Diamorphine | Cancer Research UK
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What diamorphine is

Diamorphine is a pain killing drug. You have it for moderate to severe pain. It can also reduce breathlessness caused by a build up of fluid around the lung (a pleural effusion). 

You can only get diamorphine on prescription from your doctor. It is a type of opioid.


How diamorphine works

Diamorphine works by acting like the body’s natural painkillers known as endorphins. These control pain by blocking pain messages to the brain.


How you have diamorphine

Diamorphine is available as injections or tablets. The dose you have depends on the level of your pain and the amount needed to control it. Your doctor or nurse will give you instructions on how much diamorphine to have and when to have it.

Diamorphine injections

A doctor or nurse dissolves the white diamorphine powder in liquid in a syringe.

You may have diamorphine as an injection into your vein (intravenously) through a small needle put into your vein (a cannula). Or you can have it into your fatty tissue as an injection just under the skin (subcutaneously)

Some people have diamorphine as an injection into the muscle (intramuscularly) but this is not common.

You usually have the injections every 4 hours.

Some people have diamorphine into the fatty tissue through a small needle put just under the skin and connected to a pump called a syringe driver. The pump gives you a small amount of diamorphine continuously. A nurse changes the pump every 24 to 48 hours. Or the nurse may teach you or your carer how to do this.

Diamorphine tablets

You swallow the tablets with plenty of water. You usually take them every 4 hours. It is very important that you take tablets according to the instructions your doctor or pharmacist gives you. 


About side effects

We've listed the side effects associated with diamorphine. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects 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 as you carry on taking diamorphine. 

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

The side effects may be different if you are having diamorphine with other medicines.


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. Let them know if you are constipated for more than 3 days
  • Feeling or being sick is usually well controlled with anti sickness medicines
  • Drowsiness may be a problem at first, or when your dose is increased, but this usually wears off after a few days
  • Sweating
  • A dry mouth – this affects most people

Occasional side effects

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

  • Dizziness – don't drive or operate machinery if you have this
  • Headaches
  • Mood changes – you may feel very happy or feel very sad or depressed
  • Confusion
  • Skin rashes and itching
  • Narrowing of the pupils in your eyes
  • A lowered sex drive (libido)
  • Griping pains in your stomach – tell your doctor or nurse if you have pain and haven’t opened your bowels
  • Difficulty passing urine

Rare side effects

Fewer than 1 in 100 people have these.

  • Slowing of the heart beat or palpitations – tell your doctor or nurse as you may need a lower dose of diamorphine
  • A drop in blood pressure so that you feel faint when standing up
  • Slowed breathing – tell your doctor or nurse as you may need a lower dose
  • A flushed face

Important points to remember

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.

Other medicines and substances

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

It is important not to become pregnant while having diamorphine. There is a risk that the baby could become dependant on it and suffer from withdrawal symptoms after the birth. 


Don't breastfeed while having diamorphine because the drug may come through in the breast milk.

Addiction and diamorphine

Some people worry about becoming addicted to diamorphine. When you take this kind of drug to control pain, it is unlikely that you will become addicted. But talk to your doctor or specialist nurse if you are worried. 

Drowsiness and diamorphine

If you become drowsy after having diamorphine for a while, it may mean that you need to lower your dose. Talk to your doctor or nurse before you change your dose. It is important to let them know. It can be very harmful to just stop taking diamorphine. You are likely to need to slowly reduce the amount you take.


More information on diamorphine

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

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

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Updated: 6 October 2015