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What is Codeine?

In 2021, there were 200 cases of recorded deaths from codeine drug poisoning in England and Wales, which is more than twice the number of deaths recorded just a decade ago. According to the Priory Group, 5 out of the 115,000 prescriptions given for opioids each day in the UK lead to death.

Measures are being taken to reduce the rising levels of opioid addiction in the UK, but with the rise in chronic pain conditions, many people are finding themselves dependent upon codeine in its different forms, developing a silent and hidden addiction to the substance.

What is codeine?

Codeine, known pharmaceutically as 3-methylmorphine, is a painkiller that is usually used to treat short-term pain as well as coughs and diarrhoea, deriving from the opioid family of drugs. Opioids are drugs that come from the poppy plant, or are synthetically engineered to mimic the sedative effects of the poppy plant.

The poppy has been used for thousands of years as a medicinal remedy for pain. When the unripened seed of a poppy is cut, a fluid known as ‘milk of the poppy’ is released. The alkaloids found in the milk of the poppy are morphine, codeine and papaverine. Codeine was discovered by French chemist Pierre Jean Robiquet in 1832 when he was trying to find more efficient ways to extract morphine.

Opioids have been used pharmaceutically for a long time to treat pain, in weakened forms, and often combined with paracetamol to make them more effective. Pharmaceutical codeine, when ingested, is converted into morphine in the body, by way of the liver enzyme CYP2D6 which metabolises different drugs. Up to 70% of codeine is converted into codeine-6-glucuronide, up to 15% is converted into norcodeine and the rest is converted to morphine.

Codeine functions by attaching to the proteins in the nerve cells called opioid receptors. By doing this, it blocks the release of neurotransmitters, the pain signals sent by the body to the brain, reducing the feeling of pain in the body.

Codeine also suppresses the part of the brain that is responsible for coughing, hence it will be prescribed by a doctor if the patient has a persistent dry cough. Codeine is also a narcotic analgesic drug, which is a drug that possesses numbing and paralysing properties.

Prescribing codeine for dry cough

Can codeine be addictive?

Codeine, whilst it is isolated from morphine, its potent counterpart from which it’s derived, is still highly addictive. It possesses many of the same qualities as morphine, though it is far less potent as a sedative and analgesic drug.

Codeine can give users a sensation of feeling ‘high’. This euphoric feeling, combined with the absence of pain, can cause a user to become addicted to this feeling, particularly if they are typically depressed or mentally unstable.

Whilst this drug is usually prescribed for short-term use only, there are many instances where long-term use is authorised by a GP, and people can ingest codeine on a regular basis. This can cause them to build a tolerance to the drug, causing them to take more, or seek out a stronger opioid, such as morphine, or even heroin.

Codeine is not advised as a treatment for chronic pain, but as the rates of chronic pain in the UK are at an all-time high, with an estimation of at least 34% of the population in England suffering from some kind of chronic pain condition, and 26% in the UK overall (Ipsos), codeine is often turned to as a way of managing pain.

In July 2005, manufacturers of codeine purchased over the counter agreed that the number of pills containing codeine in a pack should be limited to 32. Furthermore, co-codamol above the strength of 8mg/500mg can only be prescribed by a doctor.

Limitations on the number of painkillers you can buy in any one transaction are not limited to codeine, but other painkillers such as ibuprofen and paracetamol are.

What is codeine used for?

Codeine is used as a painkiller to treat pain when less potent painkillers, such as ibuprofen, paracetamol and aspirin, are not effective.

It may be administered in the following situations:

  • Following an operation.
  • After an injury.
  • To suppress dry coughs.
  • To treat diarrhoea.
  • For ongoing pain, such as cancer pain.

Codeine can be given in different forms, depending upon what it is needed for. It is usually given in the following formats: pills, liquids, syrups or injections, and taken every 4 hours. Codeine will only be injected in hospital, and is usually for quick administration, where pain is severe.

The maximum dose of codeine daily is 240mg. Codeine will start working after half an hour, and will reach its maximum efficacy 2 hours after ingestion, with its effects spanning between 4 and 6 hours.

How is codeine abused?

Many people are addicted to codeine without realising, due to its habit-forming properties. In recent years, the prevalence of codeine addictions has seen cough syrups that contain the drug being removed from pharmacies. Co-codamol is still available to purchase in pharmacies in the UK at a reduced dosage of 8mg/500mg per pill.

The MHRA is keeping the potential for codeine to be removed from over-the-counter sales under review, making it available under prescription only. However, this proposition has been under scrutiny as it may increase GP workload, through patients who perceive that they are in need of codeine coming into the practice for a prescription instead of a pharmacy.

Codeine prescriptions are not as limited for codeine as they are for drugs like morphine, so it can be easier to obtain. Despite GPs being instructed to never suggest codeine as a painkiller for patients with chronic pain, this guideline isn’t always adhered to. Abuse usually starts after an injury, operation or instance of pain, where the patient becomes addicted to the feelings of relaxation, drowsiness, euphoria, pain relief and indifference it can induce.

As codeine is an opiate, your body can develop a tolerance to it, as the pain receptors in your body need more and more to prohibit their function. Thus, the dosage that an individual takes at the beginning will not be as effective as they continue to use codeine.

Opioid tolerance is dangerous as it can lead to dependence, meaning that users need codeine to cope with their pain, physically and emotionally. Codeine is intended for short-term use, and never for use for longer than 3 days, unless under the guidance of a doctor.

