ask whether a stool test is needed, which rehydration fluid to use, whether any current medicine should be paused, what result would change treatment, and when it is safe to return to work, school or food preparation.