When your body suffers an injury, a special type of nerve receptors in your skin send messages to the brain. Painkillers, as the name suggests, are types of medicines that help you treat and alleviate physical pain. What they do is actually not treat the injury but rather interfere with the enzymes and proteins that cause the perception of pain. They come in various forms and sizes, and can be taken by mouth in liquid, tablet or capsule form, by injection, or via the rectum (also known as back passage). Some painkillers are also available as creams or ointment.
In general, there are three main types of painkillers, according to their mechanism of work. Some of them, such as aspirin and opiates are based on naturally occurring drugs, while others are synthesized artificially.
The non-steroidal anti-inflammatory drugs, or NSAIDS, work by inhibiting the action of enzymes, known as cyclooxygenase enzymes. The latter are associated with the production of other chemicals, which in turn are involved in the production of pain and inflammation at the site of the injury. By blocking the action of these enzymes, the NSAIDS reduce the feeling of pain. NSAIDS drugs include aspirin (based on a chemical found in the willow bark), ibuprofen and naproxen. They’re also very effective in reducing the swelling or inflammation, and reduce the pain caused by arthritis and sore throat.
Paracetamol is an analgesic medicine that is freely available over-the counter and can be purchased without a receipt. It’s also used to control the fever, and is very effective in alleviating all kinds of pain, including headache, sprain or toothache. It affects the chemicals, known as prostaglandins (the ones that are associated with the perception of pain). By blocking them directly, Paracetamol makes the body less aware of the pain or injury. In general, Paracetamol is a safe medicine that can be used by children as well, but might be harmful to people with liver and kidney problems, or alcohol dependence.
Opioids are the third different type of painkillers and are based on naturally occurring drugs – chemicals, derived from the opium poppy. They attach themselves to protein receptors, known as opioid receptors, found in the brain, spinal cord, and many of the body organs. Once they’ve attached, they can reduce the perception of pain. Side effects, however, include drowsiness, confusion, constipation, and, if the dose is not measured properly, can even result in depressed respiration. Opioids also act directly on the reward circuit of the brain by flooding it with dopamine, which produces a feeling of ecstasy and might further help with alleviating severe pain. They’re strictly prescription medications and include drugs such as codeine, fentanyl, morphine, oxycodone and methadone. All of them act by relieving your pain and relaxing the muscles, mimicking your body’s own painkillers. However, since they’re incredibly potent, they’re also very addictive and should be treated with caution.
The type of painkillers you’re prescribed will largely depend on the type and severity of your pain. NSAIDs are generally prescribed, if there’s an inflammation present but are also not suitable if you have stomach ulcers. Weak opioids might be prescribed if you’re suffering from severe pain that is not affected by paracetamol or ibuprofen. Stronger, however, are only used in extreme cases, such as cancer-related pain or post-operative pain.