Codeine

What is Codeine?

Codeine (codeine phosphate) is a mild opioid analgesic derived from the opium poppy. It is indicated for the short-term treatment of mild to moderate pain not adequately controlled by non-opioid analgesics, for the symptomatic relief of dry or irritating coughs, and for the short-term management of acute diarrhoea. Codeine is a prescription-only medicine in all EU member states.

How does Codeine work?

Codeine is a prodrug that is converted in the liver to morphine by the cytochrome P450 enzyme CYP2D6. The resulting morphine produces analgesic effects through the following mechanisms:

• Opioid receptor binding: Morphine (and to a lesser extent codeine itself) binds to mu-opioid receptors distributed throughout the central nervous system and peripheral tissues. This binding inhibits the transmission and perception of pain signals along ascending pain pathways.
• Antitussive action: Codeine acts on cough centres in the medulla oblongata, raising the threshold for the cough reflex and suppressing dry, nonproductive coughing.
• Antidiarrhoeal action: Opioid receptors in the gastrointestinal tract slow intestinal motility, reducing the frequency of bowel movements and increasing water absorption in the gut.
• Anxiolytic and sedative effects: Like other opioids, codeine produces mild sedation and anxiolysis, which can contribute to its perception as a pain reliever.

The degree of analgesic effect varies considerably between individuals depending on their CYP2D6 genotype. Poor metabolisers (approximately 7–10% of the European population) produce minimal morphine from codeine and experience reduced analgesia. Ultra-rapid metabolisers (approximately 1–3% of Europeans) produce excess morphine and are at risk of opioid toxicity even at standard doses.

Who is Codeine for?

Codeine is indicated for adults and adolescents aged 12 years and older (with restrictions in those under 18 who have undergone certain surgical procedures) for the following conditions:

• Mild to moderate pain: When paracetamol, ibuprofen, or other non-opioid analgesics have been insufficient. Examples include musculoskeletal pain, dental pain, headache, and post-traumatic pain.
• Dry, irritating cough: When non-opioid cough suppressants (such as dextromethorphan) have not provided adequate relief.
• Acute diarrhoea: Short-term symptomatic management of acute loose stools in adults.

Codeine is not appropriate for children under 12 years of age, patients under 18 who have undergone tonsillectomy or adenoidectomy, known ultra-rapid CYP2D6 metabolisers, breastfeeding mothers, or patients with significant respiratory depression, severe asthma, or paralytic ileus. A full medical assessment is required before any prescription is issued.

Dosage

Codeine phosphate is available in tablet and oral solution forms. Doses vary by indication:

Indication	Adult Dose	Frequency	Maximum Daily Dose
Pain	30–60 mg	Every 4 hours	240 mg/day
Cough	15–30 mg	Every 4–6 hours	120 mg/day
Diarrhoea	30 mg	Up to 4 times daily	120 mg/day

Codeine for pain should be used for no longer than 3 days. For cough, treatment should not typically exceed 5 days. If symptoms persist beyond these timeframes, patients should seek medical reassessment.

The lowest effective dose for the shortest duration should always be used. Patients should not adjust their dose without guidance from their prescribing doctor.

Side effects

As with all medicines, Codeine may cause side effects. The risks associated with opioid medicines require particular attention.

Common side effects (may affect up to 1 in 10 people)

• Constipation (very common with opioid use)
• Nausea and vomiting
• Drowsiness and sedation
• Dizziness and light-headedness
• Dry mouth
• Headache

Less common but serious side effects

• Dependence and withdrawal: Even short-term use of codeine can lead to physical dependence. Prolonged use or misuse significantly increases this risk. Abrupt discontinuation may cause withdrawal symptoms including restlessness, anxiety, muscle aches, and insomnia.
• Respiratory depression: Codeine can dangerously suppress breathing, particularly in ultra-rapid metabolisers, those with respiratory conditions, or when combined with other CNS depressants. This is a medical emergency.
• Neonatal opioid toxicity: Codeine is contraindicated during breastfeeding because morphine produced from codeine passes into breast milk and can cause serious harm — including fatal respiratory depression — in neonates.
• Serotonin syndrome: Risk exists when codeine is used concurrently with serotonergic agents such as SSRIs, SNRIs, triptans, or MAO inhibitors.
• Misuse and addiction: Codeine has a recognised potential for misuse and addiction, particularly in individuals with a personal or family history of substance use disorder.

This is not a complete list of side effects. Refer to the EMA-approved product information for full prescribing details.

How to get Codeine online in Europe

Codeine phosphate is a prescription-only medicine (POM) across all EU member states. It cannot be legally dispensed without a valid prescription from a licensed medical professional.

Prescrivia operates as a technology intermediary platform: we do not prescribe medicines, employ doctors, or sell medicines. Our platform connects patients with independent EU-registered doctors who can conduct confidential online health assessments.

The process works as follows:

1. Complete a health assessment: Answer a structured set of health questions covering your medical history, current medications, the nature and duration of your symptoms, and prior use of analgesics or opioid-containing medicines.
2. Doctor review: An independent EU-registered doctor reviews your assessment. If Codeine is clinically appropriate for your situation, they may issue a short-term prescription. If it is not appropriate, the doctor will recommend alternatives.
3. Prescription and fulfilment: If a prescription is issued, it is forwarded to a licensed EU pharmacy partner, which dispenses and ships the medicine directly to you.

Important: Prescrivia does not guarantee that a prescription will be issued. All prescribing decisions are made independently by qualified medical professionals based on your individual clinical circumstances.

Important safety information

Do not use Codeine if you:

• Are under 12 years of age
• Are under 18 and have had your tonsils or adenoids removed for sleep apnoea
• Are breastfeeding
• Are a known ultra-rapid CYP2D6 metaboliser
• Have significant respiratory depression, severe asthma, or chronic obstructive pulmonary disease
• Have paralytic ileus or acute inflammatory bowel conditions
• Are taking or have recently stopped taking MAO inhibitors (within 14 days)

Tell your doctor before starting Codeine if you have:

• A personal or family history of opioid dependence or substance misuse
• Liver or kidney disease
• Adrenal insufficiency (Addison’s disease)
• Hypothyroidism
• A history of head injury or raised intracranial pressure
• Enlarged prostate or urinary difficulties
• Gallbladder disease or biliary colic

Drug interactions: Codeine interacts with alcohol (increased CNS and respiratory depression), sedatives, benzodiazepines, antidepressants, antipsychotics, other opioids, and CYP2D6 inhibitors (such as bupropion, fluoxetine, paroxetine, which reduce codeine’s conversion to morphine). Always disclose all current medications to your doctor.

Sources

Medical information on this page is based on the following sources:

• European Medicines Agency (EMA). Codeine-containing medicinal products — Restricted indications, new contraindications and warnings. EMA/PRAC/384580/2013.
• European Medicines Agency (EMA). Questions and answers on the use of codeine for pain relief in children. Available at: ema.europa.eu
• World Health Organization (WHO). Codeine — Critical Review. Expert Committee on Drug Dependence.
• Derry S, et al. Single dose oral codeine, as a single agent, for acute postoperative pain in adults. Cochrane Database Syst Rev. 2010.

This content is reviewed periodically to reflect updated clinical guidance. It is provided for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for advice relevant to your individual health circumstances.