Gastrointestinal Infection
Gastrointestinal infection is inflammation of the stomach or intestines caused by a virus, bacterium or parasite. Diarrhoea, vomiting and cramps are common; the immediate concern is often dehydration rather than choosing an antimicrobial.
Key points
- Most short-lived watery diarrhoea does not benefit from antibiotics, and unnecessary use can cause harm.
- Oral rehydration replaces water and salts lost through diarrhoea or vomiting.
- Blood in stool, severe pain, high fever or symptoms in a vulnerable person should prompt medical assessment.
Antibiotic listings do not identify the organism or show that treatment is needed; travel, exposures, severity and test results guide that decision.
What matters during assessment?
Duration, stool appearance, fever, recent antibiotics, travel, unsafe food or water and immune status help narrow the cause. Stool testing is more likely when illness is severe, prolonged, bloody, recurrent or linked to an outbreak.
When are antimicrobials considered?
Antibiotics are reserved for selected bacterial infections; some causes of bloody diarrhoea can worsen with inappropriate treatment. Ciprofloxacin is active against some bacteria but resistance, interactions and adverse effects affect its use. Parasites require different medicines. See antibiotics for class information.
When to seek urgent care
Seek urgent help for inability to keep fluids down, very little urine, marked drowsiness, fainting, blood or black stool, severe or localised abdominal pain, a rigid abdomen, or high fever with worsening illness. Infants, frail older adults and immunocompromised people need earlier review.