Drug & supplement interaction

Gamma Butyrolactone (gbl) + Macitentan

Macitentan brand name: Opsumit.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Gamma Butyrolactone (gbl) and Macitentan in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Gamma Butyrolactone (gbl) and Macitentan

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Macitentan and Gamma Butyrolactone (gbl) in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Gamma Butyrolactone (gbl) safety at a glance

Gamma Butyrolacton... overall Avoid GBL is a toxic, illegal substance that can cause coma and death; it should never be consumed.
Pregnancy Unsafe When used orally; avoid using. Read the full pregnancy detail
Breastfeeding Unsafe When used orally; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Macitentan and Gamma Butyrolactone (gbl)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Macitentan

Interactions in our licensed database are recorded against drug classes, not just single drug names. Macitentan is filed under 4 classifications — including antihypertensive drugs, hepatotoxic drugs, cytochrome p450 3a4 (cyp3a4) substrates. Gamma Butyrolactone (gbl) has documented interactions with 10 drug classes — the most serious being alcohol (ethanol) (moderate), amphetamines (moderate) and anticonvulsants (moderate) — and none of Macitentan’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Gamma Butyrolactone (gbl) Does Interact With Other Medications

Gamma Butyrolactone (gbl) has 271 moderate known drug interactions in our database — Macitentan isn’t one of them. If you take anything else, check it against the full list below.

Moderate 271 No known interaction 2,559 (incl. Macitentan)
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.

What to actually watch for

No Interaction Found — But Data Suggests Gamma Butyrolactone (gbl) and Macitentan May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • A higher chance of infection Worth acting on Additional detail

    Gamma Butyrolactone (gbl)

    “Orally, GBL can cause slow breathing and respiratory depression resulting in cyanosis, apnea, and hypoxia, possibly requiring intubation. In one case report, a 44-year-old female developed acute lung injury, or chemical pneumonitis, with bilateral alveolar inflammatory consolidations after chronic ingestion of GBL. Infectious sources were ruled out.”

    Gamma Butyrolactone (gbl) · Natural Medicines adverse-effect record, reported in depression.

    6 sources cited
    1. 665. LoVecchio F, Curry SC, Bagnasco T. Butyrolactone-induced central nervous system depression after ingestion of RenewTrient, a dietary supplement. N Engl J Med 1998;339:847-8.
    2. 682. FDA. FDA warns about products containing gamma butyrolactone or GBL and asks companies to issue a recall. Talk Paper, 21 January 1999.
    3. 1430. Anon. Adverse events associated with ingestion of gamma-butyrolactone--Minnesota, New Mexico, and Texas, 1998-1999. MMWR Morb Mortal Wkly Rep 1999;48:137-40.
    4. 4259. FDA Talk Paper. FDA Warns About GBL-Related Products. 1999. Available at: vm.cfsan.fda.gov/~lrd/tpgbl2.html
    5. 95118. Bhattacharya IS, Watson F, Bruce M. A case of ?-butyrolactone associated with severe withdrawal delirium and acute renal failure. Eur Addict Res 2011;17(4):169-71. PubMed
    6. 95127. Corkery JM, Loi B, Claridge H, et al. Gamma hydroxybutyrate (GHB), gamma butyrolactone (GBL) and 1,4-butanediol (1,4-BD; BDO): A literature review with a focus on UK fatalities related to non-medical use. Neurosci Biobehav Rev 2015;53:52-78. PubMed

    Macitentan

    Listed in the ADVERSE REACTIONS section of the FDA label for Macitentan. Read the label on DailyMed ›

  • Low blood pressure Additional detail

    Gamma Butyrolactone (gbl)

    “Orally, GBL can cause bradycardia, hypotension, tachycardia, and cardiac arrest.

    Consistent use of GBL followed by abrupt discontinuation is associated with withdrawal symptoms, including tachycardia and hypertension.”

    Gamma Butyrolactone (gbl) · Natural Medicines adverse-effect record, reported in cardiac arrest.

