NSAIDs are among the most common pain relievers in the world. NSAIDs or nonsteroidal anti-inflammatory drugs are among the most common pain relief medicines in the world. Every day more than 30 million Americans use them to soothe headaches, sprains, arthritis symptoms, and other daily discomforts, according to the American Gastroenterological Association. And as if that wasn't enough, in addition to dulling pain NSAIDs also lower fever and reduce swelling. NSAIDs work on a chemical level. They block the effects of special enzymes specifically Cox-1 and Cox-2 enzymes. These enzymes play a key role in making prostaglandins. By blocking the Cox enzymes, NSAIDs stop your body from making as many prostaglandins. This means less swelling and less pain. A few different types of NSAIDs are available over the counter: Aspirin (Bayer, Bufferin, Excedrin); Ibuprofen (Advil, Motrin IB); Naproxen (Aleve). Opioid analgesics have been used as medicinal agents, especially for the treatment of acute and chronic pain. Morphine is the most commonly used opioid analgesic in the postoperative period, but some practitioners prefer other agents, such as hydromorphone. Opiate pain relievers are strong medicines that can be very helpful in treating pain, especially after an injury or surgery. They are safest when you use them exactly as your doctor prescribes. But there is a risk of addiction when you take them for more than a few days. Drugs like codeine, fentanyl, hydrocodone, hydrocodone/acetaminophen, meperidine are commonly used opioid analgesics for pain. Less common side effects include: Ulcers of the oesophagus, Heart failure, Hyperkalaemia, Reduced kidney function, Bronchospasm, Skin infections.