There are three main types of painkillers: non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol and opioids. Each works differently. Most people only need to take painkillers for a few days or weeks at most, but some people need to take them for a longer period of time. You can buy some pain relievers from pharmacies. This includes some NSAIDs, paracetamol and some weaker opioids (codeine or dihydrocodeine). These are sometimes called over-the-counter painkillers. If you buy painkillers that contain weak opioids and need to take them for more than three days, you should talk to your pharmacist or doctor.
1. Pain Relievers Definition
Pain relievers are medications used to treat pain. There are a large number of pain relievers available and they all come under different brand names. It can be taken:
- Liquids, tablets, or capsules by mouth.
- By injection.
- Through the back passage (rectum) as suppositories.
- Some pain relievers are also available as creams, ointments, gels or patches.
2. Types of Pain Relievers
Although there are a large number of pain relievers 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 prevent blood clotting – for example, in 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 generally described as ‘weak opioids’, they are highly effective analgesics that are often used to treat severe pain. However, they can cause significant addiction and adverse effects, so should not be underestimated. Examples of strong opioids include morphine, buprenorphine, oxycodone, pethidine, and tramadol. Many people who need stronger opioids are in the hospital.
Different types of painkillers are sometimes combined in one pill – for example paracetamol plus codeine (co-codamol).
In addition to the above, some antidepressants and antiepileptic drugs may be used to treat neuropathic pain.
3. Pain Relievers Working
NSAIDs work by blocking (blocking) the effect of chemicals (enzymes) called cyclooxygenase (COX) enzymes. COX enzymes help make other chemicals called prostaglandins. Some prostaglandins are involved in causing pain and inflammation at sites of injury or damage. Decreased prostaglandin production reduces both pain and inflammation. Not all NSAIDs are the same, and some work in slightly different ways than others.
Paracetamol – No one knows for sure how paracetamol works. But it also works by blocking COX enzymes in the brain and spinal cord
4. Usual Length of Treatment
Pain relievers should be taken for the shortest amount of time, 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 a toothache, for example) or weeks (for a muscle strain). 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.
5. Side Effects of Painkillers
It is not possible to list all possible side effects of every pain reliever in this leaflet. However, as with all medications, there are many side effects that have been reported with each of the different pain relievers. If you want more information about your painkiller, you should read the information leaflet that comes with the medicine.
- NSAIDs
Most people who take anti-inflammatory drugs, at least in the short term, have no, or only minor, side effects. When taken properly, the benefits usually outweigh the potential harms. In particular, many people take a short course of anti-inflammatory treatments for all kinds of painful conditions. However, there can be side effects, and sometimes very serious potential adverse effects. These include bleeding in the stomach and intestines, and cardiovascular problems. See the separate leaflet called Anti-inflammatory tablets (NSAIDs) for more details.
- Paracetamol
It is a safe drug and has very few side effects if you do not take the maximum recommended dose. However, paracetamol can be very dangerous if you take too much (overdose). Paracetamol overdose can happen accidentally, but some people overdose on purpose. The biggest problem with taking too much paracetamol is that it can permanently damage your liver and you can die from it.
- Opioids
The most common side effects are:
- Feeling sick (nausea) and being sick (vomiting) – especially at the start of treatment.
- Constipation.
- dry mouth
Opioids can also cause drowsiness and confusion. Some people can become tolerant (need to take more to get the same effect) of opioid painkillers and then become dependent on them. This includes opioids that can be bought at pharmacies. If you think you are becoming dependent on opioids and need to take higher and higher doses, talk to your pharmacist or doctor. See a separate leaflet called Strong Painkillers (Opioids) for more details.
Some pain relievers may interact with other medications you may be taking. It can cause reactions, or reduce the effectiveness of one or another treatment. Therefore, when you are prescribed a pain reliever, you should tell the doctor if you take other medications.