    6 sources cited
    1. 665. LoVecchio F, Curry SC, Bagnasco T. Butyrolactone-induced central nervous system depression after ingestion of RenewTrient, a dietary supplement. N Engl J Med 1998;339:847-8.
    2. 682. FDA. FDA warns about products containing gamma butyrolactone or GBL and asks companies to issue a recall. Talk Paper, 21 January 1999.
    3. 1430. Anon. Adverse events associated with ingestion of gamma-butyrolactone--Minnesota, New Mexico, and Texas, 1998-1999. MMWR Morb Mortal Wkly Rep 1999;48:137-40.
    4. 95127. Corkery JM, Loi B, Claridge H, et al. Gamma hydroxybutyrate (GHB), gamma butyrolactone (GBL) and 1,4-butanediol (1,4-BD; BDO): A literature review with a focus on UK fatalities related to non-medical use. Neurosci Biobehav Rev 2015;53:52-78. PubMed
    5. 95128. Dargan PI, Button J, Davies S, et al. The first reported UK fatality related to gamma-butyrolactone (GBL) ingestion. J R Soc Med 2009;102(12):546-7.
    6. 95130. Heytens L, Neels H, Van Regenmortel N, et al. Near-fatal persistent anion- and osmolal-gap acidosis due to massive gamma-butyrolactone/ethanol intoxication. Ann Clin Biochem 2015;52(Pt 2):283-7. PubMed

    Macitentan

    Listed in the ADVERSE REACTIONS section of the FDA label for Macitentan. Read the label on DailyMed ›

  • Swelling Additional detail

    Gamma Butyrolactone (gbl)

    Recorded for Gamma Butyrolactone (gbl) in the same Natural Medicines adverse-effect record shown under Low blood pressure above.

    Macitentan

    Listed in the ADVERSE REACTIONS section of the FDA label for Macitentan. Read the label on DailyMed ›

Reported for Gamma Butyrolactone (gbl) but not commonly for Macitentan: dependence or withdrawal symptoms, kidney problems, sweating and hallucinations.

Effects for Macitentan come from the ADVERSE REACTIONS section of its FDA label; effects for Gamma Butyrolactone (gbl) come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Gamma Butyrolactone (gbl) in Pregnancy & Breastfeeding

Pregnancy And Lactation Unsafe

When used orally; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Everything else you take

See Every Supplement That Interacts With Macitentan

This page covers Gamma Butyrolactone (gbl) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Macitentan page lists 253 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Beer (major) and Grapefruit (major).

By severity: 9 major · 205 moderate · 39 minor.

From our pharmacist’s overview on the Macitentan page

“If you take macitentan (Opsumit) for pulmonary arterial hypertension, study this page rather than skim it. It lists 253 supplement and herbal ingredients, nine rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Macitentan interaction page

How much people look this up

Where Gamma Butyrolactone (gbl) and Macitentan 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

#1,208 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Macitentan
Top 25%

#328 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Gamma Butyrolactone (gbl) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Gamma Butyrolactone (gbl) and Macitentan records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
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.

Not applicable (synthetic industrial chemical) · Liquid (illicitly sold); used industrially as a solvent

An interaction check asks whether these two react with each other — it does not ask whether Gamma Butyrolactone (gbl) is a good idea for someone in your situation. Here is what our Gamma Butyrolactone (gbl) record says about it on its own.

Gamma Butyrolactone (gbl): dosing

There is no safe or recommended dose of GBL. It is not a supplement, it is illegal to sell for human use, and any amount can be dangerous because it converts into the potent sedative GHB.No pharmacist or doctor should recommend taking GBL.

From our Gamma Butyrolactone (gbl) monograph — the full record covers uses, side effects and every documented interaction.

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

About Macitentan

What Is Macitentan Used For?

Brand name: Opsumit

Macitentan tablets — sold under the brand name Opsumit — are used to treat pulmonary arterial hypertension (PAH, WHO Group I), a serious condition where the blood pressure in the arteries supplying the lungs is abnormally high. The goal is to slow down how quickly the disease gets worse and to lower the chances of being hospitalized because of it.

In clinical studies, it was shown to be effective in adults with mostly moderate-to-severe PAH symptoms. Patients in those studies had PAH caused by unknown or inherited reasons, connective tissue disorders, or congenital heart disease with repaired heart shunts.

