Codeine is an opioid medication used to relieve pain and, in certain prescription formulations, to suppress cough. It may be available alone or combined with other medicines such as acetaminophen, aspirin, or other cough-and-cold ingredients. Because codeine can cause respiratory depression, misuse, addiction, overdose, and physical dependence, it requires careful prescribing and use.
A particularly important safety issue is that people metabolize codeine differently. The body converts some codeine into morphine, and individuals who convert it to morphine unusually quickly can experience unexpectedly high morphine exposure and potentially life-threatening respiratory depression.
In the United States, the FDA has also placed important restrictions on prescription opioid cough and cold medicines containing codeine, limiting these products to adults 18 and older because the risks outweigh the benefits in younger patients.
What Is Codeine?
Codeine is an opioid medication with two principal therapeutic roles: pain relief and cough suppression in certain formulations. The FDA describes codeine as an opioid pain reliever used for mild to moderately severe pain and notes that it is also used, generally in combination with other medications, to reduce coughing.
Codeine products can contain codeine as the only active ingredient or combine it with another medication.
Examples include combinations with:
- Acetaminophen
- Aspirin
- Certain cough-and-cold ingredients
The specific indication, age restrictions, warnings, and dosing depend on the particular product. Therefore, “codeine” is not one single medication formulation with identical instructions for every patient.
How Does Codeine Work?
Codeine acts primarily through the central nervous system.
For pain, it changes how the brain and nervous system perceive and respond to painful signals. For cough, codeine decreases activity in areas of the brain involved in the cough reflex.
An important characteristic of codeine is that some of it is metabolized into morphine.
The amount of morphine produced varies between people because of differences in metabolism, particularly involving the CYP2D6 enzyme pathway.
This variability helps explain why codeine can produce substantially different effects from one person to another.
Codeine Uses
1. Codeine for Pain Relief
Codeine can be used as an opioid analgesic to treat certain types of pain.
FDA information describes codeine as a pain reliever for mild to moderately severe pain.
Depending on the formulation, codeine may be prescribed alone or combined with another analgesic.
For example, combination products may contain codeine and acetaminophen. In these products, the therapeutic effects and safety considerations come from both ingredients, not codeine alone.
Codeine is not appropriate for every type of pain
Modern pain management emphasizes matching treatment to the cause and severity of pain.
For many common types of acute pain, nonopioid therapies can provide comparable or better pain relief with fewer opioid-related risks. The CDC recommends considering nonpharmacologic and nonopioid therapies and using opioids for acute pain when anticipated benefits outweigh risks.
When an opioid is appropriate, treatment should be individualized according to the patient’s condition, risks, expected duration of severe pain, and response to treatment.
Codeine for Cough
Codeine has also been used as an antitussive, meaning a medicine that suppresses coughing.
However, this use requires particularly careful consideration.
The FDA states that codeine may be used to reduce coughing, generally in combination with other medicines.
In the United States, prescription opioid cough-and-cold medicines containing codeine or hydrocodone are not indicated for people younger than 18 years. The FDA made this change because the risks—including slowed or difficult breathing, misuse, addiction, overdose, and death—outweigh the benefits in children and adolescents.
A cough associated with an uncomplicated cold or upper respiratory infection often resolves on its own, and opioid cough medicines should not automatically be considered necessary.
Codeine and Children: Important FDA Restrictions
Codeine requires particular caution in children and adolescents.
The FDA has issued multiple safety warnings concerning codeine because some children can metabolize codeine into morphine unusually rapidly, potentially resulting in dangerously high morphine concentrations.
The FDA has:
- Restricted certain codeine pain and cough medicines in children.
- Added strong warnings regarding respiratory depression.
- Contraindicated codeine for certain pediatric postoperative situations.
- Restricted prescription opioid cough-and-cold medicines containing codeine to adults 18 and older.
Codeine after tonsil or adenoid surgery
Codeine should not be used for pain in children younger than 18 following tonsillectomy and/or adenoidectomy because of the risk of potentially fatal respiratory depression associated with variable metabolism.
Parents and caregivers should always verify whether a medicine contains codeine before giving prescription or combination cough, cold, or pain products to a child.
Codeine and Breastfeeding
Codeine also presents an important concern during breastfeeding.
