Diarrhea when taking antibiotics: what to know

Antibiotics affect bacteria causing an infection and can also disturb the normal balance of organisms in the bowel. This may lead to loose stools during treatment or shortly afterwards. Sometimes a different infection develops after antibiotic exposure, especially when diarrhea is frequent, watery, painful or accompanied by fever. The original illness also matters: antibiotics may be used for conditions such as cellulitis, chlamydia or Helicobacter Pylori Infection, but the new bowel symptoms still deserve separate review.

Drink regularly and use oral rehydration fluid if stools are frequent. Take the antibiotic exactly as prescribed until a prescriber tells you otherwise; do not share leftover tablets or start another course. Contact the prescriber to report the diarrhea, especially if it began soon after treatment or is worsening. Avoid anti-diarrhea medicine until a clinician advises it when fever, blood or significant pain is present.

Seek urgent care for blood or black stool, severe belly pain, repeated vomiting, faintness, confusion, very little urine or signs of an allergic reaction such as facial swelling or breathing difficulty. Contact a clinician promptly for persistent watery diarrhea, fever, or symptoms that continue after the course ends. Extra caution is needed for infants, older adults and people with weakened immunity.

Could the antibiotic be causing this, or do I need testing? Should my treatment be changed? Which fluids and medicines are safe with my other prescriptions? What warning signs should prompt same-day care?