For pain associated with inflammation, such as back pain or headaches, paracetamol and anti-inflammatory painkillers work best.
If the pain is caused by sensitive or damaged nerves, as is the case with shingles or sciatica, it is usually treated with tablets that change the way the central nervous system works.
The aim of taking medication is to improve your quality of life. All painkillers have potential side effects, so you need to weigh up the advantages of taking them against the disadvantages.
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Paracetamol is used to treat headaches and most non-nerve pains.
Two 500mg tablets of paracetamol up to four times a day is a safe dose for adults. Side effects are not common and this dose can be taken regularly for long periods.
Overdosing on paracetamol can cause serious side effects, however, so don't be tempted to increase the dose if your pain is severe.
If the pain lasts for more than three days, see your GP.
More on paracetamol.
So-called non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, diclofenac and naproxen, seem to work better when there is clear evidence of an inflammatory cause, such as arthritis or an injury.
They should not be used for long periods unless you have discussed it with your doctor.
If you take them for long periods, there's an increased risk of stomach upset, including bleeding, and kidney and heart problems.
Don't take more than the recommended dose, as this will increase the risk of serious side effects.
More on ibuprofen.
Aspirin is another type of NSAID.
It produces the same kind of side effects as other NSAIDs, but is not as effective as a painkiller, which means it's not usually prescribed for pain.
It is dangerous for children under 16.
Codeine doesn't work very well on its own. It works better when combined with paracetamol in a single pill.
You can buy co-codamol (paracetamol and low-dose codeine) over the counter. Higher-dose codeine has to be prescribed.
Codeine and other medium-strength prescribed painkillers can cause dependency, which means that when you stop taking them you may feel unwell for a short period.
If you need more and more of these drugs, contact your GP or other healthcare professional for advice.
Effervescent painkillers are high in salt, containing up to 1g per tablet.
Too much salt can raise your blood pressure, which puts you at increased risk of health problems such as heart disease and stroke.
You may want to consider switching to a non-effervescent painkiller, especially if you've been advised to watch or reduce your salt intake.
Amitriptyline and gabapentin
Amitriptyline is a drug for depression and gabapentin is a drug for epilepsy.
Each of these medicines can also be used to treat pain caused by nerve sensitivity or nerve damage, such as shingles, diabetes nerve pain and sciatica.
You don't have to have depression or epilepsy for these tablets to help your nerve pain.
Amitriptyline and gabapentin both have to be prescribed by a GP.
Side effects include drowsiness and dizziness.
Morphine and morphine-like drugs (such as oxycodone, fentanyl and buprenorphine) are the strongest painkillers there are.
Some come as a patch, but they all work in similar ways and should only be used for severe pain.
They will only be prescribed after consultation with your GP or a pain specialist. The dose and your response will be closely monitored. These drugs should only be used as part of a long-term plan to manage your pain.
Read about the NHS help on offer if you have persistent pain.
Further advice on painkillers
Talk to your pharmacist or GP, or call NHS 111 if you need more advice on painkillers.
Common questions about medicines
Article provided by NHS Choices
Record managed by Oxfordshire Family Information Service