Some people take codeine together with other substances, such as alcohol, which causes excessive sleepiness, and could lead to shortness of breath and respiratory failure, a coma and death. Codeine is used recreationally in a liquid form, known colloquially as ‘purple drank’, ‘sizzurp’, ‘lean’, ‘cough syrup’, ‘syrup’, ‘captain Cody’ and ‘schoolboy’ amongst other names. This is made by combining codeine cough syrup with fizzy drinks, such as Sprite. This is done so that the codeine can be consumed in large quantities.

Additionally, there is a large and profitable illegal drug trade for opioids, with Afghanistan being the largest exporter and producer of opioids in the world, as found by the UN Office on Drugs and Crime, and accounting for up to 85% of the illicit global supply of opioids.

The dark web has made it quite straightforward for some people to obtain codeine illegally, with no limitation on how much one can order, which can make it easy for an addiction to become fatal. Some people also abuse codeine by using somebody else’s prescription.

Recovery from operation

How does codeine affect the body?

Codeine taken in appropriate doses, as prescribed, has the following effects on the body:

  • Constipation.
  • Nausea.
  • Dryness in the mouth.
  • Headaches.
  • Dizziness.
  • Vertigo.
  • Confusion.
  • Sleepiness.

Other, more rare side effects include:

  • Difficulty breathing, slow and shallow breaths.
  • Muscle stiffness.
  • Low blood pressure.
  • Feeling faint.
  • Quickened heartbeat.

People who have prolonged use of codeine may have withdrawal symptoms, such as:

  • Sleeplessness.
  • Irritability.
  • Anxiety.
  • Headaches.
  • Heart palpitations.
  • Sweating.
  • Clammy skin.
  • Slurred speech.

What are the risks of codeine?

There are risks associated with using codeine for longer than has been advised by a doctor.

These include but are not limited to:

  • Pancreatitis. This is not common, nevertheless, there is a strong link between codeine triggering spasms in the pancreas.
  • Liver damage. The liver breaks down enzymes in codeine, converting them to morphine, hence, it can undergo damage.
  • Kidney damage. Codeine drugs that contain medicines such as acetaminophen or aspirin are most harmful to the kidneys.
  • Increased sensitivity to pain. Whilst codeine works to block pain transmitters, the body can counteract this by producing more receptors so that the pain signal can be sent. Thus, the user can become more sensitive to pain.
  • Depression. Whilst codeine may temporarily relieve anxiety or depression, long-term abuse of the drug can make mental health conditions worse, as the user becomes dependent.
  • Respiratory depression. Opioid-induced respiratory depression (OIRD) is a life-threatening condition, usually caused by ingesting large amounts of codeine, or from complications involving anaesthesia after operations.
  • Reduced muscle tone. Caused by relaxing the contraction of your muscles, users may find it harder to exercise, decreasing their muscle tone over time.
  • Gut and digestion issues. 90% of people who are prescribed an opioid for long-term use, mostly for cancer pain, become constipated. This is because gut movement is slowed down and the digestive tract muscles become tighter.

Many people who are addicted to codeine have an underlying health condition, either physical or mental, or both. They may have had these prior to their dependence on codeine, or developed them since their dependence.

These include:

  • Bipolar disorder.
  • Alcohol addiction.
  • Depression.
  • Schizophrenia.
  • Chronic pain.
  • Anxiety.

Short-term and long-term effects of codeine

There are social and economic side effects of codeine abuse. Abusing codeine, or any addictive substance, can cause other elements of your life to descend into chaos.

Long-term abusers of codeine may find themselves:

  • Homeless.
  • Losing their job.
  • Victims of perpetrators of domestic abuse.
  • Involved in crime.
Long term abuser of codeine

What are the different forms of codeine?

The following are common combinations prescribed by doctors:

  • Co-codamol (Codeine and Paracetamol).
  • Co-dydramol (Codeine and Dyhydrocodeine).
  • Tramacet (Codeine and Tramadol).

Other opioids that may prescribed are:

  • Morphine.
  • Diamorphine.
  • Oxycodone.
  • Hydromorphone.
  • Buprenorphine.
  • Fentanyl.
  • Tapentadol.

How can someone with a codeine addiction be supported?

A study undertaken in 2017 found that people who were dependent upon codeine were likely to turn to the internet for help to control their use of the drug rather than to their GP or a medical professional. This can be attributed to many factors, including poor treatments for addictions, comfort in finding a community of people in similar situations online or fear of judgement.

Opioid replacement therapy (ORT), also known as substitution therapy, is a well-known form of treatment for those living with a considerable addiction to opioids. This therapy works by replacing the drug that the user is addicted to with a drug or dose that is prescribed.

This reduces risk-taking behaviours such as injecting, and decreases the risk of overdose. It is thought to be effective if it is adhered to, taking up to 4 to 12 weeks for dependency to disappear. Drugs such as methadone hydrochloride and buprenorphine are used in opioid substitution therapy.

The following organisations could be helpful for anyone who needs support, advice and more information about using codeine:

  • Guts UK is a charity that supports research into the digestive system, including how opioids can cause constipation and other digestive symptoms.
  • The Forward Trust is a charity that helps to support and advise people who may have an addiction to substances. They offer different services such as employment, housing and mental health services, through their Taking Action on Addiction campaign supported by HRH Princess of Wales.
  • Pain UK provides support and advice to those living with long-term pain, some of whom may also be at risk from becoming addicted to codeine.
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About the author

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Rose Winter

Rose is a qualified teacher with six years of experience teaching in secondary schools and sixth forms across London. Before this, she worked as a communications officer in the Cabinet Office. Outside of work, Rose can be found researching topics of interest and spending time abroad.



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