International guidelines recommend the types of painkillers that are most effective for different levels of pain. This is known as the analgesic ladder and recommends specific types of painkiller for mild pain, moderate pain and severe pain.

1 Mild pain
Mild painkillers or anti-inflammatory drugs
(e.g. aspirin or ibuprofen) Can be used with other drugs

2 Moderate pain
Weak opioid painkillers
(e.g. codeine) Can also use with other drugs

3 Severe pain
Strong opioid painkillers
(e.g. morphine) Can use with other
drugs

Painkillers such as paracetamol, aspirin and ibuprofen are often effective in controlling mild pain and can be bought from the chemist. Aspirin and ibuprofen can reduce inflammation as well as relieving pain, but they can cause indigestion and occasionally irritation of the stomach lining, which may make it bleed. To reduce the risk of stomach problems you should not take aspirin or ibuprofen on an empty stomach or with alcohol.

Never take a higher dose of these painkillers than is recommended on the packet. Check with your doctor, nurse or pharmacist before taking them, in case they interact with other medicines you are taking or are not suitable for you. You can tell if any medicines or tablets you buy from the chemist contain aspirin or ibuprofen as it should say so on the packet: check with the pharmacist if you are not sure.

Moderate pain is treated with low dose opioid drugs, such as codeine phosphate, dihydrocodeine (DF118 Forte®, DHC Continus®), dextropropoxyphene or tramodol. These are often combined with paracetamol in a single tablet, (e.g. co-codamol, co-dydramol or coproxamol). These combinations of painkillers have brand names such as Tylex®, Remedeine®, Solpadol®and Distalgesic®. They are available only on prescription from a doctor and the paracetamol content limits the number of these tablets that can be taken in one day.

All opioid painkillers cause constipation, and your doctor may prescribe a laxative for you to take with these drugs. This type of painkiller may cause drowsiness, and alcohol may increase the level of drowsiness. Some drugs may cause a dry mouth, which can be a nuisance. Look in our section on coping with a dry mouth for further information.

Strong painkillers are known as opioid analgesics. Morphine and diamorphine are the most commonly used of these drugs. Other strong painkillers are fentanyl, oxycodone, hydromorphone, buprenorphine, and methadone.

As with any painkiller, it is important to find the most effective dose for each person. Two people with the same type of cancer, at the same stage of disease, may need entirely different doses of the drug. It is usual to start at a low dose and build up gradually to get the best pain relief. The dose can be changed and/or other painkillers can be used, so that the pain is kept under control.

It can take a few days to adjust to taking strong painkillers. Like the painkillers in the `moderate' group, they may cause drowsiness. This usually passes within a few days once you have got used to the dose. Strong painkillers affect people in different ways, but if you are planning to drive, or to work with machinery, you should check with your GP first, and test your general reactions and alertness. It is fine to drink small amounts of alcohol while you are taking strong painkillers, but it increases the likelihood of drowsiness.

Painkillers may make you feel tired. Talk to your GP about how this may affect you at home and at work.

All of the strong painkillers have similar side effects. The most common physical side effects are constipation and sickness, which can be relieved with other drugs. Constipation is so common that people taking strong painkillers should use a laxative throughout their treatment. Some laxatives soften the stools and make them easier to pass, while others stimulate the bowel so that it pushes the stools along more quickly. A combination of the two types is often the best solution and your doctor will be able to advise which are the best ones for you to take.

Some people feel sick when they first start taking strong painkillers so they may be advised to use an anti-sickness drug (anti-emetic) for at least the first week of treatment.

A dry mouth can be a side effect of these drugs and can be a nuisance. This does not need drug treatment and can be relieved by drinking plenty of liquid. Chewing gum can help. Cancerbackup has a separate section on how to cope with a dry mouth.

If the dose of strong painkillers is too high, they can cause slow, deep breathing and low blood pressure, which can lead to a feeling of dizziness or faintness. Let your doctor know straight away if you have any of these effects.

The most common strong painkillers are described below. All strong painkillers cause the same sort of side effects, but some suit some people better than others, so if your pain is not well controlled or the side effects are causing you discomfort let your doctor or nurse know. Another type of painkiller can then be tried or the dose can be adjusted.

