Acetaminophen may be doing more than just dulling pain in your brain it could be stopping it before it even starts. Scientists at Hebrew University have discovered that a metabolite of the drug, AM404, blocks pain signals right at their source by shutting down specific sodium channels in pain-sensing nerves. This radically shifts our understanding of how this common medication works and opens a door to new, more targeted painkillers that might eliminate side effects like numbness or weakness.