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

Type of medicine

Also called

  • Belongs to a group of medicines known as analgesics (pain killers)
  • Opioid pain reliever 
  • Codeine Phosphate®

What is codeine?

  • Codeine is an opioid painkiller (analgesic) used for the relief of pain.
  • It can also be used to treat cough and to relieve severe diarrhoea.
  • Codeine is commonly found in combination with other ingredients in pain relieverswhich you can buy without a prescription. Tell your doctor if you are already taking these. Examples of pain relievers that contain codeine:
    • Panadeine®
    • Codalgin®
    • Nurofen Plus®
    • Mersyndol®
    • Panafen Plus®


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

How to take codeine

  • Codeine is not affected by food so you can take it with or without food.
  • Limit or avoid drinking alcohol while your are taking codeine. Combining codeine 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, codeine 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
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Feeling sick or vomiting
  • Try taking codeine after meals.
  • Tell your doctor if this is troublesome
  • Constipation
  • Eat a diet rich in fibre and drink plenty of water.
  • Tell your doctor if troublesome.
  • Headache, dry mouth, altered vision, skin rash and itching
  • These are quite common when you first start taking codeine, and usually go away with time.
  • Tell your doctor if troublesome.
  • Breathing difficulties, changes to your heartbeat
  • Tell your doctor immediately or ring HealthLine


  • Codeine may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting codeine 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: Codeine Phosphate

New Zealand Formulary Patient Information: Codeine

Credits: Sandra Ponen, Pharmacist. Reviewed By: Dr J Bycroft. Health Navigator NZ