A review of more than 65 studies that included 11,000 people with lower back pain has found that acetaminophen may be as effective as non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. Researchers say their findings support lower back pain guidelines that call for treatment with NSAIDs only after acetaminophen has been tried, because acetaminophen has fewer side effects than NSAIDs.