Gamma Butyrolactone (gbl) - Codeine Phosphate Interaction
Herbal: Gamma Butyrolactone (gbl)
Also Known As: 2-3 dihydro furanone
Drug: Codeine Phosphate
Brand names:
Codeine

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 04, 2025
Interaction Details
Codeine Phosphate is classified as belonging to the following category: Cns Depressants
Theoretically, concomitant use of GBL with CNS depressants may potentiate respiratory and CNS depression.
GBL is metabolized to gamma-hydroxybutyrate (GHB). Concomitant use of CNS depressants with GHB may cause serious CNS and respiratory depression.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Anon. Important message for health professionals: Report serious adverse events associated with dietary supplements containing GBL, GHB or BD. Food and Drug Administration, Rockville, MD. August 25, 1999. Available at: http://vm.cfsan.fda.gov/~dms/mwg
- Anon. Multistate outbreak of poisonings associated with illicit use of gamma hydroxy butyrate. JAMA 1991;265:447-8.
- Product information for Xyrem. Jazz Pharmaceuticals, Inc. Palo Alto, CA. March 2022.
Interaction Details
Codeine Phosphate is classified as belonging to the following category: Narcotic Drugs
Theoretically, concomitant use of GBL with narcotic drugs may potentiate respiratory and central nervous system (CNS) depression.
GBL is metabolized to gamma-hydroxybutyrate (GHB). Concomitant use of narcotic drugs with GHB may cause serious CNS and respiratory depression. In one case report, concurrent use of GHB and heroin was fatal.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Anon. Important message for health professionals: Report serious adverse events associated with dietary supplements containing GBL, GHB or BD. Food and Drug Administration, Rockville, MD. August 25, 1999. Available at: http://vm.cfsan.fda.gov/~dms/mwg
- Anon. Multistate outbreak of poisonings associated with illicit use of gamma hydroxy butyrate. JAMA 1991;265:447-8.
- Ferrara SD, Tedeschi L, Frison G, Rossi A. Fatality due to gamma-hydroxybutyric acid (GHB) and heroin intoxication. J Forensic Sci 1995;40:501-4.
- Product information for Xyrem. Jazz Pharmaceuticals, Inc. Palo Alto, CA. March 2022.
Gamma Butyrolactone (gbl) Overview

Codeine Phosphate Overview
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Codeine is used to relieve mild to moderate pain. It is also used, usually in combination with other medications, to reduce coughing. Codeine will help relieve symptoms but will not treat the cause of symptoms or speed recovery. Codeine belongs to a class of medications called opiate (narcotic) analgesics and to a class of medications called antitussives. When codeine is used to treat pain, it works by changing the way the brain and nervous system respond to pain. When codeine is used to reduce coughing, it works by decreasing the activity in the part of the brain that causes coughing.
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Codeine is also available in combination with acetaminophen (Capital and Codeine, Tylenol with Codeine), aspirin, carisoprodol, and promethazine and as an ingredient in many cough and cold medications. This monograph only includes information about the use of codeine. If you are taking a codeine combination product, be sure to read information about all the ingredients in the product you are taking and ask your doctor or pharmacist for more information.
Gamma Butyrolactone (gbl) - More Interactions
Gamma Butyrolactone (gbl) interacts with 268 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
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Drug descriptions are provided by MedlinePlus.