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Written by Healthwords's team of doctors and pharmacists based in UK | Updated: 26.01.2023 | 3 min read

Codeine is a medicine known as an opioid. It is a painkiller (also known as analgesic) and is used for the short-term treatment of pain in a range of conditions, including headaches, migraines, toothache, period pain and muscle pain. It can be used by adults and children ages 12 and over, and you can buy it from any pharmacy or your doctor can prescribe it.

Over-the-counter codeine comes in combination with other painkillers, namely ibuprofen, aspirin and paracetamol. You should only use this combination if these painkillers have not worked on their own. These codeine combination products are some of the strongest painkillers available over-the-counter and come as tablets, capsules or effervescent tablets (dissolve them in water before swallowing). You’ll need a prescription for higher strengths of codeine if your pain isn’t adequately under control.

Codeine is used for other ailments. Codeine Linctus is a syrup available over-the-counter to treat a dry, tickly cough and codeine is sometimes used to treat diarrhoea in specific circumstances.

How does it work?

Codeine helps treat pain by reducing the transmission of pain signals along nerves in the brain and spinal cord. Codeine may help relieve coughing by suppressing activity in the brain responsible for the normal cough reflex, although evidence for its effectiveness is limited. Codeine also slows down the movement of the intestines, which makes it effective at treating diarrhoea.

Can I become addicted to codeine?

Yes, it’s possible to become addicted to codeine if you take it for too long. It belongs to a family of drugs called opioids. Opioids activate receptors in the brain and spinal cord give us feelings of pain and pleasure. They block pain signals and release large amounts of dopamine, which can give us a good feeling, and we seek to repeat the experience. We also feel unwell without it. This is called dependency. It also carries the risk of tolerance with prolonged use, whereby you need to keep increasing the dose to have the same effect. Therefore, if you are taking codeine over the counter, you must not take it for more than three consecutive days. If you follow this guidance you are unlikely to experience any problems, so this shouldn’t cause undue concern.

Who should avoid codeine?

Do not take codeine if you have previously had an allergic reaction to codeine or another ingredient listed in the medication. Children under 12 years should not take codeine.

Speak with your doctor or pharmacist before taking codeine if you are pregnant or breastfeeding, if you have any medical conditions, or if you have past or current addiction to alcohol or drugs. You should avoid this is you’ve had an allergic reaction to another opioid in the past.

Codeine can interact with other medicines such as sleeping tablets and other medicines that can cause drowsiness. If you take any prescription, over-the-counter or herbal medicines, ask your doctor or pharmacist to check they are safe to take alongside codeine.

Are there any side-effects?

Common side effects can include constipation, drowsiness, headache, feeling sick, vomiting, dry mouth and sweating. If you experience drowsiness, it is best to avoid driving and drinking alcohol.

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