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Antibiotics

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By Editorial Team

2 min read

Reviewed by: HU Medical Review Board | Last reviewed: January 2025 | Last updated: January 2025

Many medicines are used to treat the symptoms of inflammatory bowel disease (IBD). The two main types of IBD are Crohn’s disease and ulcerative colitis (UC). Depending on the person’s condition and its location and severity, medicine may help improve symptoms or reach remission.1

Antibiotics are a group of drugs used to treat infections caused by bacteria. Doctors may prescribe antibiotics to people with IBD if they have developed an infection.2

How do antibiotics work for IBD?

People with IBD may develop infections that require treatment with antibiotics. For example, Clostridium difficile (C.difficile, or C.diff) is a bacteria that attacks the lining of the intestines and causes fever, pain, cramping, diarrhea, and bloody stools. People with IBD are especially vulnerable to to C.diff.1

Those with Crohn’s disease also may need antibiotics to treat pockets of pus (abscesses) or abnormal connections between the intestines and other body parts (fistulas). Antibiotics are also given to people with IBD after surgery to prevent infections.1

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Antibiotics may be needed in patients with UC in cases of toxic colitis.3

Examples of antibiotics for IBD

Antibiotics used to treat IBD may be given as a pill or an IV infusion. These drugs may be prescribed alone or in combination. They include:2,4

  • Metronidazole (Flagyl®)
  • Ciprofloxacin (Cipro®)
  • Vancomycin (Firvanq®)

What are the possible side effects?

Side effects can vary depending on the specific drug you are taking. Common side effects of antibiotics for IBD include:2,5-8

  • Nausea, vomiting, and cramping
  • Diarrhea
  • Loss of appetite
  • Abdominal pain
  • Headache
  • Rash
  • Abnormal liver tests

Ciprofloxacin has a black box warning, the strictest warning from the US Food and Drug Administration (FDA). It has this warning because people taking it have developed:6

  • Tendinitis and ruptured tendons
  • Nerve pain, tingling, and numbness in the hands and feet (peripheral neuropathy)
  • Central nervous system changes
  • Worse symptoms of myasthenia gravis

These are not all the possible side effects of antibiotics. Talk to your doctor about what to expect when taking antibiotics. You also should call your doctor if you have any changes that concern you when taking an antibiotic.

Other things to know

While antibiotics are an important tool to treat bacterial infections in people with IBD, it is important to avoid overuse. Some research shows that using antibiotics may increase the risk of developing IBD or C.diff.1,4

Some antibiotics are not safe to take during pregnancy or while breastfeeding. For example, metronidazole should not be taken in the first 3 months of (first trimester) of pregnancy. Before starting an antibiotic, tell your doctor if you are pregnant, breastfeeding, or planning to become pregnant or breastfeed.2,5-8

People who take certain blood thinners may need to change their dose when taking antibiotics.2

You should avoid drinking alcohol while taking metronidazole and for 2 days after stopping the drug.2,5

Your doctor should monitor your blood levels when you take vancomycin because it can cause kidney damage. Monitoring is especially important for people over age 65.8

Several medicines can interact badly with antibiotics. Before beginning treatment for Crohn’s disease or ulcerative colitis, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.5-8

Other drugs that may be prescribed for IBD include:1,3

  • Immunomodulators
  • Corticosteroids
  • Aminosalicylates (5-ASAs)