Bismuth Subsalicylate is the active ingredient in Pepto-Bismol and inhibits prostaglandin G/H Synthase 1/2. Target: Others Bismuth Subsalicylate reduces inflammation/irritation of stomach and intestinal lining through inhibition of prostaglandin G/H Synthase 1/2 [1]. Bismuth Subsalicylate is the active ingredient in Pepto-Bismol, an anti-diarrhea medication and antacid. In the gastrointestinal tract, Bismuth Subsalicylate is converted to salicylic acid and insoluble bismuth salts [2]. Bismuth subsalicylate treatment for 8 weeks is safe and well tolerated. This regimen appears to be efficacious for the treatment of microscopic colitis and is worthy of further study in a controlled trial [3].