Background: Complementary and alternative medicines are widely used in Australia, including in rural communities, often alongside conventional care. Turmeric supplements are promoted for musculoskeletal and gastrointestinal health, yet recent case reports describe microscopic colitis temporally associated with turmeric containing products. Case: A 76 year old woman with uncomplicated diverticular disease was referred to a regional general surgery clinic with a two month history of constant bilateral lower abdominal cramping and severe non bloody diarrhoea. Stool culture was positive for Blastocystis species; given the controversial pathogenicity of this organism and only transient symptom improvement with antibiotics, this was considered an incidental finding. She had no recent travel, infectious contacts or other clear risk factors. Further history revealed commencement of a high dose turmeric supplement (15,800 mg daily with piperine) on the advice of a naturopath for arthritis shortly before symptom onset, markedly exceeding typical supplemental doses. She was advised to cease all turmeric products prior to colonoscopy. Her diarrhoea resolved completely and she remained asymptomatic off the supplement. Colonoscopy demonstrated normal macroscopic mucosa, but segmental colonic biopsies showed lymphocytic colitis without dysplasia or malignancy, consistent with drug associated microscopic colitis with a strong temporal relationship to turmeric exposure. Conclusion: This case adds to emerging evidence that high dose turmeric supplements may be associated with microscopic colitis, including lymphocytic colitis, in susceptible individuals. General surgeons should maintain suspicion for supplement related microscopic colitis in patients with new onset watery diarrhoea. A comprehensive medication history, including over the counter and herbal products, is essential, and cessation of suspected supplements may be both diagnostic and therapeutic.