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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 and its side effects. You can read about


What morphine is

Morphine is a type of painkiller called an opioid. There are different types of opioids and they are 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. It is similar to the drug diamorphine. You have morphine for moderate to severe pain. Opioids work by acting like the body’s natural painkillers known as endorphins. They control pain by blocking pain messages to the brain. You can find out more in our section about cancer and pain control.

Because morphine is an opioid, some people worry about becoming addicted. When you take an opioid to control pain, it is unlikely that you will become addicted. The body uses the drug to control pain, not to give you a high. You can read more information about fear of addiction in our treating pain section.


How you take morphine

You can take morphine in various ways including as

The type and dose of morphine you have depends on the pain that you have and the amount 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. 

Morphine tablets

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. The tablets 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. Common types include Sevredol and Oramorph (short acting) and Zomorph and MST Continus (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 tablet or 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. You take the slow release tablets either once or twice a day. If you are taking them twice a day you take them in the morning and at night, for example at 8am and 8pm. It is really important that you take them regularly, even if you don’t feel that you have pain. The slow release tablets can take up to 48 hours to give you a steady dose and if you stop and start, they won't work so well. 

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.

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 are absorbed through the lining of the back passage (rectum). 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 after putting it in. You need to avoid going to the toilet for at least an hour afterwards.

Morphine injections

If you can’t swallow, or are feeling very sick, you can have morphine as an injection into your

You may have the morphine through a pump called a syringe driver. This delivers liquid from a syringe to a needle put just under the skin (subcutaneously). It gives you a small volume of morphine continuously. A nurse will change the pump every 24 to 48 hours.


Common side effects

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

  • 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%) but 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

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 low in mood
  • Confusion
  • Narrowing of the pupils in your eyes
  • Lowered sex drive (libido)
  • Griping pain in your stomach – if you have pain and haven’t opened your bowels tell your doctor or nurse

Rare side effects

Fewer than 1 in 100 people have these.

  • A skin rash
  • Difficulty passing urine
  • Slowing of the heart beat or palpitations – tell your doctor or nurse as you may need a lower dose of morphine
  • Drop in blood pressure
  • Slowed breathing – tell your doctor or nurse as you may need a lower dose of morphine

Important points to remember

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

  • How many times you've had the drug before
  • Your general health
  • The amount of the drug you have (the dose)
  • Other treatments you are having

Talk to your doctor, pharmacist or nurse about all your 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.

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

Breastfeeding is not advisable while you are taking morphine because the drug may come through in the breast milk.


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: 14 May 2013