Cancer drugs A to Z list
Diamorphine can also reduce breathlessness caused by a build up of fluid in the lungs.
You can only get diamorphine on prescription from your doctor. It is a type of opioid.
Read more about the different types of painkillers
Diamorphine is an opioid. Opioids are strong drugs similar to natural pain killing substances made in our body called endorphins.
Opioids block pain messages from travelling along the nerves to the brain.
You have diamorphine as an injection. This can be:
as an injection under your skin
into your bloodstream
as an injection into your muscle
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 diamorphine through a small needle put 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.
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
Find out more about central lines, PICC lines and portacaths
You have the injection into a muscle, usually into your buttock or upper thigh.
You usually have diamorphine every 4 hours, unless you have it as part of a syringe driver.
Your doctor will prescribe the dose that’s best to control your pain.
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 diamorphine 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.
Side effects can vary from person to person. They also depend on what other treatment you are having.
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
We haven't listed all the side effects here. Talk to your healthcare team if you have any new symptoms that you think might be a side effect of your treatment.
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.
You might have one or more of these side effects. They include:
This drug may make you feel drowsy. Don’t drive or operate machinery if you have this.
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.
Feeling or being sick is usually well controlled with anti sickness medicines. It might help to avoid fatty or fried foods, eat small meals and snacks and take regular sips of water. Relaxation techniques might also help.
It is important to take anti sickness medicines as prescribed even if you don’t feel sick. It is easier to prevent sickness rather than treat it once it has started.
is easier to sort out if you treat it early. Drink plenty 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 give you a laxative if needed.
Let your doctor or nurse know if you are sweating more than normal. Cutting out caffeine, nicotine and alcohol, and sipping cold or iced drinks may help to reduce sweating.
You may have difficulty breathing. If this happens, let your doctor or nurse know straight away.
A small number of people have an allergic reaction while having diamorphine as a drip into the bloodstream (intravenously). Tell your doctor or nurse immediately if you have shortness of breath, shock, low blood pressure, redness or swelling of the face, feeling hot, dizziness or a sudden need to pass urine. You should not be given anymore diamorphine if this happens.
You might feel muddled or forgetful. This is also called brain fog or mental clouding. Speak to your healthcare team if this is a problem for you.
This may happen with large doses of diamorphine.
This drug might make you feel dizzy. Don’t drive or operate machinery if you have this.
Mood changes can include feeling very sad or very happy. Tell your doctor or nurse if you’re having mood changes. They can arrange for you to talk to someone and give treatment if necessary.
Seeing or hearing things that are not there (hallucinations) can occur with this treatment. Speak to your doctor if this happens to you.
The pupils (black part) in your eyes may become narrower or look smaller.
You may get blurred or double vision. Do not drive or operate machinery if you have this symptom and speak to your doctor.
You might find it hard to pass urine. Let your doctor or nurse know if that happens.
Your blood pressure might drop when you stand up or change position suddenly. This is called postural hypotension. This may cause you to feel light headed or dizzy.
The skin of your face may look red (flushed).
You may feel as though the room is spinning. This is called vertigo. Let your doctor or nurse know if this happens.
Mood changes can include feeling very sad or very happy. Tell your doctor or nurse if you’re having mood changes. They can arrange for you to talk to someone and give treatment if necessary.
A dry mouth is also called xerostomia. Talk to your nurse or doctor if you have a dry mouth. They can give you artificial saliva to help with this. It can also help to drink plenty of fluids during treatment with diamorphine.
Skin problems include a skin rash, dry skin and itching. This usually goes back to normal when your treatment finishes. Your healthcare team can tell you what products you can use on your skin to help.
Tell your doctor or nurse if you keep getting headaches.
You may have less interest in sex, especially if you have diamorphine for a long period of time.
Seeing or hearing things that are not there (hallucinations) can occur with this treatment. Speak to your doctor if this happens to you.
These include changes in your heart rhythm such as a slow heartbeat or palpitations. Tell your doctor or nurse straight away if you have any heart problems.
You might have pain in the right side of your abdomen, particularly after eating a meal. This may spread towards your right shoulder.
We have more information about side effects and tips on how to cope with them.
Read more about how to cope with side effects
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.
It is important not to become pregnant while having diamorphine. There is a risk that the baby could become dependent on it and suffer from withdrawal symptoms after birth.
Talk to your doctor or nurse about effective contraception.
Don’t breastfeed during this treatment because the drug may come through into your breast milk.
People taking diamorphine for weeks or months can develop a physical dependence. This causes withdrawal symptoms if diamorphine is stopped.
Your doctor or nurse will advise you how to reduce the diamorphine dose gradually if necessary. Don't stop taking diamorphine suddenly.
Some people can also develop a psychological dependence (addiction) to diamorphine. 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 diamorphine
If you are having tests or treatment for anything else, always mention your cancer treatment. For example, if you are visiting your dentist.
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 and Healthcare products Regulatory Agency (MHRA) as part of their Yellow Card Scheme.
Last reviewed: 04 Nov 2025
Next review due: 04 Nov 2028
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Not all cancers cause pain and it can affect you in different ways. If you have pain, it is important to tell your doctor or nurse so it can be managed.
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Cancer drugs have side effects and these can vary from person to person. But there are things that you can do to help you cope.
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