Diarrhea caused by Shigella usually resolves without antibiotic treatment in 5 to 7 days. People with mild shigellosis may need only fluids and rest. Bismuth subsalicylate (e.g., Pepto-Bismol®) may be helpful but medications that cause the gut to slow down, such as loperamide (e.g., Imodium®) or diphenoxylate with atropine (e.g., Lomotil®), should be avoided 5. Antibiotics are useful for severe cases of shigellosis because they can reduce the duration of symptoms 6. However, Shigella is often resistant to antibiotics. If you require antibiotic treatment for shigellosis, your healthcare provider can culture your stool and determine which antibiotics are likely to work. Tell your healthcare provider if you do not get better within a couple of days after starting antibiotics. He or she can do additional tests to learn whether your strain of Shigella is resistant to the antibiotic you are taking.