Drug & supplement interaction

Gamma-hydroxybutyrate (ghb) + Codeine Phosphate, Guaifenesin

Codeine Phosphate, Guaifenesin brand names: Brontex, Robitussin AC.

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

Gamma-hydroxybutyrate (ghb) has a major interaction with Codeine Phosphate, Guaifenesin. GHB may increase the risk of serious CNS and respiratory depression.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Gamma-hydroxybutyrate (ghb) and Codeine Phosphate, Guaifenesin

Here is the interaction we found between these two, with the evidence behind it.

Major

CNS DEPRESSANTS

Why this applies to Codeine Phosphate, Guaifenesin

Codeine Phosphate, Guaifenesin falls under CNS DEPRESSANTS — the group Gamma-hydroxybutyrate (ghb) interacts with.

GHB may increase the risk of serious CNS and respiratory depression.
Concomitant use of GHB with CNS depressants may increase the risk of serious CNS and respiratory depression.
Severity Major Likelihood Probable Evidence D

Interaction 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..

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

Here's the big concern with this pairing: both GHB and the codeine in your cough syrup slow down the same systems in your body. The codeine part is an opioid, so it already calms breathing and makes you drowsy. GHB is a powerful brain depressant that does the very same thing. Stacking two depressants like this can pile up faster than either one alone.

Together they can lead to heavy sedation, slowed or shallow breathing, very low alertness, and in serious cases loss of consciousness or stopped breathing. This isn't about the guaifenesin, which is just a mucus-thinner. The evidence here is mostly anecdotal, but the risk is real enough that I'd urge you to talk with your doctor or pharmacist before combining these. Honestly, non-prescription GHB isn't a safe product to be using at all.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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-hydroxybutyrate (ghb) Also Interacts With Other Medications

Gamma-hydroxybutyrate (ghb) has 248 major, 21 moderate, 5 minor known drug interactions in our database — the Codeine Phosphate, Guaifenesin one above is one of them. If you take anything else, check it against the full list below.

Major 248 Moderate 21 Minor 5 No known interaction 2,556 (incl. Codeine Phosphate, Guaifenesin)
Taking anything else?

Check Another of Your Medications Against Gamma-hydroxybutyrate (ghb)

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

Everything else you take

See Every Supplement That Interacts With Codeine Phosphate, Guaifenesin

This page covers Gamma-hydroxybutyrate (ghb) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Codeine Phosphate, Guaifenesin page lists 144 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), Kava (major) and L-tryptophan (major).

By severity: 7 major · 114 moderate · 23 minor.

Open the Codeine Phosphate, Guaifenesin interaction page

How much people look this up

Where Gamma-hydroxybutyrate (ghb) and Codeine Phosphate, Guaifenesin 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-hydroxybutyrate (ghb)
Steady interest

#1,265 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Codeine Phosphate, Guaifenesin
Top 25%

#365 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-hydroxybutyrate (ghb)

What is Gamma-hydroxybutyrate (ghb)?

  • Narcolepsy (cataplexy and excessive daytime sleepiness)
  • Sleep aid
  • Misused as a recreational 'party drug'
  • Bodybuilding/muscle building (unproven)
  • Alcohol withdrawal (in some countries)

GHB (gamma-hydroxybutyrate) is a powerful central nervous system depressant that is NOT a safe dietary supplement. In the U.S. it is a controlled substance, and only a tightly regulated prescription form (sodium oxybate) is legal for narcolepsy. Non-prescription GHB can cause coma, breathing failure, and death, and it is also a known 'date-rape' drug — it should not be taken outside of medical supervision.

Read the full Gamma-hydroxybutyrate (ghb) monograph & all interactions
Keep checking

Other Drugs & Gamma-hydroxybutyrate (ghb)

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

248Major
21Moderate
5Minor
2,555No known interaction
248 Major 21 Moderate 5 Minor 2,555 No interaction
Major

248 interactions

Showing 60 of 248 major interactions — see all 248 on the Gamma-hydroxybutyrate (ghb) page.

Moderate

21 interactions

Minor

5 interactions

No interaction 2,555 drugs checked — show the list

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

Showing the 60 most looked-up of 2,555 medications checked with no known interaction — see the full Gamma-hydroxybutyrate (ghb) list.

See the full Gamma-hydroxybutyrate (ghb) interactions page
See every supplement checked against Codeine Phosphate, Guaifenesin, 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-hydroxybutyrate (ghb) monograph › Uses, safety, and every drug interaction in one place Codeine Phosphate, Guaifenesin supplement interactions › Every supplement checked against Codeine Phosphate, Guaifenesin, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Gamma-hydroxybutyrate (ghb) and Codeine Phosphate, Guaifenesin Together: Common Questions

Can you take Gamma-hydroxybutyrate (ghb) with Codeine Phosphate, Guaifenesin?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Gamma-hydroxybutyrate (ghb) and Codeine Phosphate, Guaifenesin interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Codeine Phosphate, Guaifenesin and Gamma-hydroxybutyrate (ghb)?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.