Naproxen is a non-steroidal anti-inflammatory drug (NSAID). Like other drugs in its class, it reduces pain by blocking cyclooxygenase, which in turn lowers prostaglandin levels. Prostaglandins are pain mediators. Local anesthetics like lidocaine deaden peripheral nerve activity by blocking voltage-gated sodium channels. Opioids like morphine stimulate opioid receptors. Substance P also participates in pain processing, but no approved drugs work by this mechanism.