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 can be effective for different types of pain.  Your doctor or nurse will discuss your pain management with you. Once they have assessed your pain, they will prescribe the best painkillers to help control it. You may also be given other drugs to help relieve pain. These include steroids and muscle relaxants.

To get your pain under control, you usually start by taking a short-acting painkiller. This provides quick pain relief that lasts until you take the next dose. You usually need to take short-acting painkillers every 4 to 6 hours. The dose can be adjusted until your pain is controlled. When the doctor knows the dose you need, they may change you to a slow-release or long-acting painkiller. You usually need to take long-acting painkillers twice a day.

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
  • non-steroidal anti-inflammatory drugs (NSAIDs) – for example, ibuprofen.

You can buy these drugs over the counter, from a pharmacy (chemist) or supermarket. Take them as explained in the packet. You may need to take some medicines with food, or after eating.

Other medicines you can buy, 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 medicines.

  • Paracetamol

    Paracetamol can be used for most types of mild pain. It does not cause many side effects, but it is very important not to take more than the recommended dose. Higher doses can damage the liver. If you think you have taken too much, talk to your doctor or nurse as soon as possible.

  • 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 from a supermarket or pharmacy. Check with your doctor or nurse before taking NSAIDs. They do not work for everyone. They should not be taken with some medicines.

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

    NSAIDs can cause indigestion and may irritate the lining of the stomach. Your doctor may prescribe another drug 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 into 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 are sometimes called ‘morphine-like’ 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 drugs combine an opioid with paracetamol. 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 a day. If you are prescribed a combination drug and it is not controlling your pain, tell your doctor, so they can give you stronger painkillers. Some doctors prescribe a low dose of a stronger opioid to treat mild to moderate pain.

We have the answers to common questions about painkillers.

Painkillers for moderate to severe pain

Moderate to severe pain is usually treated with strong opioids.

Your doctor usually prescribes a low dose of the opioid drug to start with. They gradually increase the dose until your pain is well controlled.

It can take a few days to adjust to taking a stronger opioid, or a higher dose of opioid.

Tell your doctor or nurse if you have side effects from the drug they have prescribed. 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. They often work well when given together so it is important to take these as well.

The most commonly used strong painkillers are:


You can take morphine as:

  • short-acting tablets
  • liquid that you swallow
  • long-acting tablets or capsules
  • a short-acting injection
  • suppositories inserted into the back passage (rectum).

Morphine is known by different brand names. Short-acting preparations include Oramorph® and Sevredol®. Long-acting preparations include Morphgesic SR®, MST Continus®, MXL®, and Zomorph®.

You usually take a short-acting type of morphine every 2 to 4 hours. This is usually 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 over 24 hours to control the pain, they usually change you to long-acting drugs. These drugs release the dose of morphine slowly over 12 or 24 hours. You may still need to take short-acting morphine in between if you get breakthrough pain.

Taking both long-acting and short-acting morphine gives you better control of the pain. This helps you to do the things you want without too many changes to your daily life.

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.

You can take oxycodone as:

  • short-acting tablets, capsules, or liquid that you take every 4 to 6 hours
  • long-acting tablets that you take every 12 hours
  • an injection given under the skin or continuously through a syringe pump.

There are many different brand names of oxycodone. Short-acting preparations include Lynlor®, OxyNorm®  and Shortec®.

Long-acting preparations include Ixyldone®, Longtec® and OxyContin®.


You may have fentanyl once your doctor or nurse has worked out the dose of opioid you need.

Fentanyl patches

Fentanyl patches are waterproof plasters you stick on your skin. They release the drug at a constant rate through your skin. You change the patches every 3 days. You put the new patch on a different area of skin.

When you first use the patch, it takes around 12 to 24 hours for the fentanyl to reach the correct level in the blood. During this time, you usually need to take a short-acting opioid drug, to keep the pain under control.

If you are using fentanyl patches, it is important to:

  • Take the old patch off before applying a new one. 
  • Write the date on the patch when you apply it to remind you when to change it.
  • Place patches on areas of dry flat skin that have little or no hair.
  • Stop the patch from getting hot by keeping it away from the sun, hot water, heat pads and hot water bottles.
  • 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.

There are several different brand names of fentanyl patches. They include Durogesic® and Victanyl®.

Other ways of taking fentanyl

You can take fentanyl by mouth, in several different ways. You put the following drugs between your cheek and gum:

  • 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®)

It is also available as a nasal spray (Instanyl® or PecFent®).

The drug is absorbed quickly into the body from your mouth or nose. Fentanyl given this way is usually for breakthrough pain.

Other strong painkillers

Other opioids that are less commonly used include:

  • Buprenorphine

    This may be given as:

    • low dose skin patch you change every 7 days
    • high dose skin patch you change every 3 to 4 days
    • tablet you dissolve under the tongue every 6 to 8 hours.
  • Diamorphine

    Diamorphine is given as an injection. It is usually given continuously through a small needle under the skin connected to a syringe pump. Diamorphine changes into 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 liquid
    • long-acting tablets.
  • Methadone

    Methadone (Physeptone®) may be given as:

    • a tablet
    • a liquid
    • an injection, but this is rare.

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

  • Alfentanil

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

We have the answers to common questions about painkillers.

Side effects of strong painkillers

Some people get side effects from painkillers, especially opioids. 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 get used to the dose. If you are still feeling drowsy after a week, talk to your doctor or nurse. They can check the dose and see if you are taking any other medicines that might cause drowsiness.

Drinking alcohol can make drowsiness worse. See our information on common questions about painkillers for more advice. If you feel drowsy, avoid things like driving or operating machinery.

You should not drive when you start to take strong painkillers or if the dose has changed. This is because they may slow your reactions. Your body needs time to get used to the medication and dose.

If you get drowsy after you have been taking strong painkillers for a while, tell your doctor or nurse. This sometimes happens if you have had treatments to shrink the cancer, which has helped to reduce the pain.


Constipation is a common side effect of strong painkillers. Your doctor will need to prescribe you laxatives. There are different types of laxative. Some soften stools (poo) 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 any laxatives without checking with your doctor, nurse or pharmacist first.

We have more information on how to cope with constipation.


Some people may feel sick for a few days when they start taking painkillers. Some people may occasionally be sick (vomit). This usually gets better within a week. Your doctor may 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 change your painkiller or the anti-sickness medicine.

Dry mouth

Strong painkillers can make your mouth dry. If this happens, tell your doctor or nurse. There are different things that can help:

  • taking regular sips of water – fizzy water may feel more refreshing
  • sucking ice cubes or lollies
  • chewing sugar-free gum
  • using an artificial saliva product
  • keeping food moist by adding sauces and gravies.

Other side effects

Some people have other side effects with painkillers. These include: 

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

If you have any of these, or any other side effects, let your doctor know straight away. They can change your dose of painkiller or give you another type. Some strong painkillers may suit you better than others.

About our information

  • 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 professionals and people living with cancer. It has been approved by our Senior Medical Editor, Dr Ollie Minton, Macmillan 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.

Date reviewed

Reviewed: 01 August 2022
Next review: 01 August 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.