Sounds like 'mor-feen'

Easy-to-read medicine information about morphine – what it is, how to take morphine safely and possible side effects.

Type of medicine Also called
  • Belongs to a group of medicines known as analgesics (pain killers) 
  • Opioid pain reliever
  • RA-Morph®
  • m-Eslon SR®
  • Sevredol®
  • LA-Morph®
  • Arrow-Morphine LA®

What is morphine?

  • Morphine is an opioid painkiller used for the relief of severe or strong pain such as after an injury, operation or for cancer.  
  • Morphine works on your brain and nervous system to lessen the way you feel pain.
  • It works best if you use it when the first signs of pain occur. If you wait until the pain has worsened, morphine may not work as well.
  • Other pain relievers (such as paracetamol, ibuprofen) may also be prescribed with morphine.


  • The dose of morphine will be different for different people.
  • Always take your morphine exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much morphine to take, how often to take it, and any special instructions.

How to take morphine

  • Morphine is not affected by food so you can take it with or without food.
  • Morphine is available in a range of formulations such as tablets, capsules, liquid, suppositories, and injection. Some formulations are short-acting or immediate release and others are long-acting or slow release. Ask your pharmacist if you are not sure about the formulation you are taking.  
  • The long-acting formulation must be swallowed whole. Do not crush or chew. This will release all the medication at once and cause side effects. 
  • Limit or avoid drinking alcohol while your are taking morphine. Combining morphine with alcohol can make you more sleepy, drowsy or dizzy.
  • If you forget to take your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the amount.

Possible side effects

Like all medicines, morphine can cause unwanted side effects, although not everyone gets them. Often unwanted side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Feeling sleepy, dizzy or tired
  • Reduced concentration
  • This is common when starting morphine or after increasing the dose.
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Feeling sick (nausea) or vomiting
  • This common in the first week to ten days of treatment.
  • Mostly this settles and goes away.
  • Tell your doctor if this is troublesome. You may need an anti-sickness tablet at times.
  • Constipation
  • Constipation is very common. 
  • Ask your doctor to prescribe a suitable laxative, which you need to take on a regular basis.
  • You also need to eat more fruit, vegetables, brown bread, bran based breakfast cereals and drink plenty of water.
  • Headache, dry mouth, altered vision, skin rash and itching
  • These are quite common when you first start taking morphine, and usually go away with time.
  • Tell your doctor if troublesome.
  • Breathing difficulties, slow or irregular breathing 
  • Tell your doctor immediately or ring HealthLine


  • Morphine may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting morphine or before starting any new medicines.
  • It may interact with medicines available without a prescription such as:
    • cough suppressants (such as Benadryl Dry Forte®, Duro-Tuss®)
    • sedating antihistamines (such as Phenergan®)

Learn more

Medsafe Consumer Information Sheet:

Arrow-Morphine LA

New Zealand Formulary Patient Information:

morphine (short acting)

morphine (long acting)

Credits: Sandra Ponen, Pharmacist.