[3][4] In general, microscopic colitis causes chronic watery diarrhea with increased stool frequency.

Some patients report nocturnal diarrhea, abdominal pain, bowel urgency, fecal incontinence, fatigue and weight loss.

Use of nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors (PPIs) and beta blockers also appear to increase the risk of collagenous colitis, but the cause of this is not known.

[6] First line treatment for collagenous colitis is the use of budesonide, a steroid that works locally in the colon and is highly cleared by first pass effect.

Other medications that can be used include the following:[1][6] Pilot-scale studies have shown some evidence of possible benefit for both Boswellia serrata extract and specific strains of probiotics in the treatment of collagenous colitis, although larger sample sizes are needed to confirm the results.

Unlike in the previous study on data from 1995–1999, the rate of collagenous colitis in Olmsted County was found to have remained stable between 2011 and 2019.

The authors suggest an increase in the use of colonoscopies as a possible cause of the observed change in microscopic colitis diagnoses over time.