12/25/12 I has emergency surgery for septic small intestine removing 3 feet of small intestine that day and the next day a hemicolectomy was done . I have had a lot of trouble with diarrhea and gas with an embarrassing odor. My GI doctor told me to try to find simethicone and charcoal. ## Hi, Marcy! Sorry about the problem that you're having. Have you tried the Simethicone and charcoal, yet? Both are available over the counter in most drug or health stores. I am not aware of any single preparation the contains both, you'll most likely have to buy both separately, but they are very readily available. Learn more Simethicone details here. The Simethicone is an anti-gas substance, it's frequently the active ingredient in products, such as Gas-X, as well as many store brands and ...