Like all medicines, codeine can cause side effects in some people. But many people have no side effects or only minor ones.
You have a higher chance of getting side effects if you take a higher dose of codeine.
Common side effects
There are things you can do to help with common side effects of codeine.
Constipation
Try to get more fibre into your diet, such as fresh fruit, vegetables and cereals. Try to exercise more regularly, for example by going for a daily walk or run.
If this does not help, talk to your pharmacist or GP.
Feeling or being sick (nausea or vomiting)
Take codeine with or just after a meal or snack to ease feelings of sickness. If you're being sick, try small frequent sips of water. This side effect should normally wear off after a few days. Talk to your GP about taking an anti-sickness medicine if it carries on for longer.
If you take the combined contraceptive pill or progestogen-only pill and you're vomiting, your contraception may not protect you from pregnancy. Check the pill packet to find out what to do.
Feeling sleepy
This side effect should go away within a few days as your body gets used to codeine. Talk to your GP if it carries on for longer.
If you're feeling sleepy:
- stop drinking alcohol while you're taking codeine
- do not drive, cycle or use tools or machinery
Confusion (unable to concentrate or think clearly, or having muddled thoughts)
This side effect should wear off within a few days as your body gets used to codeine. Talk to your GP if it carries on for longer.
Do not drive, cycle or use tools or machinery.
Feeling dizzy and vertigo
If codeine makes you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so that you do not faint, then sit until you feel better.
Do not stand up too quickly after you've been sitting or lying down. Do not drive, cycle or use tools or machines if you feel dizzy.
If the dizziness does not get better within 1 to 2 days, talk to your pharmacist or GP.
Dry mouth
Try chewing sugar-free gum or sucking sugar-free sweets.
Headaches
Rest and drink plenty of fluids. It's best not to drink alcohol. Ask your pharmacist to recommend a painkiller.
Talk to your GP if the headaches are severe, get worse or last longer than a week
Serious side effects
Serious side effects are rare. But they can happen.
Urgent advice: Contact your GP immediately if you:
- have muscle stiffness
- get symptoms of low blood pressure
Emergency action required: Call 112 or 999 or go to your nearest emergency department (ED) now if you have:
- difficulty breathing or short, shallow breathing
- a fit or seizure
- small pupils
Do not drive. Ask someone to drive you or call 999 and ask for an ambulance. Bring all the medicines you take with you.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to codeine.
Emergency action required: Call 112 or 999 or go to your nearest ED now if:
- your lips, mouth, throat or tongue start swelling
- you have trouble breathing or you're wheezing
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
Do not drive yourself. The person you speak to at 999 will give you advice about what to do.
Long-term side effects
Some people with long-term conditions may need to take codeine for a long time.
If you need to take it for a long time your body can become used to it. This is known as tolerance. This means you need higher doses to control your pain over time.
Some people can become more sensitive to pain (hyperalgesia). If this happens, your GP will reduce your dose gradually to help these symptoms.
It's possible to become addicted to codeine. For this reason, your dose will be reviewed to make sure you're only having the amount you need to control your pain.
If you're having treatment for cancer pain or other severe pain, your pain control will be carefully monitored.
Talk to a GP or pharmacist if you're worried about tolerance, hyperalgesia or becoming addicted.
Codeine dependence
If you're addicted to codeine, you may find it difficult to stop taking it or feel you need to take it more often than necessary.
If you stop taking codeine suddenly you may get withdrawal symptoms.
These can include:
- feeling agitated or anxious
- panic attacks
- feeling your heartbeat (palpitations)
- difficulty sleeping
- shaking
- sweating
- body aches
- feeling restless
Talk to your GP if you:
- are worried about addiction
- need help with addiction
- want to stop taking codeine
Non-urgent advice: Get help with problem drugs and alcohol use
Freephone 1800 459 459 for confidential advice
Other side effects
See the patient information leaflet that comes with your medicine for a full list of side effects.
Non-urgent advice: Find your patient information leaflet
Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.
Report side effects
You can report any suspected side effects to the Health Products Regulatory Authority (HPRA): report an issue - hpra.ie