The FDA recommends against breastfeeding during treatment with codeine because codeine and its metabolites can pass into breast milk and potentially cause serious harm to a nursing infant.
Reported infant effects can include:
- Excessive sleepiness
- Difficulty breastfeeding
- Breathing problems
- Potentially fatal respiratory depression
People who are pregnant, planning pregnancy, or breastfeeding should discuss opioid treatment with a healthcare professional before using codeine.
Common Codeine Side Effects
Like other opioids, codeine can cause several predictable adverse effects.
Common effects may include:
- Drowsiness
- Dizziness
- Nausea
- Vomiting
- Constipation
- Lightheadedness
- Headache
- Shortness of breath
The FDA identifies drowsiness, dizziness, nausea, vomiting, constipation, shortness of breath, and headache among common opioid adverse effects.
Not everyone experiences these effects, and severity can vary according to dose, duration of treatment, individual sensitivity, other medications, and metabolic differences.
Codeine and Respiratory Depression
One of the most serious risks associated with codeine is respiratory depression.
Respiratory depression means breathing becomes abnormally slow, shallow, or inadequate.
According to MedlinePlus, codeine can cause serious or life-threatening breathing problems, particularly during the first 24 to 72 hours of treatment or after a dose is increased.
Warning signs can include:
- Slow breathing
- Long pauses between breaths
- Shortness of breath
- Extreme sleepiness
- Difficulty waking
- Unresponsiveness
- Bluish or grayish skin, lips, or fingertips
Severe respiratory depression is a medical emergency.
Codeine and CYP2D6: Why People Respond Differently
One of the most distinctive safety considerations with codeine is its metabolism.
The body converts codeine into morphine through the CYP2D6 metabolic pathway.
People with different CYP2D6 activity can therefore experience different levels of morphine exposure.
Ultra-rapid metabolizers
People who are ultra-rapid CYP2D6 metabolizers can convert codeine into morphine more rapidly than expected.
This can result in unusually high morphine concentrations and potentially life-threatening respiratory depression.
This variability is one reason the FDA has placed particularly strong restrictions on codeine use in children and breastfeeding women.
This also demonstrates why simply assuming that a standard codeine dose will have the same effect on everyone can be unsafe.
Codeine Dependence, Misuse and Addiction
Codeine is an opioid and therefore has potential for:
- Misuse
- Abuse
- Addiction
- Physical dependence
- Overdose
MedlinePlus warns that codeine can be habit-forming and should be taken exactly as prescribed.
Physical dependence vs. addiction
These terms should not be confused.
Physical dependence means the body has adapted to regular opioid exposure. Stopping suddenly can cause withdrawal symptoms.
Addiction is a chronic disorder involving problematic, compulsive substance use despite harmful consequences and impaired control.
A patient can become physically dependent on an opioid even when taking it as prescribed.
Codeine Withdrawal
Regular opioid use can lead to physical dependence.
If codeine has been used regularly, abruptly stopping it can cause withdrawal symptoms.
Possible symptoms include:
- Anxiety
- Restlessness
- Sweating
- Runny nose
- Muscle aches
- Abdominal cramping
- Diarrhea
- Nausea
- Insomnia
- Increased heart rate
The appropriate approach to discontinuing long-term opioid treatment depends on the patient’s circumstances. The CDC emphasizes individualized decisions regarding continuation and tapering rather than abrupt or inflexible discontinuation.
Patients taking codeine regularly should therefore discuss discontinuation with their healthcare professional rather than stopping suddenly on their own.
Codeine and Opioid Overdose
An opioid overdose can occur when opioid effects become strong enough to suppress breathing.
The risk can increase with:
- Excessive doses
- Taking codeine more frequently than prescribed
- Combining codeine with other opioids
- Combining opioids with alcohol
- Combining opioids with sedatives
- Accidental ingestion
- Individual differences in metabolism
MedlinePlus recommends discussing access to an opioid overdose rescue medication such as naloxone or nalmefene with a healthcare professional or pharmacist. These medications can reverse life-threatening opioid effects during an overdose.
Codeine and Alcohol
Alcohol can increase the sedating and respiratory-depressant effects of opioids.
