There is insufficient research on digestive symptoms and outcomes following coronavirus disease (COVID-19) vaccination. We aimed to investigate digestive symptoms and related complications among South Koreans who were administered COVID-19 vaccines.

Forty-six patients (men: 22, women: 24) with a median age of 68 years (interquartile range:55.5, 73.8 years) who experienced digestive symptoms following COVID-19 vaccination between March 1 and July 30, 2021, were included. This retrospective single-center study collected information on clinical symptoms, laboratory tests, imaging results, comorbidities, complications, treatment type, and prognosis.

Thirty-three (71.7%), nine (19.6%), and three (6.5%) patients were administered AZD1222 (AstraZeneca), BNT162b2 (Pfizer/BioNTech), and JNJ-78436735 (Johnson and Johnson) vaccines, respectively. Patients were classified with mild (25 patients, 54.3%), moderate (five patients, 10.9%), and severe (16 patients, 34.8%) based on disease severity. Digestive symptoms included abdominal pain, diarrhea, dyspepsia, and nausea, which usually developed within 1 day (78.3%) following the first vaccination. In total, 14 (30.4%) patients experienced only gastrointestinal symptoms, whereas 32 (69.6%) experienced non-gastrointestinal symptoms. Complications included enterocolitis (76%), acute kidney injury (9%), anaphylactoid reaction (2%), and duodenal perforation (2%).

COVID-19 vaccines caused digestive symptoms and other complications that ranged from mild to severe. While further validation is required, our results suggest that monitoring digestive symptoms following COVID-19 vaccination can help detect rather severe complications that require medical intervention.