Morphine (Morphgesic SR, MXL, Zomorph, MST, Sevredol, Oramorph) | Cancer Research UK
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Morphine (Morphgesic SR, MXL, Zomorph, MST, Sevredol, Oramorph)

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This page tells you about the painkilling drug morphine, different ways of taking it, and its side effects. You can read about


What morphine is

Morphine is a type of painkiller called an opioid. Opioids are strong drugs similar to natural pain killing substances made in our body called endorphins. Opioid drugs were originally made from opium poppies and can now be man made in the laboratory. 

Morphine is available in different forms such as tablets, liquids, injections, suppositories or stick on patches. Your doctor or specialist nurse will help you choose the type that best controls your pain.

You can only get morphine on prescription from your doctor. You have morphine for moderate to severe pain. 


How morphine works

Opioid drugs such as morphine work by acting like the body’s natural painkillers known as endorphins. They block pain messages from travelling along the nerves to the brain. 


How you take morphine

You can take morphine in various ways. The type and dose of morphine you have depends on the pain that you have and the amount of drug you need to control your pain. Your doctor or nurse will give you information about on how much morphine to take and when to take 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. Don’t just stop taking morphine – you are likely to need to slowly reduce the amount you take. Always talk to your doctor or specialist nurse before you change your dose.

Morphine tablets or capsules

Many people take morphine as tablets or capsules. There are many different types and doses. You take them with a glass of water and swallow them whole. You can take them with or without food. They come in several doses from 5mg to 200mg. They are in different colours to help you tell the different doses apart. There are different brands of morphine tablets and capsules. Common types include Sevredol and Oramorph (short acting) and Zomorph and MST Continus or MXL (long acting).

Short acting tablets last for 2 to 4 hours per dose. Long acting (slow release) types last from 12 to 24 hours per dose. It may take a while to work out the right dose for you. Most people start on a short acting type or a liquid because it is easier and quicker to adjust the dose. Once your pain is under control, you will probably change to a long acting slow release tablet or capsule. 

You take the slow release type of morphine either once or twice a day. If you are taking it twice a day you take it in the morning and at night, for example at 8am and 8pm. It is really important that you take it regularly, even if you don’t feel that you have pain. The slow release tablets or capsules can take up to 48 hours to give you a steady dose and 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. The names for liquid morphine include Oramorph (short acting) and MST Continus suspension (long acting powder for dissolving in water).

Morphine suppositories

Morphine suppositories contain morphine inside a soft, waxy substance that is put into the back passage (rectum). The morphine is absorbed into the lining of the rectum and goes into the bloodstream. This is a fast way of getting drugs into your system and is helpful if eating or drinking are a problem.

It is easiest to put the suppository into your back passage if you lie on your side with your knees up towards your chest – whichever side is easiest for you. You should push the suppository in about 2cm (an inch) and wash your hands afterwards. If you are worried about it staying in, it can help to lie still for a few minutes afterwards. You need to avoid going to the toilet for at least an hour.

Morphine injections

If you can’t swallow, or are feeling very sick, you can have morphine as an injection. There are different ways of having the injections.

Injection under the skin (subcutaneous injection)

You usually have injections under the skin into the stomach, thigh or top of your arm. You may 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 the morphine under the skin continuously through a tiny needle connected to a pump called a syringe driver. It gives a continuous small volume of morphine. A nurse will change the pump every 24 to 48 hours. This way of having morphine is helpful for people who find it difficult to swallow.

Injection into a muscle

Some drugs are injected into a muscle (intramuscular injections), usually in your buttocks or upper thigh. This type of injection tends to start controlling pain within a few minutes. You may have stinging or a dull ache for a short time after this type of injection.

Injection into a vein

You can have morphine into your bloodstream (intravenously). You usually have it through a thin, short tube (a cannula) put into a vein in your arm or the back of your hand. Or you may have it through a central line, a portacath, or a PICC line. These are long, plastic tubes that give the drug directly into a large vein in your chest.


About side effects

We've listed the side effects associated with morphine below. You can use the links to find out more about each side effect. Where there is no link, please go to our cancer drug side effects section or use the search box at the top of the page.

You may have a few side effects. They may be mild or more severe. A side effect may get better or worse if you are taking morphine for some time. 

The side effects may be different if you are having morphine alongside other drugs.

Tell your doctor or nurse straight away if any of the side effects get severe.


Common side effects

More than 10 in every 100 people have one or more of these effects.

  • Constipation – drink plenty of water and eat fibre rich foods. Your doctor or specialist nurse will give you laxatives to help prevent constipation but let them know if you are constipated for more than 3 days
  • Feeling or being sick happens in about 3 out of every 10 people (30%). It is usually well controlled with anti sickness medicines
  • Drowsiness may be a problem at first, or when your dose is increased, but usually wears off after a few days. If you feel drowsy or sleepy do not drive or operate machinery

Occasional side effects

Between 1 and 10 in every 100 people have one or more of these.

  • Dizziness
  • A dry mouth
  • Headaches
  • Mood changes – you may feel very happy or feel very sad
  • Sudden jerking of the body due to muscle contractions
  • Confusion
  • Narrowing of the pupils in your eyes
  • Lowered sex drive (libido)
  • Difficulty sleeping
  • Griping pain in your stomach – if you have pain and haven’t opened your bowels tell your doctor or nurse
  • Extreme tiredness (somnolence)
  • Poor appetite
  • Being sick  – let your doctor or nurse know straight away if you have this
  • Excessive sweating, especially of the palms of the hands, soles of the feet and underarms
  • A skin rash
  • Weakness
  • Itching – let your doctor or nurse know if you have this as they can recommend things to help

Rare side effects

Fewer than 1 in 100 people have these.

  • An allergic reaction – let your nurse or doctor know straight away if you have a sudden skin rash, itching, breathlessness or swelling of the lips, face or throat
  • Feeling anxious and agitated
  • An overwhelming feeling of well being (euphoria)
  • Seeing or hearing things that are not there (hallucinations)
  • An increased risk of fits (seizures)
  • Muscle stiffness
  • Difficulty passing urine
  • Slowing of the heart beat or palpitations – tell your doctor or nurse as you may need a lower dose of morphine
  • A drop in blood pressure
  • Slowed breathing – tell your doctor or nurse as you may need a lower dose of morphine
  • Abnormal sensations, such as tingling or pricking (like pins and needles), caused by changes in nerve endings
  • Fainting
  • Eyesight changes
  • A feeling of falling or the room spinning (vertigo)
  • Flushing of the face
  • Low blood pressure
  • Difficulty breathing due to fluid build up around the lungs
  • Heartburn
  • Taste changes
  • A severe, itchy rash

Important points to remember

Talk to your doctor, pharmacist or nurse about any side effects so they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Other medicines

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies. Some drugs can react together.

Pregnancy and contraception

This drug may cause harm to a baby developing in the womb. It is important not to take this drug if you are pregnant. Talk to your doctor or nurse about effective contraception if needed before starting treatment.


Do not breastfeed during this treatment because the drug may come through in the breast milk.

Tolerance and addiction

People taking morphine for weeks or months can develop a physical dependence on the drug. This causes withdrawal symptoms if the drug is stopped. Your doctor or nurse will advise you how to reduce the does 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 you doctor or specialist nurse if you are worried about becoming addicted to morphine.


Related information

On this website you can read about 

Cancer and pain control

Treating cancer pain


More information about morphine

This page does not list all the very rare side effects of this drug that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at

If you have a side effect not mentioned here that you think may be due to this drug you can report it to the Medicines Health and Regulatory Authority (MHRA) at

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Updated: 29 June 2015