Codeine at a glance
Medicine class
Opioid analgesic and cough suppressant.
Available forms
The selected products are an oral tablet and a linctus taken by mouth.
Food
Codeine tablets can be taken with or without food.
Driving
Codeine can cause sleepiness, confusion or visual disturbance. Do not drive or use machinery if affected.
Dependence
Repeated use can cause tolerance, dependence and addiction, even when used as prescribed.
What is Codeine used for?
Licensed uses among the selected UK products include:
Acute moderate pain in people older than 12 years when paracetamol or ibuprofen alone is not expected to provide adequate relief.
Dry or painful cough; the linctus is specifically licensed for non-productive cough.
Diarrhoea in adults, for the selected tablet product.
How does Codeine work?
Codeine has weak direct opioid activity and is partly converted by CYP2D6 into morphine, which provides much of its pain-relieving effect. It centrally suppresses the cough reflex. Genetic differences mean some people obtain little effect, while others produce morphine rapidly and have a greater toxicity risk.
Codeine preparations and strengths
Tablet
Route: Oral
Strengths: 15 mg, 30 mg, 60 mg
How to take Codeine
Follow the prescription label and product leaflet. Do not take extra codeine, combine it with another opioid-containing medicine without professional advice, or share it.
Swallow tablets whole with water, with or without food.
Measure liquid codeine using the supplied medicine measure, not a household spoon.
Avoid alcohol because it can increase sedation, low blood pressure and breathing problems.
If used regularly, seek advice before stopping because gradual withdrawal may be needed.
Codeine side effects
Common or expected effects
- Constipation
- Feeling or being sick
- Sleepiness or tiredness
- Dizziness
- Sweating
Get urgent medical advice
- Slow, weak or shallow breathing
- Extreme sleepiness, confusion, reduced consciousness or inability to wake
- Severe allergic reaction with swelling or breathing difficulty
- Blue or purple lips or fingernails
- Severe dizziness, faintness or symptoms of marked low blood pressure
Codeine in pregnancy
Use during pregnancy only after a prescriber assesses the benefits and risks. Most exposed pregnancies do not appear to have long-term problems, but possible links with some birth defects remain uncertain. Regular use may cause neonatal dependence and withdrawal, while use around labour may suppress the newborn's breathing.
Codeine while breastfeeding
Codeine should not be used while breastfeeding. Unpredictable conversion to morphine can expose the baby through breast milk, causing sleepiness, poor feeding, apnoea or respiratory depression. If taken accidentally, stop taking it and promptly seek professional advice, especially if the baby has these symptoms.
Codeine interactions
Check all prescribed, non-prescribed and recreational substances before using codeine. Important examples include:
Alcohol
May substantially increase sleepiness, low blood pressure and respiratory depression.
Benzodiazepines, sleeping medicines and other sedatives
Can cause profound sedation and breathing difficulty.
Common questions about Codeine
Answers are fully visible for fast scanning and source review.
Why does codeine work better for some people than others?
CYP2D6 converts codeine into morphine. People with low enzyme activity may obtain little benefit, while ultra-rapid metabolisers can produce excessive morphine and develop serious toxicity.
Can codeine make me sleepy?
Yes. Sleepiness, tiredness and dizziness are common. Avoid driving, cycling or using machinery until you know how it affects you.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.