Do not use if you are allergic to aspirin. Children and teenagers should not use BC® for chicken pox or flu before consulting a doctor about Reye's syndrome, a rare but serious illness associated with aspirin. Pregnant women should not use BC® during the last 3 months of pregnancy unless directed by a doctor. If you consume 3 or more alcoholic drinks per day, consult your doctor before using BC®. Aspirin may cause stomach bleeding.