Probiotics are microorganisms with potential health benefits. They may be used to prevent and treat antibiotic-associated diarrhea and acute infectious diarrhea. They may also be effective in relieving symptoms of irritable bowel syndrome, and in treating atopic dermatitis in children. Species commonly used include Lactobacillus sp., Bifidobacterium sp., Streptococcus thermophilus, and Saccharomyces boulardii. Typical dosages vary based on the product, but common dosages range from 5 to 10 billion colony-forming units per day for children, and from 10 to 20 billion colony-forming units per day for adults. Significant adverse effects are rare, and there are no known interactions with medications.