Types of painkillers

There are different types of painkillers and ways of taking them. Your medical team will find the best painkiller to help you manage cancer pain.

Types of painkillers to help with cancer pain

Pain is often described as being mild, moderate or severe. Different types of painkillers are effective for different levels of pain. Once your doctors and nurses have assessed your pain, they will prescribe the best painkillers to help control it. They may also prescribe other medicines to take with the painkillers to help reduce pain. These include steroids and muscle relaxants.

At first, you usually take a short-acting painkiller. These provide quick pain relief that lasts until you take the next dose. The dose can be adjusted until your pain is well controlled. When the doctor knows how much of the painkiller you need to control your pain, you may change to a slow-release or long-acting painkiller.

We have more information about pain and how it is assessed.

Painkillers for mild pain

If pain is mild, it can often be controlled with simple painkillers such as paracetamol, and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen.

You can buy either of these drugs from a pharmacy or supermarket. Be aware that some other medicines, such as cold and flu remedies, may also contain paracetamol or anti-inflammatory drugs.

Be careful that you do not take more than the recommended dose of any painkillers. If you are unsure, check with a pharmacist before buying any over-the-counter medicines.

  • Paracetamol

    Paracetamol can be used for most types of mild pain. It has few side effects, but it is very important not to take more than the recommended dose. Higher doses can damage the liver.

  • Anti-inflammatory drugs

    Non-steroidal anti-inflammatory drugs (NSAIDs) are often used to relieve pain and reduce inflammation and swelling. They may be taken on their own or with other types of painkillers.

    Ibuprofen is an NSAID that has different brand names, including Brufen® and Nurofen® . You can buy these drugs over the counter from a supermarket or pharmacy. Check with your doctor or nurse before taking NSAIDs.

    Other anti-inflammatory medicines, such as diclofenac and naproxen, need to be prescribed by a doctor.

    These drugs can cause indigestion and may irritate the lining of the stomach. It is important to take them with food or a drink of milk. Your doctor may prescribe another medicine to help protect your stomach. If you have had problems with your stomach your doctor may advise taking a different type of painkiller. If you have muscle or joint pain, they may suggest anti-inflammatory skin patches or gel that you rub onto the skin.

    When taking these drugs, always check the recommended dose on the packet and never take a higher dose.

Painkillers for mild to moderate pain

Doctors usually treat mild to moderate cancer pain with drugs called opioids. These may also be called ‘morphine-type’ medicines. There are different types of opioids and some are stronger than others. Opioid drugs used for mild to moderate pain include:

  • codeine phosphate
  • dihydrocodeine (DF118 Forte®, DHC Continus®)
  • tramadol.

Some people are prescribed these drugs combined with paracetamol in a single tablet. For example, co-codamol is a combination of codeine and paracetamol. There is a limit to the number of these tablets you can take in one day. If the pain is not controlled, tell your doctor or nurse so they can give you stronger painkillers. Some doctors prescribe a low dose of a stronger opioid (see below) to treat mild pain.

Painkillers for moderate to severe pain

Doctors usually treat moderate to severe pain with stronger opioids.

Your doctor usually prescribes you a low dose of the opioid drug to start with. They gradually increase it until it reaches a dose that controls your pain. If the pain gets worse, they can increase the dose of your painkiller.

It can take a few days to adjust to taking a stronger opioid, or a higher dose. Your doctor may increase or decrease the dose of the painkiller depending on the level of pain.

Stronger painkillers can have more side effects. If you have side effects, tell your doctor or nurse. They may be able to prescribe a different type of strong painkiller that does not cause the same side effects.

Your doctor may prescribe other drugs, such as paracetamol or ibuprofen, to take regularly along with strong painkillers. It is important to take these as well.

The most commonly used painkillers are:


You can take morphine as:

  • short-acting tablets (Sevredol®)
  • short-acting syrups (Oramorph®)
  • a short-acting injection
  • long-acting tablets and capsules (Morphgesic SR®, MST Continus®, MXL®, Zomorph®)
  • long-acting granules you mix with water to make a drink MST Continus®.

To begin with, you usually take a short-acting type of morphine every 2 to 4 hours. You take this as a tablet or a liquid. Your doctor or specialist nurse will tell you how often to take it. Liquid morphine has a bitter taste but mixing it with a fruit drink can help.

When the doctor knows how much morphine you need to control the pain, they usually change you to long-acting drugs. These drugs release the dose of morphine slowly over either 12 or 24 hours. You may still need to take short-acting morphine in between if you get breakthrough pain.

Taking both types of pain relief helps you to have better control of the pain and manage it as needed.

You can also have morphine as an injection under the skin or through a syringe pump.


If you cannot have morphine, or it is not working well for you, your doctor may prescribe oxycodone. Oxycodone can also help if there are problems with how well your kidneys or liver are working.

You can take it by mouth as:

  • short-acting capsules or liquid that you take every 4 to 6 hours, such as Lynlor®, OxyNorm®, Shortec®
  • long-acting tablets that you take every 12 hours, such as Abtard®, Carexil®, Ixyldone®, Leveraxo® Longtec®, OxyContin®, Reltebon® or Targinact® (Targinact® also contains naloxone to help prevent constipation).

