Quick answer
What is codeine used for?
Codeine is an opioid medicine used for pain and sometimes for cough, which the body converts into morphine with an effect that varies between people. It commonly causes constipation and drowsiness, so it is intended for short-term use only. It is not suitable for children under 12, and caution is needed when breastfeeding or driving.
How codeine works
Codeine is a prodrug, meaning it is converted into morphine in the liver to produce its pain-relieving effect. Genetic differences in the CYP2D6 liver enzyme mean this conversion — and so the effect of codeine — varies considerably between people.
What codeine is used for
Codeine is used for acute moderate pain, occasionally for diarrhoea, and to a limited extent for cough. It is generally considered a second-line option, used when simpler painkillers have not been sufficient.
Side effects of codeine
Common side effects include constipation, nausea, and sedation. Tolerance and dependence can develop with prolonged use, so codeine is best used for short periods.
Codeine safety precautions
Codeine should be avoided while breastfeeding, in children, and in people with severe asthma. It should also be stored safely and kept away from others.
Common questions about codeine
- What if codeine is not working for my pain?
- Some people are genetically poor metabolisers of codeine, meaning their body converts very little of it into morphine, so it has little effect. If this happens, a GP can suggest an alternative painkiller that will work better for you.
- Can codeine be taken with other opioids?
- Codeine should not be combined or "stacked" with other opioid painkillers, as this increases the risk of overdose. Always tell your GP or pharmacist about every pain medicine you are taking.
- What withdrawal effects can codeine cause?
- After prolonged use, stopping codeine can cause withdrawal symptoms such as irritability and restlessness. It should be tapered off gradually under medical guidance rather than stopped abruptly.
- Is codeine used in cough medicines?
- Codeine linctus is sometimes used for cough, though the evidence for its effectiveness is limited. Its use is restricted and only recommended for short courses.