Drug & supplement interaction

Gamma Butyrolactone (gbl) + Oxymorphone

Oxymorphone brand names: Numorphan, Opana, Opana ER, Opana Injection.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Oxymorphone falls into 2 drug categories that Gamma Butyrolactone (gbl) can interact with; the most serious is rated moderate. Theoretically, concomitant use of GBL with CNS depressants may potentiate respiratory and CNS depression.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Gamma Butyrolactone (gbl) and Oxymorphone

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Gamma Butyrolactone (gbl) interacts with whole categories of medication. Oxymorphone falls into 2 of those categories, so it can interact with Gamma Butyrolactone (gbl) in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CNS DEPRESSANTS

1 of 2

Why this applies to Oxymorphone

Oxymorphone falls under CNS DEPRESSANTS — the group Gamma Butyrolactone (gbl) interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Let me be very direct here. GBL is not a supplement, it is a toxic solvent your body turns into GHB, a powerful sedative. Pairing it with oxymorphone (Opana), a strong opioid painkiller, is a genuinely dangerous combination. Both of these slow your brain and breathing, and stacking two sedatives can multiply that effect.

What worries me most is breathing. Oxymorphone already causes deep drowsiness, slowed breathing, and can knock you unconscious. Adding GHB on top can push that into life-threatening respiratory depression, coma, or death. The formal evidence here is anecdotal, but the risk is real and predictable. Please do not use GBL. If you are struggling with sleep, pain, or substance use, talk with your doctor or pharmacist right away.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. Anon. Multistate outbreak of poisonings associated with illicit use of gamma hydroxy butyrate. JAMA 1991;265:447-8. DOI
  3. Product information for Xyrem. Jazz Pharmaceuticals, Inc. Palo Alto, CA. March 2022.
Moderate

NARCOTIC DRUGS

2 of 2

Oxymorphone also falls under 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.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

First things first: GBL isn't a supplement at all. It's a toxic solvent that your body rapidly turns into GHB, a heavy-duty sedative that's illegal to sell for human use. Please don't take it. If you're struggling with sleep, anxiety, or substance use, let's talk through safer options together.

Here's the danger when it's mixed with Oxymorphone (Opana): both are powerful brain and breathing depressants, and stacking them piles on that effect. Oxymorphone already slows your breathing, deepens drowsiness, and can drop your blood pressure. Add GHB on top and you risk dangerously slow or stopped breathing, deep sedation, and coma. The evidence here is anecdotal, but a real fatal case has been reported with this kind of combo. Never combine these. Please reach out to your pharmacist or doctor for help.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. Anon. Multistate outbreak of poisonings associated with illicit use of gamma hydroxy butyrate. JAMA 1991;265:447-8. DOI
  3. 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. DOI
  4. Product information for Xyrem. Jazz Pharmaceuticals, Inc. Palo Alto, CA. March 2022.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Gamma Butyrolactone (gbl) Also Interacts With Other Medications

Gamma Butyrolactone (gbl) has 270 moderate known drug interactions in our database — the Oxymorphone one above is among them. If you take anything else, check it against the full list below.

Moderate 270 No known interaction 2,560 (incl. Oxymorphone)
Taking anything else?

Check Another of Your Medications Against Gamma Butyrolactone (gbl)

Covers the 2,830 medications we’ve checked against Gamma Butyrolactone (gbl). Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Oxymorphone

This page covers Gamma Butyrolactone (gbl) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Oxymorphone page lists 100 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 7 major · 78 moderate · 15 minor.

Open the Oxymorphone interaction page

How much people look this up

Where Gamma Butyrolactone (gbl) and Oxymorphone Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Gamma Butyrolactone (gbl)
Steady interest

#1,195 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Oxymorphone
Top half

#1,122 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Gamma Butyrolactone (gbl)

What is Gamma Butyrolactone (gbl)?

Gamma Butyrolactone (gbl)
  • Recreational intoxication and euphoria
  • Relaxation and sedation
  • Sleep aid (misused)
  • Bodybuilding/muscle building claims (unproven)
  • Industrial solvent and cleaner

Gamma butyrolactone (GBL) is a toxic industrial solvent, not a dietary supplement, and the body converts it into GHB, a powerful and dangerous sedative. It is illegal to sell or possess for human use in the United States, has no proven medical or supplemental benefit, and can cause coma, seizures, and death. Do not take GBL — if you are seeking help for sleep, anxiety, or substance use, talk to a doctor or pharmacist.

Read the full Gamma Butyrolactone (gbl) monograph & all interactions
Medication

About Oxymorphone

What Is Oxymorphone Used For?

Brand names: Numorphan, Opana, Opana ER, Opana Injection

Oxymorphone Hydrochloride Tablets (immediate-release) are used to treat acute pain severe enough to require an opioid when other pain treatments are not enough. Oxymorphone Hydrochloride Extended-Release Tablets are used to manage severe, persistent pain that needs to be treated with a daily opioid over an extended period and when other options are inadequate.

Both forms are reserved for situations where non-opioid medicines or other approaches have not worked well enough. Oxymorphone Hydrochloride Extended-Release Tablets are not meant to be taken on an as-needed basis — they are for ongoing, around-the-clock pain management only.

See full Oxymorphone drug information
Keep checking

Other Drugs & Gamma Butyrolactone (gbl)

Browse every other medication we’ve checked against Gamma Butyrolactone (gbl) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
270Moderate
0Minor
2,559No known interaction
270 Moderate 2,559 No interaction
Moderate

270 interactions

Showing 60 of 270 moderate interactions — see all 270 on the Gamma Butyrolactone (gbl) page.

No interaction 2,559 drugs checked — show the list

We also checked Gamma Butyrolactone (gbl) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,559 medications checked with no known interaction — see the full Gamma Butyrolactone (gbl) list.

See the full Gamma Butyrolactone (gbl) interactions page
See every supplement checked against Oxymorphone, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

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.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Gamma Butyrolactone (gbl) monograph › Uses, safety, and every drug interaction in one place Oxymorphone supplement interactions › Every supplement checked against Oxymorphone, ranked by severity Oxymorphone drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Gamma Butyrolactone (gbl) and Oxymorphone Together: Common Questions

Can you take Gamma Butyrolactone (gbl) with Oxymorphone?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Gamma Butyrolactone (gbl) and Oxymorphone?
Oxymorphone belongs to more than one drug category, and Gamma Butyrolactone (gbl) interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Gamma Butyrolactone (gbl) and Oxymorphone interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Oxymorphone and Gamma Butyrolactone (gbl)?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.