Acetaminophen and Codeine Phosphate

What it is used for

This medicine is used for the management of mild to moderate pain when an opioid is appropriate and alternative treatments are not enough or not tolerated.

How it is taken

Use the lowest effective dose for the shortest time needed. The usual adult dose depends on the tablet strength: for 15 mg codeine/300 mg acetaminophen, take 1 to 2 tablets every 4 hours as needed; for 30 mg codeine/300 mg acetaminophen, take 1 to 2 tablets every 4 hours; for 60 mg codeine/300 mg acetaminophen, take 1 tablet every 4 hours. Do not exceed 4000 mg of acetaminophen in 24 hours. Do not stop suddenly without talking to your doctor.

Warnings

• Risk of addiction, abuse, and misuse, which can lead to overdose and death.
• Life-threatening respiratory depression can occur even at recommended doses; risk is highest in the first 24-72 hours and after dose increases.
• Contraindicated in children under 12 years and for post-operative pain after tonsillectomy/adenoidectomy in children under 18.
• Ultra-rapid metabolizers of codeine (certain genetic types) can convert codeine to morphine too quickly, leading to fatal breathing problems.
• Neonatal opioid withdrawal syndrome can occur if used during pregnancy.
• Hepatotoxicity (liver damage) can occur with acetaminophen doses exceeding 4000 mg per day.
• Concomitant use with benzodiazepines or other CNS depressants increases risk of profound sedation, respiratory depression, coma, and death.
• Do not use with MAOIs or within 14 days of stopping them.
• May cause severe hypotension, adrenal insufficiency, serotonin syndrome, and seizures.
• Do not stop abruptly; taper dose to avoid withdrawal symptoms.

Common side effects

• Drowsiness
• Lightheadedness
• Dizziness
• Sedation
• Shortness of breath
• Nausea
• Vomiting
• Sweating
• Constipation

Interactions

This medicine can interact with many drugs, including anticoagulants (e.g., warfarin), CYP2D6 inhibitors (e.g., paroxetine, fluoxetine), CYP3A4 inhibitors (e.g., erythromycin, ketoconazole), CYP3A4 inducers (e.g., rifampin, carbamazepine), benzodiazepines, other CNS depressants (including alcohol), serotonergic drugs, MAOIs, mixed agonist/antagonist opioids, muscle relaxants, diuretics, and anticholinergic drugs. These interactions can increase risk of respiratory depression, sedation, serotonin syndrome, or reduce effectiveness.