Codeine

1. Introduction

Codeine is an opioid analgesic used to manage mild to moderate pain, cough suppression, and, in some cases, diarrhoea. It is metabolised in the liver to morphine, its active form, which binds to opioid receptors to reduce pain and suppress cough. However, due to its potential for dependence and abuse, its use is carefully controlled.

2. Indications

  • Approved Indications:
    • Mild to moderate pain relief.
    • Dry, unproductive cough (antitussive).
    • Diarrhoea (as part of combination therapy).
  • Off-Label Uses:
    • Pain management in specific post-surgical scenarios where non-opioids are insufficient.

3. Dosage

  • Adults:
    • Pain relief: 30–60 mg every 4–6 hours as needed (maximum 240 mg/day).
    • Cough suppression: 10–20 mg every 4–6 hours (maximum 120 mg/day).
  • Children:
    • Pain relief (only for children over 12 years): 0.5–1 mg/kg every 4–6 hours (maximum 240 mg/day).
    • Cough suppression: Not recommended in children under 18 years.
  • Elderly:
    • Start with lower doses due to increased sensitivity and adjust based on response.

4. Administration

  • Take orally with or after food to reduce gastrointestinal discomfort.
  • Avoid alcohol or other sedatives while taking codeine.

5. Forms Available

  • Tablets: 15 mg, 30 mg, 60 mg.
  • Syrup: Codeine phosphate 15 mg/5 mL.
  • Combination products: Codeine with paracetamol or ibuprofen (e.g., co-codamol).

6. Side Effects

6.1. Common Side Effects

  • Drowsiness.
  • Nausea and vomiting.
  • Constipation.
  • Dizziness.

6.2. Less Common Side Effects

  • Dry mouth.
  • Sweating.
  • Itching.

6.3. Rare but Serious Side Effects

  • Respiratory depression.
  • Dependence and withdrawal symptoms.
  • Severe allergic reactions (e.g., rash, difficulty breathing).

7. Warnings

  • Avoid in patients with respiratory depression or severe asthma.
  • Use cautiously in patients with head injury, as codeine can increase intracranial pressure.
  • Not recommended for use in children under 12 years for pain or under 18 years for cough suppression due to the risk of respiratory depression.

8. Precautions

  • Use with caution in patients with a history of substance abuse or dependence.
  • Avoid prolonged use to minimise the risk of addiction.
  • Use cautiously in patients with liver or kidney dysfunction, as drug metabolism and clearance may be impaired.

9. Interactions

  • Drug-Drug Interactions:
    • CNS depressants (e.g., benzodiazepines, alcohol): Increased risk of sedation and respiratory depression.
    • Monoamine oxidase inhibitors (MAOIs): May cause severe reactions.
    • CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): May reduce codeine’s efficacy by impairing its conversion to morphine.
  • Drug-Food Interactions:
    • Avoid alcohol, as it enhances CNS depressant effects.

10. Monitoring Parameters

  • Pain relief and reduction in cough symptoms.
  • Signs of respiratory depression, especially at higher doses.
  • Monitor for signs of dependence or misuse.

11. Use in Children

  • Not recommended for children under 12 years due to the risk of respiratory depression.
  • Use cautiously in children aged 12–18 years and only for short-term pain relief.

12. Use in Pregnancy

  • Category C: May cause neonatal respiratory depression or withdrawal if used during labour or long-term in pregnancy. Use only if benefits outweigh risks.

13. Use in Elderly

  • Use with caution due to increased sensitivity to side effects such as sedation, confusion, and constipation. Start at the lowest effective dose.

14. Use in Kidney Disease

  • Use cautiously in patients with severe renal impairment, as accumulation of active metabolites may increase the risk of toxicity.

15. Use in Liver Disease

  • Use with caution in patients with liver dysfunction, as metabolism may be impaired, increasing the risk of toxicity.

16. Patient Counselling Points

  • Take codeine exactly as prescribed, and do not exceed the recommended dose.
  • Avoid alcohol or sedative medications while taking codeine to prevent enhanced sedation or respiratory depression.
  • Drink plenty of water and consider dietary fibre or laxatives to prevent constipation.
  • Inform your doctor if pain persists or worsens, or if you experience severe side effects like breathing difficulties.
  • Store in a secure location to prevent misuse or accidental ingestion by others.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
Codeine PhosphateVarious Generic Options$10–20 (30 tablets, 30 mg)
Co-codamol (Codeine + Paracetamol)Various$15–25 (30 tablets, 30/500 mg)
Tylenol with CodeineMcNeil Consumer Healthcare$20–30 (30 tablets)

18. FAQs (15 Questions)

  1. What is codeine used for?
    Codeine is used to relieve mild to moderate pain, suppress dry coughs, and manage diarrhoea in certain cases.
  2. How does codeine work?
    It is metabolised into morphine, which binds to opioid receptors to reduce pain and suppress cough.
  3. Can codeine cause addiction?
    Yes, prolonged use can lead to dependence and withdrawal symptoms if stopped suddenly.
  4. What are the common side effects of codeine?
    Drowsiness, nausea, constipation, and dizziness.
  5. Can codeine be given to children?
    It is not recommended for children under 12 years and should be used cautiously in those aged 12–18.
  6. Can codeine be taken during pregnancy?
    It should be avoided unless necessary, as it may cause neonatal withdrawal or respiratory depression.
  7. Can codeine cause constipation?
    Yes, constipation is a common side effect. Drinking water and eating fibre may help.
  8. Can I drink alcohol while taking codeine?
    No, alcohol increases the risk of sedation and respiratory depression.
  9. What should I do if I miss a dose?
    Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double the dose.
  10. What happens if I overdose on codeine?
    Overdose can cause severe respiratory depression, confusion, and unconsciousness. Seek immediate medical attention.
  11. How long does it take for codeine to work?
    Pain relief typically starts within 30–60 minutes and lasts 4–6 hours.
  12. Can codeine be used for long-term pain?
    No, it is generally for short-term use due to the risk of dependence.
  13. Can codeine cause respiratory depression?
    Yes, especially at higher doses or in sensitive individuals like children or the elderly.
  14. Is codeine available over the counter?
    In many countries, low-dose codeine is available in combination with other drugs (e.g., paracetamol) over the counter, but regulations vary.
  15. How should codeine be stored?
    Store at room temperature, away from light and moisture, in a secure location to prevent misuse.