Combining codeine with alcohol may increase the risk of:
- Extreme sedation
- Dizziness
- Loss of coordination
- Respiratory depression
- Unconsciousness
- Overdose
- Death
The FDA specifically warns that alcohol can increase the serious and potentially life-threatening effects of opioid medicines.
People taking codeine should discuss alcohol use with their healthcare professional rather than assuming that combining the two is safe.
Codeine With Benzodiazepines and Other CNS Depressants
Combining codeine with other medications that slow the central nervous system can increase the risk of respiratory depression.
Examples include:
- Benzodiazepines
- Certain sleep medicines
- Other opioids
- Some sedating antihistamines
- Alcohol
- Other CNS depressants
This is particularly important because medicines such as clonazepam, alprazolam, lorazepam, and diazepam are also capable of causing significant central nervous system depression.
Patients should provide a complete medication list before starting codeine.
Codeine Combination Products: Read the Entire Label
Codeine is frequently combined with other active ingredients.
This creates an important safety issue: a person may be exposed to risks from more than one medication at the same time.
For example, codeine-acetaminophen products contain both an opioid and acetaminophen.
Taking additional acetaminophen-containing products without realizing that acetaminophen is already present can result in excessive total acetaminophen exposure and potentially serious liver injury.
The same principle applies to cough-and-cold products containing multiple active ingredients.
Practical safety rule
Before taking another pain, cold, cough, or sleep medicine, check the active ingredients and ask a pharmacist if you’re unsure whether ingredients overlap.
Codeine and Constipation
Constipation is a common opioid effect.
Opioids can slow gastrointestinal movement, resulting in:
- Fewer bowel movements
- Hard stools
- Abdominal discomfort
- Straining
- Bloating
People taking codeine for more than a short period should discuss constipation prevention and treatment with their healthcare professional.
Severe abdominal pain, persistent vomiting, or an inability to pass stool or gas requires medical evaluation.
Codeine and Driving
Codeine may cause drowsiness, dizziness, impaired coordination, or reduced alertness.
These effects can make driving or operating machinery dangerous, particularly when treatment is first started or the dose is changed.
Alcohol and other sedating medicines can further increase impairment.
Patients should understand how codeine affects them before performing activities that require full alertness.
Codeine for Acute Pain: Where Does It Fit?
Modern pain treatment emphasizes multimodal pain management, meaning that different approaches may be combined to achieve adequate pain control while minimizing opioid exposure.
The CDC states that nonopioid therapies are at least as effective as opioids for many common types of acute pain and recommends considering nonopioid and nonpharmacologic therapies before initiating opioid treatment when appropriate.
When opioids are appropriate for acute pain, the CDC recommends immediate-release opioids rather than extended-release or long-acting opioids when initiating opioid therapy. It also recommends using the lowest effective dosage and limiting treatment to the expected duration of pain severe enough to require opioids.
These recommendations are intended as clinical guidance, not rigid rules for every patient.
Who May Need Extra Caution With Codeine?
A healthcare professional should carefully evaluate codeine use in people with certain medical conditions or risk factors, including:
- Breathing disorders
- Sleep-related breathing problems
- Older age or frailty
- Liver or kidney problems
- History of substance-use disorder
- Previous opioid overdose
- Use of benzodiazepines or other sedatives
- Use of other opioids
- Pregnancy or breastfeeding
- Recent surgery involving tonsils or adenoids in children
- Medications that affect opioid metabolism
The FDA and MedlinePlus emphasize individualized risk assessment because codeine’s effects can vary considerably between people.
Codeine Storage and Safe Handling
Because codeine is an opioid with misuse potential, safe storage is important.
Patients should:
- Keep codeine in a secure location.
- Never share it with another person.
- Keep it away from children and teenagers.
- Follow medication-storage instructions.
- Dispose of unused medication according to appropriate disposal guidance.
Sharing prescription opioids can expose another person to serious harm even if the medication was originally prescribed appropriately for the patient.
Codeine vs. Other Opioids
Codeine belongs to the opioid class along with medicines such as:
- Morphine
- Oxycodone
- Hydrocodone
- Hydromorphone
- Fentanyl
- Tramadol
These medications differ in potency, metabolism, approved indications, formulations, and safety profiles.
