How does morphine work?
Morphine is from a group of medicines called opiates, or narcotics.
It works in the central nervous system and the brain to block pain signals to the rest of the body. It also reduces the anxiety and stress caused by pain.
When morphine blocks the pain, there are other unwanted effects, for example, slow or shallow breathing. It also slows down digestion, which is why morphine can cause constipation.
How long will it take to work?
This depends on the type of morphine you take.
A morphine injection into a vein gives the quickest pain relief. It works almost straight away.
Morphine tablets and liquid work in 30 to 60 minutes but wear off after 4 to 6 hours.
Slow-release morphine can take a day or two to start working but the pain relief will last for longer.
How will it make me feel?
When you first take morphine, you might feel sleepy or sick. But this side effect will wear off after a few days as your body gets used to the medicine.
You might also notice you are less alert. Do not drive, cycle or operate machinery if you feel sleepy or less alert.
Are there any long-term side effects?
Some people with conditions that need long-term pain relief may need to take morphine for a long time.
If you need to take it for a long time your body can become used to it (known as tolerance). That means you need higher doses to control your pain over time.
Some people can become more sensitive to pain (hyperalgesia). If this happens, your doctor will reduce your dose gradually to help these symptoms.
It's possible to become addicted to morphine. For this reason, your dose will be reviewed to make sure you're only having the amount you need to control your pain.
Your treatment plan may include details of how and when you'll stop morphine.
If you're having treatment for cancer pain or other severe pain, your pain control will be carefully monitored. Speak to your doctor if you're worried about tolerance, hyperalgesia or becoming addicted.
How will I know if I'm addicted?
If you're addicted to morphine, you may find it difficult to stop taking it or feel you need to take it more often than necessary.
If you stop taking morphine suddenly you may get withdrawal symptoms.
These can include:
- feeling agitated or anxious
- panic attacks
- feeling your heartbeat (palpitations)
- difficulty sleeping
- shaking
- sweating
- body aches
- feeling restless
Talk to your doctor if you:
- are worried about addiction
- need help with addiction
- want to stop taking morphine
Is morphine a controlled medicine?
Morphine is a controlled medicine. This means there are strict rules on how it's prescribed and dispensed to make sure it's not given to the wrong person or misused.
When you collect morphine your pharmacist will ask for proof of your identity such as your passport or driving licence. You'll also be asked to sign the back of your prescription, to confirm that you've received it.
If you're collecting morphine for someone else, you're legally required to show the pharmacist proof of your identity if asked.
How can I tell what type of morphine I'm taking?
Ask your doctor or pharmacist if you're not sure what type of morphine you're taking.
Standard tablets are known by the brand name Sevredol.
Slow-release tablets are also known as MST Continus or Morphgesic SR. Slow-release capsules are also known as MXL or Zomorph.
Are there other painkillers I can try?
The type of painkiller that's best for you depends on what type of pain you have and the cause of your pain.
If morphine does not get rid of your pain or it becomes less effective, discuss this with your doctor.
Is morphine only used at the end of life?
Morphine is not only used at the end of a terminal illness. It's the amount of pain you have, not the stage of your illness, that decides whether morphine is prescribed for you.
Will it affect my contraception?
Morphine does not affect any type of contraception including the combined pill, progestogen-only pill or emergency contraception.
But if morphine makes you sick (vomit), your contraceptive pill may not protect you from pregnancy. If this happens, follow the instructions in the leaflet that comes with your contraceptive pill.
Find out more:
Can I drive or ride a bike?
Do not drive a car or ride a bike if morphine makes you sleepy, gives you blurred vision or makes you feel dizzy, clumsy or unable to concentrate or make decisions. This may be more likely when you first start taking morphine but could happen at any time, for example, when starting another medicine.
It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.
Even if your ability to drive is not affected, the police have the right to request a saliva sample to check how much morphine is in your body.
Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking morphine.
Can I drink alcohol with it?
It may be best not to drink alcohol while taking morphine as it may make you feel more sleepy or increase the risk of serious side effects.
It's best to stop drinking alcohol during the first few days of treatment until you see how the morphine affects you.
If you feel sleepy with morphine, stop drinking alcohol while you are taking it.
Will recreational drugs affect it?
If you take recreational drugs, such as cannabis, cocaine or heroin, while you're taking morphine, you're more likely to get the serious side effects of morphine including breathing difficulties, heart problems such as high blood pressure, seizures or fits and even going into a coma.
Some recreational drugs, such as cannabis, will also increase morphine side effects such as sleepiness and dizziness.
Taking heroin while you're on prescribed morphine is especially dangerous. You're more likely to get all the side effects of morphine, including addiction.
Tell your doctor if you think you may take recreational drugs while you're on morphine.
You can read more about the side effects of some recreational drugs on the Frank website.