Abstract
A healthy 49-year-old female developed intractable watery diarrhea after the Pfizer SARS-Cov2 mRNA vaccination. She was subsequently diagnosed with collagenous colitis (CC). She had no prior history of medication use, suggesting of vaccination being the trigger. CC or lymphocytic colitis should be considered as differential diagnoses for persistent watery diarrhea after SARS-Cov2 mRNA vaccination.