How to Buy Codeine Online
- What codeine is and how it is classified
- How it works (prodrug mechanism, CYP2D6 metabolism)
- FDA-approved uses and controlled substance schedule
- Dosage forms, strengths, and typical dosing
- Common and serious side effects
- Drug interactions and contraindications
- Precautions, pediatric warnings, and when to contact a clinician
- Personalized medical advice or treatment recommendations
- Specific dosing for your individual condition
- Information about purchasing medications
- Alternatives to prescribed treatments (consult your provider)
Page Contents
What Is Codeine?
Codeine is a naturally occurring opioid alkaloid derived from the opium poppy (Papaver somniferum). It is one of the oldest and most widely used opioids in the world, with both analgesic (pain-relieving) and antitussive (cough-suppressing) properties.
Codeine is available in numerous formulations, including single-ingredient tablets and solutions, as well as combination products with acetaminophen (Tylenol with Codeine), aspirin (Empirin with Codeine), or in cough syrups. It is also a component of many prescription cough and cold preparations.
Codeine is typically designated as a Schedule V controlled substance, though higher-dose formulations or certain combinations may be classified as Schedule II or Schedule III.
How Codeine Works
Codeine itself has relatively weak opioid receptor binding activity. Its analgesic effect is largely dependent on its metabolic conversion to morphine by the liver enzyme CYP2D6. This makes codeine a prodrug — it is converted to its active form in the body.
This CYP2D6 metabolism is critical to understanding codeine's effects:
- Normal metabolizers: Convert approximately 10% of codeine to morphine, providing mild to moderate pain relief.
- Ultra-rapid metabolizers: Convert more codeine to morphine, increasing the risk of toxicity and respiratory depression.
- Poor metabolizers: Convert very little codeine to morphine, experiencing minimal pain relief.
The codeine that is not converted to morphine is metabolized to codeine-6-glucuronide, which also has some analgesic activity.
FDA Schedule & Classification
| Drug Name | Codeine (various brand names) |
|---|---|
| Drug Class | Opioid Analgesic / Antitussive |
| DEA Schedule | Schedule V (C-V) (may be Schedule II in higher doses or specific combinations) |
| Controlled Substance Act | Lowest schedule for opioids; limited preparations may be available OTC in some states |
| Prescription Required | Yes (some OTC formulations exist in certain jurisdictions) |
| FDA Approval | 1832 (historical use; modern formulations approved later) |
| Availability | Generic and brand-name (Tylenol with Codeine, Promethazine with Codeine) |
FDA-Approved Uses
Codeine is FDA-approved for:
- Mild to moderate pain: Dental pain, headache, post-surgical pain (when non-opioid analgesics are insufficient).
- Cough suppression (antitussive): Used in prescription cough medications to suppress cough reflex. The FDA has also restricted codeine-containing cough medications in children.
Codeine is considered one of the weakest opioid analgesics and is generally reserved for situations where non-opioid analgesics are insufficient but stronger opioids are not warranted.
Dosage Forms & Strengths
Immediate-Release Tablets
| Strength | Typical Dose (Adults) |
|---|---|
| 15 mg | 15-60 mg every 4-6 hours as needed |
| 30 mg | Individualized based on response |
| 60 mg | Individualized; higher doses may be Schedule II |
The typical adult dose for pain is 15-60 mg every 4 to 6 hours as needed. The maximum recommended daily dose is 360 mg for immediate-release formulations.
Combination Products
| Product | Codeine/Acetaminophen | Typical Starting Dose |
|---|---|---|
| Tylenol with Codeine #3 | 30 mg / 300 mg | 1-2 tablets every 4-6 hours |
| Tylenol with Codeine #4 | 60 mg / 300 mg | 1 tablet every 4-6 hours |
Cough Syrups
| Formulation | Codeine Content per 5 mL | Typical Dose (Adults) |
|---|---|---|
| Promethazine with Codeine | 10 mg | 5 mL every 4-6 hours |
| Guaifenesin with Codeine | 10 mg | 5-10 mL every 4-6 hours |
Elderly patients and those with hepatic impairment may require lower doses. Genetic testing for CYP2D6 status may be considered in some clinical scenarios.