See full Macitentan 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
271Moderate
0Minor
2,558No known interaction
271 Moderate 2,558 No interaction
Moderate

271 interactions

Showing 60 of 271 moderate interactions — see all 271 on the Gamma Butyrolactone (gbl) page.

No interaction 2,558 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 2,558 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 Macitentan, ranked by severity
Evidence & sources

Gamma Butyrolactone (gbl) References

The 28 references that drive our Gamma Butyrolactone (gbl) monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Soderling E, Le Bell A, Kirstila V, Tenovuo J. Betaine-containing toothpaste relieves subjective symptoms of dry mouth. Acta Odontol Scand 1998;56:65-9.
  2. LoVecchio F, Curry SC, Bagnasco T. Butyrolactone-induced central nervous system depression after ingestion of RenewTrient, a dietary supplement. N Engl J Med 1998;339:847-8.
  3. FDA. FDA warns about products containing gamma butyrolactone or GBL and asks companies to issue a recall. Talk Paper, 21 January 1999.
  4. Anon. Adverse events associated with ingestion of gamma-butyrolactone--Minnesota, New Mexico, and Texas, 1998-1999. MMWR Morb Mortal Wkly Rep 1999;48:137-40.
  5. Harrington RD, Woodward JA, Hooton TM, et al. Life-threatening interactions between HIV-1 protease inhibitors and the illicit drugs MDMA and gamma-hydroxybutyrate. Arch Intern Med 1999;159:2221-4.
  6. Anon. FDA alert on misuse of consumer products containing GHB, GBL and BD. Food and Drug Administration, Rockville, MD. June 15, 1999.
  7. 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
  8. Anon. Multistate outbreak of poisonings associated with illicit use of gamma hydroxy butyrate. JAMA 1991;265:447-8. DOI
  9. Carotenuto A, De Feo V, Fattorusso E, et al. The flavonoids of Allium ursinum. Phytochem 1996;41:531-6. PubMed
  10. FDA Talk Paper. FDA Warns About GBL-Related Products. 1999. Available at: vm.cfsan.fda.gov/~lrd/tpgbl2.html
  11. 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
  12. Schneir AB, Ly BT, Clark RF. A case of withdrawal from the GHB precursors gamma-butyrolactone and 1,4-butanediol. J Emerg Med 2001;21:31-3.. PubMed
  13. Sivilotti ML, Burns MJ, Aaron CK, Greenberg MJ. Pentobarbital for severe gamma-butyrolactone withdrawal. Ann Emerg Med 2001;38:660-5.. PubMed
  14. Bosch OG, Eisenegger C, Gertsch J, et al. Gamma-hydroxybutyrate enhances mood and prosocial behavior without affecting plasma oxytocin and testosterone. Psychoneuroendocrinology. 2015 Dec;62:1-10. PubMed
  15. Thai D, Dyer JE, Benowitz NL, Haller CA. Gamma-hydroxybutyrate and ethanol effects and interactions in humans. J Clin Psychopharmacol. 2006 Oct;26(5):524-9. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

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

Is it safe to take Gamma Butyrolactone (gbl) with Macitentan?
We do not list a known interaction between Gamma Butyrolactone (gbl) and Macitentan. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Gamma Butyrolactone (gbl) and Macitentan have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Gamma Butyrolactone (gbl) and Macitentan combination checked?
Interactions in our licensed database are recorded against drug classes. Macitentan is filed under 4 classifications, and Gamma Butyrolactone (gbl) has documented interactions with 10 drug classes — none of Macitentan's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Gamma Butyrolactone (gbl) interact with any other medications?
Yes. Gamma Butyrolactone (gbl) has 271 documented drug interactions in our database — Macitentan is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Macitentan interact with any supplements?
Yes. Macitentan has documented interactions with 253 supplements in our database — Gamma Butyrolactone (gbl) is not one of them. The Macitentan interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Gamma Butyrolactone (gbl) monograph Uses, safety profile, and every drug interaction in one place Macitentan drug information The full plain-English guide to this medication Macitentan supplement interactions Every supplement checked against Macitentan, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 28 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.