How Do Painkillers Work?

How Do Painkillers Work?

Painkillers are medicines that are used to treat pain. There are a large number of painkillers available and they all come in various different brand names. They can be taken:

  • By mouth as liquids, tablets, or capsules.
  • By injection.
  • Via the back passage (rectum) as suppositories.

Some painkillers are also available as creams, ointments or patches.

Even though there are a large number of painkillers available, there are only three main types (each works in a different way). They are:

  • Non-steroidal anti-inflammatory drugs (NSAIDS). Examples of NSAIDs include ibuprofen, diclofenac and naproxen. Aspirin is also an NSAID. However, it is mainly prescribed (in low doses) to help to keep the blood from clotting – for example, for people who have had a heart attack in the past.
  • Paracetamol.
  • Weak opioids and strong opioids (sometimes called opiates). Examples of weak opioids include codeine and dihydrocodeine. Although commonly described as ‘weak opioids’, they are extremely effective analgesics often used to treat severe pain; however, they can lead to significant addiction and adverse effects, so should not be underestimated. Examples of strong opioids include morphine, oxycodone, pethidine and tramadol. Many people who need strong opioids are in hospital.

Different types of painkillers are sometimes combined together into one tablet – for example, paracetamol plus codeine (cocodamol).

NSAIDs work by blocking (inhibiting) the effect of chemicals (enzymes) called cyclo-oxygenase (COX) enzymes. COX enzymes help to make other chemicals called prostaglandins. Some prostaglandins are involved in the production of pain and inflammation at sites of injury or damage. A reduction in prostaglandin production reduces both pain and inflammation. Not all NSAIDs are exactly the same, and some work in slightly different ways from others.

The type of painkiller your doctor will prescribe depends upon:

  • The type of pain you have.
  • Any other health problems you may have.
  • How severe your pain is.
  • The possible side-effects of the medicines.

Paracetamol is normally prescribed if your pain is not too serious and you do not have inflammation.

People who are in pain all the time are usually recommended to take painkillers regularly. For example, if you have been prescribed paracetamol you will normally take it four times a day, every day until the pain is better. Otherwise, you only need to take painkillers when you need them.

Like all medicines, painkillers should be taken for the shortest period of time possible, in the lowest dose that controls your pain. This is to help avoid any side-effects. Most people only need to take painkillers for a few days (for example, for toothache) or weeks (having pulled a muscle). However, some people have painful conditions and need to take painkillers on a long-term basis. Examples include people with rheumatoid arthritis, osteoarthritis, or chronic back pain.

It is not possible to list all the possible side effects of each painkiller in this leaflet. However, as with all medicines, there are a number of side effects that have been reported with each of the different painkillers. If you want more information specific to your painkiller then you should read the information leaflet that comes with the medicine.

It is very rare for anyone not to be able to take some type of painkiller. The main reason why you may not be able to take a painkiller is if you have had a serious side-effect or an allergic reaction to a particular type of painkiller in the past. Even if this happens, your doctor will usually be able to choose a different type of painkiller, which you will be able to take.

Aspirin cannot be taken by children under the age of 16 years, because there is a risk of the child developing Reye’s syndrome (very rare).

 

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