Clinical bottom line
Acute radiation-induced enteritis (ARIE) is a common complication of abdominal or pelvic radiotherapy, characterized by inflammation of the small bowel mucosa leading to symptoms such as diarrhea, abdominal pain, and malabsorption. Recent advances emphasize early nutritional support, symptom-directed pharmacotherapy, and emerging regenerative therapies such as autologous bone marrow stromal cell transplantation. While supportive care remains the cornerstone, novel interventions targeting mucosal healing and inflammation modulation show promise but require further validation. Clinicians should maintain a high index of suspicion for ARIE in patients undergoing radiotherapy and tailor management to symptom severity and risk factors.
What the evidence shows
Radiation-induced enteritis results from radiation damage to rapidly dividing intestinal epithelial cells, causing mucosal barrier disruption, inflammation, and subsequent clinical symptoms (Bashir et al., 2012; Kumar Nagi et al., 2012). Acute enteritis typically manifests during or shortly after radiotherapy, with symptoms including diarrhea, cramping, nausea, and weight loss (Sourati et al., 2017). Imaging and endoscopy may reveal mucosal edema, erythema, and ulceration (Hartung et al., 2022).
Nutritional management is critical, as radiation enteritis can impair nutrient absorption and exacerbate malnutrition. Kumar Nagi et al. (2012) highlight the importance of tailored nutritional interventions, including enteral feeding when feasible, to support mucosal repair and maintain patient strength.
Pharmacologic treatments focus on symptom control and inflammation reduction. Antidiarrheals, analgesics, and anti-inflammatory agents are commonly used, though evidence for specific agents remains limited (Orangio et al., 2020). Fahmy et al. (2026) discuss parallels with radiation-induced proctitis, underscoring the potential role of topical anti-inflammatory therapies, though their efficacy in small bowel enteritis is less established.
A notable recent advance is the exploration of autologous bone marrow stromal cell transplantation as a regenerative therapy. Xu et al. (2016) demonstrated in a canine model that transplantation of these cells after moderate-dose radiation exposure improved mucosal healing and reduced inflammation, suggesting a potential future therapeutic avenue for ARIE.
Caveats and uncertainty
Despite advances, management of ARIE remains largely supportive, with a paucity of high-quality randomized controlled trials guiding specific pharmacologic or regenerative therapies. Most clinical recommendations derive from observational studies, expert opinion, or extrapolation from related conditions such as radiation proctitis (Fahmy et al., 2026).
The regenerative potential of bone marrow stromal cell therapy is promising but currently limited to preclinical data (Xu et al., 2016). Human trials are necessary to establish safety, dosing, and efficacy before routine clinical application.
Additionally, variability in radiation dose, field, and patient comorbidities complicates risk stratification and individualized treatment planning. The natural history of ARIE can vary from mild, self-limited symptoms to severe complications such as small bowel obstruction (Hartung et al., 2022), requiring vigilance and multidisciplinary management.
How this may change practice
Clinicians should prioritize early recognition of ARIE symptoms during radiotherapy and implement proactive nutritional support to mitigate malnutrition-related morbidity. Symptom-directed pharmacotherapy remains essential, with ongoing assessment to escalate care if complications arise.
Emerging regenerative therapies, particularly autologous bone marrow stromal cell transplantation, represent a potential paradigm shift toward mucosal healing rather than solely symptom control. While not yet standard of care, awareness of these developments may encourage enrollment in clinical trials and multidisciplinary collaboration.
Future practice may integrate biomarker-driven risk stratification and personalized treatment algorithms combining nutritional, pharmacologic, and cellular therapies to improve outcomes in ARIE.