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Codeine Side Effects

Medically reviewed by Last updated on Apr 19, 2023.

Applies to codeine: oral tablet.


Oral route (Tablet)

Addiction, Abuse, and Misuse

Codeine sulfate exposes users to risks of addiction, abuse, and misuse, which can lead to overdose and death. Assess patient’s risk before prescribing and monitor regularly for these behaviors and conditions.Risk Evaluation and Mitigation Strategy (REMS)To ensure that the benefits of opioid analgesics outweigh the risks of addiction, abuse, and misuse, the Food and Drug Administration (FDA) has required a Risk Evaluation and Mitigation Strategy (REMS) for these products.

Life-Threatening Respiratory Depression

Serious, life-threatening, or fatal respiratory depression may occur. Monitor closely, especially upon initiation or following a dose increase.

Accidental Ingestion

Accidental ingestion of codeine sulfate, especially by children, can result in a fatal overdose of codeine.

Ultra-Rapid Metabolism of Codeine and Other Risk Factors for Life-Threatening Respiratory Depression in Children

Life-threatening respiratory depression and death have occurred in children who received codeine; most cases followed tonsillectomy and/or adenoidectomy and many of the children had evidence of being an ultra-rapid metabolizer of codeine due to a CYP2D6 polymorphism. Codeine sulfate is contraindicated in children younger than 12 years of age and in children younger than 18 years of age following tonsillectomy and/or adenoidectomy. Avoid the use of codeine sulfate in adolescents 12 to 18 years of age who have other risk factors that may increase their sensitivity to the respiratory depressant effects of codeine.

Neonatal Opioid Withdrawal Syndrome

Prolonged use of codeine sulfate during pregnancy can result in neonatal opioid withdrawal syndrome which may be life-threatening if not recognized and treated. If prolonged opioid use is required in a pregnant woman, advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available.

Interactions with Drug Affecting Cytochrome P450 Isoenzymes

The effects of concomitant use or discontinuation of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine are complex. Use of cytochrome P450 3A4 inducers, 3A4 inhibitors, or 2D6 inhibitors with codeine sulfate requires careful consideration of the effects on the parent drug, codeine, and the active metabolite, morphine.

Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants

Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate; limit dosages and durations to the minimum required; and follow patients for signs and symptoms of respiratory depression and sedation.

Serious side effects of Codeine

Along with its needed effects, codeine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking codeine:

Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur while taking codeine:

Symptoms of overdose

Other side effects of Codeine

Some side effects of codeine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Incidence not known

For Healthcare Professionals

Applies to codeine: compounding powder, injectable solution, oral solution, oral tablet.


The most frequently observed adverse reactions include drowsiness lightheadedness, dizziness, sedation, shortness of breath, nausea, vomiting, sweating, and constipation.[Ref]


Respiratory depression resulting in death has been reported in children who received codeine postoperatively following tonsillectomy and/or adenoidectomy. These children had evidence of being ultra-rapid metabolizers of codeine. Death has also been reported in nursing infants exposed to high levels of morphine in breast milk due to their breastfeeding mother being an ultra-rapid metabolizer of codeine.[Ref]

Uncommon (0.1% to 1%): Bronchospasm, laryngospasm, respiratory depression

Frequency not reported: Respiratory arrest, dyspnea

Postmarketing reports: Deaths due to respiratory depression[Ref]


Uncommon (0.1% to 1%): Heartbeat irregularities, blood pressure changes, syncope

Frequency not reported: Flushing, hypotension, palpitations, circulatory depression, shock, cardiac arrest, circulatory depression, bradycardia, tachycardia, edema[Ref]

Nervous system

Common (1% to 10%): Drowsiness, dizziness

Uncommon (0.1% to 1%): Headache, lightheadedness, feeling faint, paradoxical CNS stimulation (especially in children), disorientation, restlessness, shakiness, somnolence, weakness

Frequency not reported: Seizures[Ref]


Frequency not reported: Fatigue, vertigo, malaise, hypothermia, fever, addiction, tolerance, dependence, withdrawal reactions upon discontinuation of chronically administered drug included diarrhea, sweating, vomiting, insomnia, agitation, tremor, body aches, gooseflesh, loss of appetite, nervousness or restlessness, runny nose, sneezing, shivering, stomach cramps, nausea, sleep disturbances, yawning, weakness, tachycardia, fever, irritability, mydriasis[Ref]


Uncommon (0.1% to 1%): Itching, facial swelling, pruritus, urticaria, histamine release (hypotension, sweating, flushing of the face, tachycardia, breathlessness)

Frequency not reported: Allergic reactions including maculopapular rash[Ref]


Common (1% to 10%): Constipation

Uncommon (0.1% to 1%): Dry mouth, loss of appetite, nausea, vomiting, paralytic ileus, toxic megacolon, anorexia, stomach cramps

Frequency not reported: Gastrointestinal distress, anorexia, diarrhea, pancreatitis[Ref]


Frequency not reported: Biliary spasm[Ref]


Uncommon (0.1% to 1%): Urinary retention or hesitance, ureteric spasm, reduced libido and/or potency[Ref]


Uncommon (0.1% to 1%): Rash

Frequency not reported: Sweating, urticaria, pruritus[Ref]


Uncommon (0.1% to 1%): Miosis, blurred or double vision

Frequency not reported: Visual disturbances[Ref]


Uncommon (0.1% to 1%): Antidiuretic effect

Frequency not reported: Decreased libido or potency, erectile dysfunction, sexual dysfunction[Ref]


Uncommon (0.1% to 1%): Euphoria, dysphoria, unusual dreams, hallucinations, insomnia, anxiety

Frequency not reported: Mood changes, restlessness, confusion, mental depression[Ref]


Frequency not reported: Hyperglycemia, anorexia[Ref]

Frequently asked questions


1. Multum Information Services, Inc. Expert Review Panel

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Cerner Multum, Inc. Australian Product Information.

4. Product Information. Codeine Sulfate (codeine). Lannett Company Inc. 2015.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.