Analgesics are among the oldest drugs described, albeit not necessarily for medicinaluse. Forexample,theSumeriansisolatedopioids(probablyfortheir euphoric effects) in the third millennium b. c. and the use of willow bark (salicin) for fever was ?rst reported in the eighteenth century. Both types of drugs are still in use, but today they are supplemented by a wide array of substances ranging from antidepressants to ion channel blockers. Not all of theseareprescribedbyphysicians. Manycompoundsaresoldoverthecounter and thus available to the public for self-medication. As a result, analgesics are also the most misused class of drugs and are the culprit for a multitude of healthproblemsdueto untoward sideeffects. Thisvolumeattemptstosummarizethecurrentstateofknowledgeonme- anisms underlying the various effects of these drugs, their side effect pro?les, and their indications and contraindications in clinical use.