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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 (painkillers)
  • Opioid pain reliever 
  • Codeine Phosphate®
  • Panadeine
  • Panadeine Extra
  • Panadeine Plus 
  • Ibucode Plus®
  • Nurofen Plus®
  • Panafen Plus®  

Codeine is commonly used in combination with other ingredients in pain relievers which you can buy without a prescription. Examples of pain relievers that contain codeine:

  • codeine + paracetamol: Panadeine®, Panadeine Extra®, Panadeine Plus®
  • codeine + ibuprofen: Nurofen Plus®, Panafen Plus®, Ibucode Plus®

Tell your doctor or pharmacist if you are already taking these.

What is codeine?

Codeine is used for the relief of moderately severe pain such as after an injury, or operation. It is usually used when other milder painkillers such as paracetamol or non-steroidal anti-inflammatories (NSAIDs) don’t work well enough. Codeine belongs to a group of medicines called opioid painkillers. They act on your brain and nervous system to lessen the way you feel pain. Other pain relievers such as paracetamol and NSAIDs (ibuprofen, diclofenac, naproxen) may also be used with codeineRead more about painpain-relief medication and opioid painkillers.

Codeine can also be used to treat dry cough and diarrhoea.

Use in children and adolescents

Medsafe, a unit of the Ministry of Health, New Zealand, has assessed the safety and effectiveness of codeine in children and adolescents. Codeine can cause serious breathing problems in children that could result in death. 

  • They have advised that codeine should not be used in children younger than 12 years.
  • In adolescents 12 to 18 years, codeine should not be used for pain after surgery to remove tonsils or adenoids, for relief of cough, or in people who have breathing problems.


  • The dose of codeine will be different for different people. 
  • Always take your codeine exactly as your doctor has told you. Depending on the reason you are taking it, your doctor may advise that you take regular doses or take codeine only when you need it for relief. Make sure you know which is right for you.
  • The pharmacy label on your medicine will tell you how much codeine to take, how often to take it, and any special instructions.

Variations in response to codeine

Codeine is broken down in the liver to morphine, which is a strong pain reliever. People may respond differently to codeine depending on how their liver breaks down codeine.

  • Some people are poor metabolisers, which means that they are unable to convert codeine to morphine, and don't get adequate pain relief.
  • On the other hand, some people break down codeine very rapidly (ultra-rapid metabolisers) and are at increased risk of developing side effects, even at low doses.
  • Estimates suggest that up to 10% of the European population may be poor or ultra-rapid metabolisers. The prevalence in Maori and Pacific people is not known.
  • If you are taking codeine for pain relief, and it doesn’t seem to be working, let your doctor know. Alternatively, if you are taking codeine and you get side effects such as nausea, vomiting, constipation, lack of appetite, drowsiness, extreme sleepiness, difficulty waking, confusion or shallow breathing, let your doctor know. Other options may be better for you.

How to take codeine

  • You can take codeine with or without food.
  • Stop taking codeine if your symptoms are relieved. 
  • Limit or avoid drinking alcohol while you 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. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Precautions – before starting codeine

  • Are you pregnant or breastfeeding?
  • Do you have problems with your liver or your kidneys?
  • Do you have problems with your prostate or any difficulties passing urine?
  • Do you have any breathing problems, such as asthma or chronic obstructive pulmonary disease (COPD)?
  • Have you had a recent head injury?
  • Do you suffer from constipation - have been constipated for more than a week or have an inflammatory bowel problem?
  • Have you ever been dependent on drugs or alcohol?

If so, it’s important that you tell your doctor or pharmacist before you start codeine. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Possible side effects

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


Addiction is an excessive craving. If you are addicted to codeine, it means you are not able to control your use of it. It is unusual for people who are prescribed codeine for short periods of time to become addicted to it. Some people are more likely to develop addiction than others - you may be at risk for addiction if you have mental health problems such as depression or a history of substance abuse, including alcohol and recreational drugs.

To reduce your risk of addiction, codeine should be used for the shortest possible time, at the lowest effective dose, with a plan in place to reduce and withdraw treatment.

Other side effects

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
  • 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.
  • 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

Codeine SafeRx, Waitematā DHB
Codeine Phosphate Medsafe Consumer Information
Codeine New Zealand Formulary Patient Information


  1. Codeine New Zealand Formulary
  2. Opioid analgesics New Zealand Formulary
  3. Codeine – new restrictions on use in children and young adults Medsafe, 2018
  4. Helping patients cope with chronic non-malignant pain: it’s not about opioids BPAC, 2014
  5. Identifying and managing addiction to opioids  BPAC, 2014
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 15 May 2019