Oxycodone can also be given by injection under the skin. Or it can be given continuously through a syringe pump.


You may have fentanyl once your doctor or nurse has worked out the right dose of opioid for you. You can have fentanyl in different ways.

Fentanyl patches

These look like waterproof plasters. You stick them onto your skin and they release the drug at a constant rate through your skin. You change the patches every 3 days and put the new patch on a different area of skin.

When you first use the patch, it takes around 12 to 24 hours for fentanyl to reach its level in the blood. During this time, you usually need to take a short-acting drug, such as morphine, to keep the pain under control. If you are using fentanyl patches:

  • Place patches on areas of dry flat skin that have little or no hair.
  • Write the date on the patch so you remember when to change it.
  • Protect the patch from the sun, hot water, heat pads and hot water bottles, to stop it getting hot.
  • Let your doctor or nurse know if you have a temperature. This may affect how the medicine is absorbed through your skin.
  • Tell your nurse if the patch causes a skin rash or itching.

Other ways of taking fentanyl

You can also take fentanyl by mouth, by placing it between your cheek and gum, where it is quickly absorbed. There are different types, but the following are all taken in the same way as fentanyl:

  • a short-acting lozenge (Actiq® or Cynril®)
  • a tablet (Effentora®)
  • a dissolvable film (Breakyl®).

You can also take fentanyl as:

  • a tablet you put under the tongue (Abstral®)
  • a nasal spray (Instanyl®).

The drug is absorbed into the body from these areas and works quickly. It is usually used for breakthrough pain.

Other strong painkillers

Other opioids that are less commonly used include:

  • Buprenorphine

    This may be given as:

    • a skin patch you change every 7 days or 3 days
    • a tablet you dissolve under the tongue every 6 to 8 hours.
  • Diamorphine

    Diamorphine is a drug that is given as an injection. It is usually given continuously through a small needle under the skin connected to a syringe pump. Diamorphine changes to morphine in the body. You may have diamorphine if you are being sick or if you find it difficult to swallow tablets or liquids.

  • Tapentadol

    Tapentadol (Palexia®) can be given as:

    • short-acting tablets
    • a short-acting syrup
    • long-acting tablets.
  • Methadone

    Methadone (Physeptone®) may help reduce nerve pain. It can be given as

    • a tablet
    • a syrup.

    It is usually only given under close supervision from a specialist palliative care doctor or pain doctor.

  • Alfentanil

    Alfentanil (Rapifen®) is another strong painkiller that is only given by injection or continuously through a syringe pump. It is more likely to be used if a person’s kidneys are not working well.

Side effects of strong painkillers

As with most medicines, some people get side effects from strong painkillers. But they will not affect everyone and most side effects improve after a few days. Here are some of the most common ones:


Strong painkillers may make you feel drowsy when you first start taking them. This usually improves within a few days once you are used to the dose. Talk to your doctor or nurse if it does not.

Other drugs you may be taking could also cause drowsiness. Drinking alcohol can make drowsiness worse. See our information on frequently asked questions about painkillers for more advice. If you feel drowsy, avoid things like driving or operating machinery.

Tell your doctor or specialist nurse if you get drowsy after you have been taking strong painkillers for a while. This sometimes happens if you have had other treatments to shrink the cancer, which has helped to reduce the pain. You may need a lower dose or a different type of painkiller.


Constipation is a common side effect of strong painkillers. Your doctor will need to prescribe you laxatives. Some laxatives soften stools and make them easier to pass. Others stimulate the bowel to push the stools along more quickly. You may need a combination of laxatives to prevent constipation.

Do not take laxatives yourself. Ask your doctor or nurse first.


Some people may feel sick for a few days when they start taking painkillers. Your doctor will prescribe an anti-sickness (anti-emetic) drug for at least the first week of treatment. If it does not improve, tell your doctor. They may need to prescribe you a different painkiller.

Dry mouth

Strong painkillers can make your mouth dry. Tell your doctor or nurse if this happens.

Other side effects

If the dose of a strong painkiller is too high, it may cause other symptoms.

It could make you:

  • feel forgetful or confused
  • have vivid dreams and hallucinations (seeing things that are not real)
  • feel dizzy or faint
  • have low blood pressure
  • have slower, deeper breathing.

Let your doctor know straight away if you have any of these side effects.

If side effects are a problem, tell your doctor or nurse. They can change the dose of painkiller or give you another type. Some strong painkillers may suit you better than others.

About our information

  • References

    Below is a sample of the sources used in our cancer pain information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Fallon, Giusti, Aielli et al. Management of cancer pain in adult patients: ESMO Clinical Practice Guidelines. Annals of Oncology. 2018. 29: 166–191.

    O'Brien, Christrup, Drewes, et al. European Pain Federation position paper on appropriate opioid use in chronic pain management. European Journal of Pain. 2017. 21: 3-19.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Viv Lucas, Consultant in Palliative Medicine.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.