Morphine is a type of painkiller. You can only get it on prescription from your doctor and you have it for moderate to severe pain.

 It is also known as:

  • Morphgesic SR
  • MXL
  • Zomorph
  • MST
  • Sevredol
  • Oramorph
  • Actimorph

How does morphine work?

Morphine is a type of opioid. Opioids are strong drugs similar to natural pain killing substances made in our body called endorphins. It is extracted from opium poppies in a laboratory.

Opioids block pain messages from travelling along the nerves to the brain. 

What types of morphine are there?

You have morphine as:

  • tablets or capsules
  • liquids
  • injections
  • suppositories

Morphine tablets or capsules

You must take tablets and capsules according to the instructions your doctor or pharmacist gives you.

Many people take morphine as tablets or capsules. You take them with a glass of water, with or without food. 

There are different types and doses of morphine. They come in different colours to help you tell the doses apart. There are also different brands of morphine. Common types include Sevredol and Oromorph (short acting) or MST Continus and MXL (long acting).

Short acting morphine

Short acting morphine lasts for 2 to 4 hours per dose. Most people start on a short acting morphine tablet or liquid. This is because it is easier and quicker to adjust the dose. 

Once your pain is under control, you might change to a long acting (or slow release) tablet or capsule.

Long acting morphine

Long acting morphine lasts from 12 to 24 hours per dose. You take it either once or twice a day. 

If you are taking it twice a day, you should take it in the morning and at night, for example at 8am and 8pm. 

It is important that you take morphine regularly, even if you don't feel pain. The slow release tablets or capsules can take up to 48 hours to give you a steady dose. So if you stop and start, they won't work so well. 

Liquid morphine

Liquid morphine comes as a syrup or as a powder that you dissolve in water. 

There are different brands of liquid morphine such as Oramorph (short acting) and MST Continus suspension (long acting powder for dissolving in water). 

Morphine injections

When you can't swallow or are feeling sick, you can have morphine as an injection.

Injection under your skin (subcutaneous injection)

You usually have injections under the skin (subcutaneous injection) into the stomach, thigh or top of your arm.

You might have stinging or a dull ache for a short time after this type of injection but they don't usually hurt much. The skin in the area may go red and itchy for a while.

Some people have morphine under the skin continuously through a small needle connected to a pump called a syringe driver. It gives a continuous small volume of morphine. 

Your nurse will change the syringe driver every 24 or 48 hours. This way of having morphine is helpful for people who find it difficult to swallow.  

Injection into your muscle (intramuscular)

You have the injection into a muscle, usually into your buttock or upper thigh.

Injections into a vein (intravenous injection)

You can have morphine injected into your bloodstream.

You might have treatment through a long plastic tube that goes into a large vein in your chest. The tube stays in place throughout the course of treatment. This can be a:

  • central line
  • PICC line
  • portacath

When do you have morphine?

Your doctor, specialist nurse or pharmacist will help you choose the type and dose that best controls your pain. It depends on the pain you have and the amount of drug you need to control it.

You may feel drowsy when you first start taking morphine or if the dose is increased. If the drowsiness lasts more than a couple of days talk to your doctor or nurse.

You shouldn't just stop taking morphine suddenly. It is likely that you need to slowly reduce the amount you take. Always talk to your doctor or specialist nurse before you change your dose.

What are the side effects of morphine?

Side effects can vary from person to person. They also depend on what other treatment you are having. 

When to contact your team

Your doctor, nurse, or pharmacist will go through the possible side effects. They will monitor you closely during treatment and check how you are at your appointments. Contact your advice line as soon as possible if:

  • you have severe side effects 

  • your side effects aren’t getting any better

  • your side effects are getting worse

Early treatment can help manage side effects better.

We haven't listed all the side effects here. Remember it is very unlikely that you will have all of these side effects, but you might have some of them at the same time.

Common side effects

These side effects happen in more than 10 in 100 people (more than 10%). You might have one or more of them. They include:


Constipation Open a glossary item is easier to sort out if you treat it early. Drink plenty of fluids and eat as much fresh fruit and vegetables as you can. Try to take gentle exercise, such as walking. Tell your healthcare team if you think you are constipated. They can prescribe a laxative.

Feeling sick

This is usually mild. Let your doctor or nurse know if you have it.

Occasional side effects

These side effects happen in between 1 and 10 out of every 100 people (between 1 and 10%). You might have one or more of them. They include:

  • feeling confused
  • drowsiness
  • difficulty sleeping
  • dizziness
  • headaches
  • sudden jerking of the body due to muscle contractions
  • extreme tiredness and weakness
  • loss of appetite
  • rash or itchy skin
  • being sick – this should normally wear off after a few days and you can have tablets to help
  • generally feeling unwell

Rare side effects

These side effects happen in fewer than 1 in 100 people (fewer than 1%). You might have one or more of them. They include:

  • feeling agitated
  • seeing or hearing things that are not there
  • mood changes including feeling very happy or confident
  • fits (seizures)
  • stiffness or sudden movements of the muscles
  • tingling or numbness in the skin
  • fainting
  • problems with your eyes such as blurred vision
  • feeling of failing or the room spinning (vertigo)
  • heart problems such as palpitations and high or low blood pressure
  • redness (flushing) of the face
  • fluid build up in the lungs
  • slow and shallow breathing
  • changes in taste
  • indigestion
  • decreased bowel movement which can cause tummy pain
  • high levels of liver enzymes Open a glossary item found in a blood test
  • not being able to empty your bladder
  • swelling from a fluid up of fluid in the arms or legs

Coping with side effects

We have more information about side effects and tips on how to cope with them.

What else do I need to know?

Other medicines, foods and drinks

Cancer drugs can interact with medicines, herbal products, and some food and drinks. We are unable to list all the possible interactions that may happen. An example is grapefruit or grapefruit juice which can increase the side effects of certain drugs.

Tell your healthcare team about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies. Also let them know about any other medical conditions or allergies you may have.

Loss of fertility

It is not known whether this treatment affects fertility Open a glossary item in people. Talk to your doctor before starting treatment if you think you may want to have a baby in the future.

Contraception and pregnancy

This treatment may harm a baby developing in your womb. It is important not to become pregnant while you are having treatment. Talk to your doctor or nurse about effective contraception before starting treatment.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Treatment for other conditions

If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.

Tolerance and addiction

People taking morphine for weeks or months can develop a physical dependence. This causes withdrawal symptoms if morphine is stopped. 

Your doctor or nurse will advise you how to reduce the morphine dose gradually if necessary. Don't stop taking morphine suddenly. 

Some people can also develop a psychological dependence (addiction) to morphine. This may be more likely in people who have problems with alcohol or drug use. 

Talk to your doctor, specialist nurse or pharmacist if you are worried about becoming addicted to morphine.

More information about this treatment

For further information about this treatment and possible side effects go to the electronic Medicines Compendium (eMC) website. You can find the patient information leaflet on this website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

  • Electronic Medicines Compendium 
    Accessed October 2022

  • Management of cancer pain: ESMO Clinical Practice Guidelines
    CI Ripamonti and others
    Annals of Oncology, 2011. Volume 22, Supplement 6

  • Palliative care for adults: strong opioids for pain relief
    National Institute for Health and Care Excellence, 2012

Last reviewed: 
02 Dec 2022
Next review due: 
02 Dec 2025

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