Morphine
Morphine is the most commonly used strong painkiller and can be taken in various ways:

• short acting tablets (Sevredol®)
• long-acting tablets and capsules (Morcap SR®, MST Continus®, MXL®, Zomorph®)
• short acting syrup (Oramorph®, Sevredol®)
• granules in liquid (MST Continus®)
• suppositories inserted into the back passage (Moraxen®, morphine)
• injection into the muscle (morphine sulphate), (Cyclimorph®- morphine combined with an anti-sickness drug)
• injection into the vein (morphine sulphate) (Cyclimorph®- morphine combined with an anti-sickness drug)

A short-acting type of morphine is usually given every four hours to begin with, so that the dose can be adjusted until the pain is well controlled. It can be taken as a tablet or a liquid. Liquid morphine has a bitter taste that can be improved by mixing it with a fruit drink. Once the correct dose has been found, most people take slow release tablets or capsules. The morphine dose is released very slowly, over a period of either 12 or 24 hours, depending on which you are taking. A slow release liquid has also been developed which, like the tablets, releases morphine slowly over 12 hours. The liquid is made by mixing granules in water - it is then taken as a drink.

If people are not able to swallow or are being very sick, there are other options such as injections or suppositories. Moraxen is a suppository containing morphine, which releases a constant amount of morphine over a period of at least 24 hours. After the suppository has been in place for about 24 hours, it should be pushed out from the rectum, using the same muscles as you would during a bowel movement.

As well as the usual side effects of strong painkillers, morphine can give a sense of well-being (euphoria) and some people feel ``detached'' from what is going on around them.

A few people find that the side effects of morphine are too uncomfortable for them. They may have continuing drowsiness or sickness, which is not relieved by the usual medicines. Other strong painkillers are then used, such as fentanyl, methadone, oxycodone or hydromorphone as they may suit the person better, although they may also cause similar side effects.

Fentanyl
Fentanyl is another type of opioid painkiller. It can be given by injection, skin patch or as a lozenge.

The patches (Durogesic®) look like waterproof plasters. They are stuck to your skin, and the drug is released slowly through the skin. The patch needs to be changed every three days, and the new patch is placed on a different area of skin. The patches can be convenient as you don't need to remember to take tablets regularly.

Fentanyl is also available as injections (Rapifen®) or as a short-acting lozenge (Actiq®). The injection or lozenge can be used when patches have just been applied, as it takes around a day for fentanyl to reach its maximum level in the blood. The short-acting fentanyl can also be helpful if people need a dose of fentanyl in addition to the patch, to help with a painful procedure, such as having a dressing changed.

The side effects are the same as for all strong painkillers and the patches may also cause a slight skin rash on the area of skin they are applied to. Fentanyl causes less constipation for some people than other types of opioid drugs.

Warmth can increase the absorption of fentanyl through the skin, so if you have a high temperature, it is important to let your doctor or nurse know immediately. It is also important to avoid heating the skin patch, so care should be taken when bathing or showering.

Hydromorphone
Hydromorphone (Palladone®) is available as short-acting and long-acting capsules. The side effects are the same as for all strong painkillers, as previously mentioned.

Methadone
Methadone is available as short-acting tablets or syrup, or for injection into a muscle or under the skin.

Buprenorphine
Buprenorphine is available as a patch (Transtec®) that is changed every 3 days (similar to fentanyl) or as a lozenge (Temgesic®) that is dissolved under the tongue every 6 to 8 hours, or by injection.

Oxycodone
Oxycodone is given as short-acting capsules or liquid (OxyNorm®) or long-acting tablets (OxyContin®).

Diamorphine
Diamorphine is available as tablets, or for injection into the vein, muscle or under the skin. It is most commonly given by injection under the skin.

If people are unable to swallow and need to have their painkillers given by injection, diamorphine is the most commonly used drug. A constant dose of diamorphine can be given continuously by using a small pump known as a syringe driver. This method of giving drugs is known as continuous infusion and is often very effective in maintaining good pain control.

A syringe of diamorphine is attached to the syringe driver and the drug is slowly released through a small needle under the skin. Less commonly, the diamorphine is given slowly through a needle into a vein, or into the fluid around the spinal cord, which is known as intrathecal analgesia or an epidural. The amount of the drug can be adapted very carefully to the person's changing needs. There are many different types of pump. Small syringe drivers (pumps) are battery powered and clip easily onto your belt. They can also fit into a pocket or can be placed in a specially designed holster that fits under your arm, so that you can be up and about as usual.

If you cannot move around much, and stay mainly by your bed or chair, a larger syringe driver may be used, which needs to be plugged into an electrical socket.

With some syringe drivers it is possible for people to control the amount of painkiller they receive, by pressing a button attached to the syringe driver whenever they feel pain. Pressing the button gives an extra, small dose of the painkiller and is called patient-controlled analgesia. Drugs to control other symptoms, such as feelings of sickness and vomiting, can be added to the same syringe.