Codeine is unusual because its analgesic activity depends partly on conversion to morphine, making individual metabolic differences particularly relevant.
A medication that works well for one patient may not be appropriate for another.
When Is Codeine an Emergency?
Seek emergency medical care if someone taking codeine develops:
- Very slow or difficult breathing
- Long pauses between breaths
- Extreme sleepiness
- Inability to wake
- Loss of consciousness
- Blue, gray, or pale lips or skin
- Suspected opioid overdose
- Severe allergic reaction
If an opioid overdose is suspected, naloxone or nalmefene, when available and appropriate, can reverse opioid effects while emergency medical help is obtained. MedlinePlus recommends discussing access to these rescue medicines with a healthcare professional or pharmacist.
Frequently Asked Questions About Codeine
What is codeine used for?
Codeine is an opioid used for pain relief and, in certain formulations, to suppress cough. The specific indication depends on the product.
Is codeine an opioid?
Yes. Codeine is an opioid medication with analgesic and antitussive uses.
Is codeine used for cough?
Yes, codeine is used in certain prescription cough formulations. However, the FDA restricts prescription opioid cough-and-cold medicines containing codeine to adults 18 and older in the United States.
Can children take codeine?
Codeine has important pediatric restrictions. Prescription opioid cough-and-cold products containing codeine are not indicated for people younger than 18, and codeine is contraindicated in certain pediatric situations because of the risk of life-threatening respiratory depression.
Why is codeine dangerous for some people?
People metabolize codeine differently. Some individuals convert codeine to morphine unusually rapidly, potentially producing dangerously high morphine exposure and respiratory depression.
Can codeine cause addiction?
Yes. Codeine can be misused and can cause addiction and physical dependence. It should be taken only as directed.
Can codeine cause breathing problems?
Yes. Respiratory depression is one of the most serious risks of codeine. The risk can be increased by higher doses, dose increases, individual metabolic differences, alcohol, opioids, and other CNS depressants.
Can codeine be taken with alcohol?
Combining codeine with alcohol can increase central nervous system depression and potentially life-threatening breathing problems. Patients should avoid this combination unless specifically advised otherwise by a healthcare professional.
Is codeine safe during breastfeeding?
The FDA recommends against breastfeeding during treatment with codeine because exposure through breast milk can cause serious or potentially fatal effects in infants.
Does codeine cause constipation?
Yes. Constipation is a common effect of opioid medicines, including codeine. Persistent or severe gastrointestinal symptoms should be discussed with a healthcare professional.
Can I stop codeine suddenly?
If codeine has been used regularly, stopping suddenly can cause opioid withdrawal. The appropriate discontinuation strategy depends on the individual’s treatment and should be discussed with a healthcare professional.
Key Takeaways
Codeine is an opioid used for pain relief and in certain prescription cough formulations.
The most important points are:
- Codeine can relieve certain types of pain.
- It can suppress cough in some prescription formulations.
- The body converts some codeine into morphine.
- Individual differences in metabolism can produce substantially different effects.
- Respiratory depression is one of the most serious risks.
- Codeine can cause misuse, addiction, physical dependence, and withdrawal.
- Alcohol, benzodiazepines, and other CNS depressants can increase dangerous sedation and respiratory depression.
- Children and adolescents have important FDA restrictions concerning codeine.
- Prescription opioid cough-and-cold medicines containing codeine are limited to adults 18 and older in the United States.
- Codeine is not recommended during breastfeeding because of potential serious harm to infants.
- Combination products require careful attention to all active ingredients.
- Naloxone or nalmefene may be used to reverse life-threatening opioid overdose effects.
- For many common acute pain conditions, nonopioid therapies may be preferred, with opioid treatment considered when expected benefits outweigh risks.
Medical Disclaimer
This article is intended for educational and informational purposes only and does not replace professional medical advice, diagnosis, or treatment. Codeine is a prescription opioid with potentially serious risks, including respiratory depression, misuse, addiction, dependence, and overdose. Do not change the dose, combine codeine with alcohol or other sedating medicines, or discontinue regular opioid treatment without appropriate medical guidance.
If someone taking codeine develops severe breathing difficulty, cannot be awakened, loses consciousness, or is suspected of having an opioid overdose, seek emergency medical assistance immediately.