Side Effects
Common Side Effects
- Constipation — the most common side effect
- Nausea and vomiting
- Drowsiness and sedation
- Dizziness
- Headache
- Dry mouth
- Itching (pruritus)
- Sweating
Serious Side Effects
Contact your healthcare provider or seek emergency medical attention if you experience:
- Respiratory depression — slow, shallow, or stopped breathing; can be life-threatening, especially in CYP2D6 ultra-rapid metabolizers
- Severe allergic reaction (anaphylaxis) — hives, difficulty breathing, swelling of face/throat
- Severe hypotension — dangerously low blood pressure
- Urinary retention — difficulty urinating
- Serotonin syndrome — rare with codeine alone, but possible when combined with serotonergic drugs
- Adrenal insufficiency — chronic use may suppress adrenal function
Drug Interactions
Codeine is metabolized primarily by CYP2D6 (to morphine) and CYP3A4 (to norcodeine). Drugs affecting these enzymes can significantly alter codeine's effect.
Major Interactions (Avoid or Use Extreme Caution)
- CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine, bupropion) — may reduce conversion to morphine, decreasing efficacy
- Benzodiazepines — concurrent use can cause profound sedation, respiratory depression, coma, and death
- Alcohol — significantly increases sedation and respiratory depression risk; never combine
- Other CNS depressants — muscle relaxants, sleep aids, antihistamines — additive sedation and respiratory depression
- MAO inhibitors — can cause serotonin syndrome or excitatory reactions; avoid concurrent use
Moderate Interactions (Monitor Closely)
- CYP3A4 inhibitors (ketoconazole, erythromycin) — may decrease codeine's conversion to inactive metabolites
- Tricyclic antidepressants — additive CNS depression
- Anticholinergic drugs — additive constipation and urinary retention
Dependence and Withdrawal
Codeine carries risk of physical and psychological dependence, though generally lower than stronger opioids. Withdrawal symptoms may include:
- Anxiety and restlessness
- Muscle aches
- Nausea and diarrhea
- Insomnia
- Goosebumps and sweating
Do not stop taking codeine abruptly after prolonged use. Tapering should occur under medical supervision.
Precautions & Warnings
- Pediatric contraindication: The FDA has contraindicated codeine use in children under 12 years of age due to risk of serious respiratory depression and death. It is also not recommended for children 12-18 who are obese or have conditions that could increase sensitivity.
- CYP2D6 ultra-rapid metabolizers: These individuals convert codeine to morphine much faster than normal, leading to dangerously high morphine levels. Genetic testing may be warranted.
- Respiratory depression: The most serious risk. Higher risk at higher doses, in elderly patients, and when combined with other CNS depressants.
- Pregnancy: Prolonged use during pregnancy may result in neonatal opioid withdrawal syndrome. Use only when clearly needed.
- Breastfeeding: Codeine is excreted in breast milk and is generally not recommended during breastfeeding, especially for CYP2D6 ultra-rapid metabolizers.
- Elderly patients: Increased sensitivity to opioids. Start at lower doses and titrate slowly.
- Liver disease: Codeine is metabolized by the liver. Patients with hepatic impairment require dose reduction.
- Gallbladder disease: Opioids can cause spasm of the sphincter of Oddi, worsening gallbladder pain.
- Driving and machinery: Codeine causes drowsiness and impairs coordination. Do not drive or operate heavy machinery until you know how this medication affects you.
When to Contact a Clinician
Reach out to your healthcare provider if you experience any of the following:
- Symptoms are not improving or are worsening after starting the medication
- You notice new or unexpected side effects
- You feel you need to take more medication to achieve the same effect (tolerance)
- You are having difficulty functioning at work or home due to sedation
- You are experiencing mood changes, depression, or thoughts of self-harm
- You are pregnant or planning to become pregnant
- You have questions about how long you should take this medication
- You want to stop the medication — never stop abruptly without medical guidance
Seek emergency care immediately if you experience seizures, difficulty breathing, severe allergic reaction, or loss of consciousness.
Further Reading
- FDA — Codeine Prescribing Information (AccessData, FDA)
- MedlinePlus — Codeine (National Library of Medicine)
- DailyMed — Codeine Labels (National Library of Medicine)
- PubChem — Codeine (National Institutes of Health)
- FDA — Codeine Safety Communication