What are Common Codeine Side Effects?

Codeine is a less potent opioid drug, but it can still cause severe side effects, physical dependence, and addiction to develop.

Codeine is a prescription opioid medication used to treat pain and cough. Codeine is a commonly prescribed drug, but it still creates a variety of risks and side effects. As part of the opioid drug class, it’s also a contributor to the nationwide opioid epidemic.

Codeine is less potent than other opioids, such as hydrocodone and morphine. Although codeine also has a lower potential for abuse and addiction, these risks still exist when using the drug.

How Does Codeine Work?

When someone takes codeine, a portion of the drug converts to morphine when it reaches their brain. It then binds to opioid receptors found throughout the central nervous system and creates certain effects in the brain. Higher doses can create a flood of feel-good brain neurotransmitters, which is why some people feel high when using codeine and other opioids.

These effects also change how a person feels sensations of pain. Opioids like codeine increase pain tolerance, so a person feels less pain when using them. Opioids also slow the activity of the central nervous system when they bind to opioid receptors.

Codeine is often combined with acetaminophen to provide extra pain relief and reduce the amount of codeine needed. It can also be prescribed as a cough suppressant.

Codeine Side Effects and Health Risks

Codeine is a controlled substance in the U.S., meaning it can only be taken with a doctor’s prescription. Using codeine in ways other than prescribed is illegal.

Because codeine is one of the less potent opioids, people can tend to get lulled into a false sense of comfort about its use. However, codeine still carries a number of risks and related side effects.

Common Codeine Side Effects

Some of the common side effects of codeine can include:

• Slow heart rate
• Fainting
• Abnormal dreams
• Nausea and vomiting
• Constipation
• Drowsiness
• Fatigue

It is normal to experience some of these side effects, even when taking codeine as prescribed.

Severe Codeine Side Effects

Less common but severe side effects of codeine include:

• Shallow breathing
• Low blood pressure
• Extreme drowsiness
• Seizures
• Urination problems
• Confusion
• Agitation
• Hallucinations
• Death

Over time, codeine use can also cause addiction and dependence to develop. All opioids, including codeine, have a high risk for abuse and addiction. This is because codeine and other opioids can cause people to feel high, which triggers a cycle of rewarded behavior that leads to drug addiction.

Physical dependence occurs when someone’s brain and body become used to the presence of drugs like codeine. If the person suddenly stops taking the drug, they will experience withdrawal symptoms as their body adjusts to its absence. Dependence can occur even when someone takes opioids exactly as prescribed. As a result, physicians will often advise patients to follow a taper schedule when stopping the medication.

When codeine is combined with other drugs, such as acetaminophen, additional side effects are possible. Acetaminophen can cause liver damage and acute liver failure if taken in large amounts.

Codeine should never be combined with alcohol because it can cause further respiratory depression, which can lead to a fatal overdose. Additionally, mixing a codeine-acetaminophen combination with alcohol can increase the risk of liver problems.

If codeine is taken with sedatives like Xanax, it can cause confusion and additional sedative effects. These effects can be dangerous or deadly. You should always let your physician know about any other substances you use before taking codeine.

Is Codeine Bad For You?

If you use it exactly as directed by your doctor, codeine is considered safe but not entirely risk-free. If you abuse it, however, codeine can lead to health problems. For example:

• You can overdose on codeine due to extreme respiratory depression.
• You can develop dependence and addiction.
• You can experience severe side effects, such as seizures.

Before taking codeine, the best thing to do is make sure you have a complete conversation with your physician about possible side effects. Your doctor can discuss codeine with you and determine whether it’ll be a safe medication for you to use.

Editor – Jonathan Strum

Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more

Medically Reviewed By – Dr. Conor Sheehy, PharmD, BCPS, CACP

Dr. Sheehy completed his BS in Molecular Biology at the University of Idaho and went on to complete his Doctor of Pharmacy (PharmD) at the University of Washington in Seattle. Read more