Diamorphine | Cancer Research UK
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This page tells you about the painkilling drug diamorphine and its side effects. You can read about


What diamorphine is

Diamorphine is a pain killing drug. It is a type of opioid.

You can only get diamorphine on prescription from your doctor. It is similar to the drug morphine. You have diamorphine 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. Diamorphine can also reduce breathlessness caused by a build up of fluid around the lung (a pleural effusion). 

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

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

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 your doctor or nurse know. It can be very harmful to just stop taking diamorphine. You are likely to need to slowly reduce the amount you take.


How you have diamorphine

Diamorphine is a white or off-white powder. A doctor or nurse dissolves it 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.


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 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 pain in your stomach – if you have pain and haven’t opened your bowels tell your doctor or nurse
  • 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

The side effects above may be mild or more severe. A side effect may get better or worse, or more side effects may develop while you are having diamorphine. 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

Coping with side effects

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.

Diamorphine may react with the following medicines or substances

  • Some anti depressant drugs
  • Some tranquillisers or sleeping tablets
  • Alcohol
  • Some medicines used to stop leakage of urine
  • Some medicines for Parkinsonism
  • Some anti sickness drugs
  • Some medicines that stimulate the digestive system
  • Some antibiotics
  • Some medicines for stomach ulcers and indigestion

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. 


It is not advisable to breastfeed while taking diamorphine because the drug can come through in the breast milk.


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 www.mhra.gov.uk.

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Updated: 17 September 2013