Codeine effects and side effects

Dear Alice,

What do codeine pills do to you? What are the side effects and whatever else you would add in for me?

— ty

Dear ty,

Curiosity about codeine can lead to copious information, so first it’s good to focus on the basics. Codeine is a prescription opioid/narcotic analgesic that’s typically used to reduce coughing or to relieve mild to moderate pain by acting on the central nervous system (CNS, more on this later). That said, it’s good to be aware of potential risks associated with taking this medication. Codeine has a number of potential side effects and can have harmful interactions with a number of substances (some medications, herbal supplements, alcohol, and narcotics). Depending upon the reason for the prescription, codeine may also be prescribed in combination with other medications, such as acetaminophen, which also carry risks for interactions and side effects. What’s more, codeine may also be habit-forming and is currently a Schedule II controlled substance by the United States government. This means that it has a medical use, but also has a “high potential for abuse.”  Because of these concerns and because this medication may not be appropriate for everyone, it's critical to only take codeine under the supervision of a medical professional. Ready for more information on this drug? Then keep reading!

Opioids like codeine attach to specific opioid receptors (found in the brain, spinal cord, and gastrointestinal tract), and when this happens, it effectively change the way a person experiences pain. Codeine can also affect regions of the brain that influence how a user perceives pleasure, which may result in an initial feeling of euphoria after taking the medication. Other possible side-effects include:

  • Drowsiness
  • Constipation
  • Depressed breathing
  • Dizziness
  • Light-headedness/feeling faint
  • Nausea or vomiting

If anyone taking codeine experiences seizures, convulsions, severe dizziness or drowsiness, low blood pressure, slow heartbeat, weakness, difficulty breathing, or extreme mood changes, it's considered an emergency and seeking immediate medical attention is recommended. What’s more, taking a large single dose of codeine could also cause severe respiratory depression and even death, so it’s critical that codeine be taken as prescribed.

Though it can be useful and effective medication, codeine isn't recommended for everyone. This includes folks who've had surgery on their tonsils or adenoids and those who are pregnant or breast feeding. Those taking certain medications (such as other CNS depressants) may also need to steer clear of codeine due to the risk of interactions that may increase the risk of breathing problems or other serious, life-threatening conditions such as sedation or coma. Along those lines, because the use of alcohol and illicit drugs can exacerbate the effects of codeine, avoiding them is advised while taking any medication containing codeine.

Lastly, it’s key to mention that codeine can be habit-forming. What does this mean? The body could become physically dependent to codeine, so a person might experience withdrawal symptoms after they stop using. It’s also possible that a user could develop tolerance, meaning a higher dose of codeine is needed to get the same effect as when they first started taking the medication. People also can become addicted to codeine and experience a compulsive (often uncontrollable) need to use in spite of negative consequences. To avoid dependence and addiction, it’s recommended that anyone using codeine avoid taking it in large doses or for longer than their health care provider has prescribed.

Though it’s good to heed these words of caution, codeine may be very effective in bringing relief to those in pain when used properly. Hope this helps quash your quandary about codeine, but if you’re still curious, MedlinePlus from the U.S. National Library of Medicine has even more information.

Last updated May 05, 2017
Originally published Aug 15, 2008