Antibiotics in Crohn's disease and ulcerative colitis

• antibacterials, such as metronidazole and ciprofloxacin, may be prescribed in the treatment of fistulating Crohn's Disease to treat accompanying abscesses or in perianal Crohn's Disease or sepsis (1)
• antibiotics, including metronidazole, are indicated in
  • the treatment of symptoms attributable bacterial overgrowth
  • septic complications
  • perineal disease (3)
• significant side-effects of metronidazole include peripheral neuropathy if used long term (over three months), a bad taste in the mouth and a disulfiram-like interaction with alcohol
  
  
• antibiotics such as ciprofloxacin have also been used in the place of steroids to treat moderate relapses of ulcerative colitis

NICE suggest (4):

• to maintain remission in people with ileocolonic Crohn's disease who have had complete macroscopic resection within the last 3 months, consider azathioprine in combination with up to 3 months' postoperative metronidazole

Reference:

• (1) Prescriber (2004); 15(5).
• (2) Prescribers' Journal (1997);37(4): 232-42
• (3) Dignass A et al. The second European evidence-based consensus on the diagnosis and management of Crohn's disease: Current management. Journal of Crohn's and Colitis 2010; 4:28-62
• (4) NICE (May 2019). Crohn's disease: management