Drug & supplement interaction

Goji + Dextromethorphan, Guaifenesin

Dextromethorphan, Guaifenesin brand names: Sudal DM, Touro DM, Queltuss, Fenesin DM, Monafed DM, and others.

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

Dextromethorphan, Guaifenesin falls into 2 drug categories that Goji can interact with; the most serious is rated moderate. Theoretically, goji berry might inhibit CYP2D6 and reduce metabolism of CYP2D6 substrates.

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

Goji and Dextromethorphan, Guaifenesin

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

Why Are There 2 Interactions?

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

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

1 of 2

Why this applies to Dextromethorphan, Guaifenesin

Dextromethorphan, Guaifenesin falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Goji interacts with.

Theoretically, goji berry might inhibit CYP2D6 and reduce metabolism of CYP2D6 substrates.
In vitro research shows that goji berry juice inhibits CYP2D6 enzymes. Concomitant use with goji may decrease metabolism and increase levels of CYP2D6 substrates. However, this has not been reported in humans.
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

Here's the gist with this combo. The cough suppressant part, dextromethorphan, gets cleared from your body by a liver enzyme called CYP2D6. In lab dishes, goji berry juice has been shown to slow that same enzyme down. If that held true in people, your body might clear dextromethorphan a little slower, letting it build up. That could mean more drowsiness, dizziness, or a foggy, lightheaded feeling. The guaifenesin (the mucus thinner) isn't really affected here.

The reassuring part: this is only test-tube evidence and has never actually been reported in real patients. Eating goji berries as a food is very unlikely to cause trouble. Still, if you're using concentrated goji supplements, it's worth a quick chat with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu R, Tam TW, Mao J, et al. In vitro activity of Lycium barbarum (Goji) against major human phase I metabolism enzymes. Complement Integr Med. 2016;13(3):257-265.
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Dextromethorphan, Guaifenesin also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, goji berry might inhibit CYP3A4 and reduce metabolism of CYP3A4 substrates.
In vitro research shows that goji berry juice inhibits CYP3A4 enzymes. Concomitant use with goji may decrease metabolism and increase levels of CYP3A4 substrates. However, this has not been reported in humans.
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

Here's the short version on combining goji with a cough syrup like Sudal DM. Dextromethorphan (the cough suppressant) is partly cleared by a liver enzyme called CYP3A4. In lab studies, goji berry juice appears to slow that enzyme down. If that happened in real life, dextromethorphan could build up a bit, which might mean more drowsiness, dizziness, or feeling foggy. The guaifenesin part isn't really affected this way.

The key thing: this is only test-tube evidence and hasn't actually shown up in people. Eating goji berries as food is very unlikely to cause trouble. If you're using strong, concentrated goji supplements, just run it by your pharmacist or doctor first to be safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu R, Tam TW, Mao J, et al. In vitro activity of Lycium barbarum (Goji) against major human phase I metabolism enzymes. Complement Integr Med. 2016;13(3):257-265.

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

Goji Also Interacts With Other Medications

Goji has 2 major, 929 moderate, 68 minor known drug interactions in our database — the Dextromethorphan, Guaifenesin one above is among them. If you take anything else, check it against the full list below.

Major 2 Moderate 929 Minor 68 No known interaction 1,831 (incl. Dextromethorphan, Guaifenesin)
Taking anything else?

Check Another of Your Medications Against Goji

Covers the 2,830 medications we’ve checked against Goji. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Dextromethorphan, Guaifenesin

This page covers Goji only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dextromethorphan, Guaifenesin page lists 171 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Lithium (major), St. John's Wort (major) and 1,3-dmaa (moderate).

By severity: 4 major · 125 moderate · 42 minor.

From our pharmacist’s overview on the Dextromethorphan, Guaifenesin page

“Dextromethorphan with guaifenesin (Sudal DM, Touro DM, Queltuss, and others) sounds too ordinary a cough medicine to tangle badly with supplements, yet 4 of the 171 ingredients on this list rate major and belong at the top of your reading. Grapefruit and St.”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan, Guaifenesin interaction page

One more smart check

Taking Goji as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,738 real supplement products containing Goji, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Goji. Your product may carry other ingredients that interact with Dextromethorphan, Guaifenesin too, on top of Goji — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Goji and Dextromethorphan, 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 Goji
Top 10%

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

29 days ago today
Medication Dextromethorphan, Guaifenesin
Steady interest

#2,317 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 Goji

What is Goji?

Goji
  • General antioxidant support
  • Eye health
  • Immune support
  • Anti-aging and well-being
  • Blood sugar support

Goji berries are a nutritious fruit rich in antioxidants, vitamins, and plant polysaccharides, and they are safe for most people as a food. While they are popular for eye health, immune support, and general wellness, strong human evidence for most health claims is limited. Talk with your pharmacist or doctor before using concentrated goji supplements, especially if you take medications or are pregnant.

Read the full Goji monograph & all interactions
Keep checking

Other Drugs & Goji

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

2Major
929Moderate
68Minor
1,830No known interaction
2 Major 929 Moderate 68 Minor 1,830 No interaction
Major

2 interactions

Moderate

929 interactions

Showing 60 of 929 moderate interactions — see all 929 on the Goji page.

Minor

68 interactions

Showing 60 of 68 minor interactions — see all 68 on the Goji page.

No interaction 1,830 drugs checked — show the list

We also checked Goji against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,830 medications checked with no known interaction — see the full Goji list.

See the full Goji interactions page
See every supplement checked against Dextromethorphan, 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
Goji monograph › Uses, safety, and every drug interaction in one place Dextromethorphan, Guaifenesin supplement interactions › Every supplement checked against Dextromethorphan, 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 Goji and Dextromethorphan, Guaifenesin Together: Common Questions

Can you take Goji with Dextromethorphan, Guaifenesin?
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 Goji and Dextromethorphan, Guaifenesin?
Dextromethorphan, Guaifenesin belongs to more than one drug category, and Goji 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 Goji and Dextromethorphan, Guaifenesin 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

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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.