It's generally not advised to take Excedrin while breastfeeding. Here's why: Excedrin is a combination of acetaminophen1 , aspirin2 and caffeine, and research shows that these substances can get into breast milk and potentially affect your baby. For instance, a study in the Journal of Human Lactation points out that salicylates, like the aspirin in Excedrin, could lead to Reye's syndrome, a rare but serious condition in children.
Also, caffeine in moderate amounts is typically okay when breastfeeding, but higher amounts could make your baby fussy or interfere with their sleep. Acetaminophen, on the other hand, is usually safe in typical doses, but the combination with other substances in Excedrin makes it more complex.
Of course, it's always best to check with your healthcare provider for advice tailored to your situation.