(HealthDay News) -- Loperamide and bismuth subsalicylate are over-the-counter drugs designed to help people with diarrhea feel better.

The American Academy of Family Physicians says while they're safe for most people, not everyone should take these medicines. Among those who should avoid the drugs:

• Children aged 6 or younger should avoid loperamide; 12 or younger should avoid bismuth subsalicylate.
• Anyone with a fever, bloody or black stools, or prior allergic reaction to the drug should avoid loperamide.
• Anyone who has an allergy to aspirin or salicylate medications should avoid bismuth subsalicylate.
• Anyone aged 12 to 18 who could have the chickenpox or flu also should avoid bismuth subsalicylate.