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How your medicine works

Painkillers are also known as analgesics. Some are purely pain relievers, with no effect on inflammation, e.g. paracetamol. They are also used to reduce fever associated with illness. Others, such as NSAIDs are also painkillers but they work primarily by reducing inflammation. Because the various types of analgesics act in different ways, they are sometimes used together.

NSAIDs work by blocking the chemicals that stimulate the inflammatory response, which are released after injury, and the result is a decrease in pain and swelling. Most NSAIDs begin to have a painkilling effect typically within 1 hour after taking them.

Painkillers such as paracetamol work by blocking the pain receptors in the brain from recognising the pain signals sent from the injury site and they will decrease the pain resulting from an injury. In most cases, paracetamol will take effect within 30 minutes after taking it.

‘Simple’ analgesics are called 'simple' because they are made up of only one type of drug (e.g. paracetamol).

Compound painkillers combine paracetamol or aspirin and a stronger form of pain control called an opioid, such as codeine. There are a number of different combinations, and these tend to have slightly more side effects than the simple analgesics.

Opioid drugs are used to relieve moderate to severe pain. The dose and how often tablets should be taken will vary according to levels of pain.

Other drugsTalking to your doctor