Ibuprofen is often a preferred pain medication because it is fast acting, while aspirin is favored for its anti-blood-clotting properties, according to the Harvard Medical School Family Health Guide. Both ibuprofen and aspirin are categorized as nonsteroidal anti-inflammatory drugs, or NSAIDs, a major categorization of over-the-counter pain medications.
Ibuprofen and aspirin both work by blocking enzymes that signal pain, reducing the sensation of pain. Aside from being fast acting, ibuprofen is favored because it does not remain long in the body, reducing the chance of stomach and kidney problems, according to the Family Health Guide.
Aspirin is most often used in small daily doses as protection against cardiovascular problems. Daily aspirin intake reduces the chance of blood clotting in arteries that supply blood to critical organs. Ibuprofen may be taken with aspirin, notes the Family Health Guide, but the FDA recommends waiting 30 minutes after taking aspirin to take ibuprofen as ibuprofen can block the intended anti-clotting effect.
Aspirin is not a safe pain medication for children as its use has been linked to Reye's syndrome, according to WebMD. Ibuprofen is safe for children 6 months and older at the right dosage. Consult the child's doctor for appropriate dosage before giving a child any over-the-counter pain medication.