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Principles of Sports Medicine & Exercise Science

Codeine

by Jason J. Schwartz

Category: Addiction risk; Opioid

Also known as: Methylmorphine; Morphine methyl ester; 3-methylmorphine

Specialties and related fields: Oncology, orthopedics, pain management, pharmacology, sports medicine

Definition: a sleep-inducing and analgesic drug derived from morphine

KEY TERMS

analgesic: a drug that relieves pain

opiate: a substance derived from opium that relieves pain and induces sleep

opioid: compounds that resemble opium in their pain-relieving and sleep-inducing properties

HISTORY OF USE

Codeine was isolated from opium by French chemist Pierre-Jean Robiquet in 1832. It was used in the nineteenth century for pain relief and diabetes control. Near the end of the nineteenth century, codeine was used to replace morphine, another substance found in the opium poppy, because of the highly addictive properties of morphine. Codeine has effects similar to, albeit weaker than morphine, and was not thought to be addictive. Codeine was subsequently used in treatment for withdrawal from morphine.

A spoonful of promethazine/codeine syrup showing the characteristic purple color. “Purple drank” is a recreational drug created by combining prescription-grade cough syrup with a soft drink and hard candy. Effects include mild euphoric side effects and lethargy, drowsiness, and dissociative feelings. The first detailed report of codeine addiction is thought to be from 1905, and reports by others followed. In the 1930s, concern over the widespread misuse of codeine in Canada was noted. Codeine misuse in the United States was evaluated more fully in the 1960s, leading to the inclusion of codeine as a Schedule II controlled substance. Schedule II drugs have a high potential for misuse.

Subsequently, among substance misusers, prescription cough syrups containing codeine began to be mixed with soft drinks and candy (in a combination known as “lean syrup,” “sizzurp,” or “purple drank”). The combination remains a substance of concern.

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Photo via iStock/Hailshadow. [Used under license.]

EFFECTS AND POTENTIAL RISKS

Codeine primarily exerts its medicinal effects by being metabolized by liver enzymes to morphine, which binds to specific receptors in the central and peripheral nervous systems. Morphine effectively blocks the transmission of pain signals to the brain and inhibits the cough reflex. The metabolites also contribute to the usefulness of codeine in treating diarrhea by affecting, among other things, the contraction of gastrointestinal tract muscles.

Short-term use of codeine provides pain relief and euphoric effects. Some of the more common side effects of codeine ingestion include itching, constipation, dizziness, sedation, flushing, sweating, nausea, vomiting, and hives.

Long-term use of codeine can lead to tolerance, necessitating higher doses to achieve the same euphoric effect. Endorphin (natural painkiller) production may be slowed or stopped, causing increased sensitivity to pain if codeine is not used. More serious side effects include respiratory depression, central nervous system depression, seizures, and cardiac arrest.

Further Reading

1 

Benini, Franca, and Egidio Barbi. “Doing without Codeine: Why and What Are the Alternatives?” Italian Journal of Pediatrics, vol. 40, no. 1, 2014, doi:10.1186/1824-7288-40-16.

2 

Bhandari, Monika, et al. “Recent Updates on Codeine.” Pharmaceutical Methods, vol. 2, no. 1, 2011, pp. 3-8, doi:10.4103/2229-4708.81082.

3 

Carney, Tara, et al. “A Comparative Analysis of Pharmacists’ Perspectives on Codeine Use and Misuse—A Three Country Survey.” Substance Abuse Treatment, Prevention, and Policy, vol. 13, no. 1, 2018, doi:10.1186/s13011-018-0149-2.

4 

“Codeine.” MedlinePlus, 15 Mar. 2018, medlineplus.gov/druginfo/meds/a682065.html.

5 

Smith, Cooper. “Codeine: Drug Effects, Addiction, Abuse and Treatment-Rehab Spot.” RehabSpot, 9 July 2019, www.rehabspot.com/opioids/codeine/.

Citation Types

Type
Format
MLA 9th
Schwartz, Jason J. "Codeine." Principles of Sports Medicine & Exercise Science, edited by Michael A. Buratovich, Salem Press, 2022. Salem Online, online.salempress.com/articleDetails.do?articleName=POSpKin_0128.
APA 7th
Schwartz, J. J. (2022). Codeine. In M. A. Buratovich (Ed.), Principles of Sports Medicine & Exercise Science. Salem Press. online.salempress.com.
CMOS 17th
Schwartz, Jason J. "Codeine." Edited by Michael A. Buratovich. Principles of Sports Medicine & Exercise Science. Hackensack: Salem Press, 2022. Accessed September 16, 2025. online.salempress.com.