Codeine is used for pain relief. Find out how to take it safely and possible side effects.
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|November 2020: Notification that codeine-containing medicines are now available on prescription only.|
|As of 5 November 2020, all codeine-containing medicines will be available on prescription only and can no longer be bought from your pharmacy without a prescription. Products affected include:
What is codeine?
Codeine is used for the relief of moderately severe pain, such as after an injury or operation. It's usually used when milder pain relief 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 codeine. Read more about pain, pain-relief medication and opioid painkillers.
Codeine can also be used to treat dry cough and diarrhoea.
Use in children and adolescents
New Zealand's Medsafe, a unit of the Ministry of Health, 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.
- Medsafe has advised that codeine should not be used in children younger than 12 years.
- In adolescents aged 12–18 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 is different for different people.
- Always take codeine exactly as your doctor has told you.
- Depending on the reason you are taking codeine, your doctor may advise you to take regular doses or take it only when you need it for relief. Make sure you know how you are to take it.
- 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 your 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 enough pain relief.
- Some other people break down codeine very quickly (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/Pākehā population may be poor or ultra-rapid metabolisers. The prevalence in Māori and Pasifika people is not known.
- If you are taking codeine for pain relief, and it doesn’t seem to be working, let your doctor know.
- If you are taking codeine and get side effects such as nausea, vomiting, constipation, lack of appetite, drowsiness or extreme sleepiness, let your doctor know. Other options may be better for you.
- If you have more severe side effects, such as difficulty waking, confusion or shallow breathing, let your doctor know straight away or call Healthline 0800 611 116.
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 sleepy, drowsy or dizzy.
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 (peeing)?
- 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, eg, constipated for more than a week?
- Do you 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.
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
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- Codeine may interact with a few medicines 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 (eg, Benadryl Dry Forte®, Duro-Tuss®)
- sedating antihistamines (eg, Phenergan®).
- Codeine New Zealand Formulary
- Opioid analgesics New Zealand Formulary
- Codeine – new restrictions on use in children and young adults Medsafe, 2018
- Helping patients cope with chronic non-malignant pain: it’s not about opioids BPAC, 2014
- Identifying and managing addiction to opioids BPAC, 2014