Goldenseal + Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine
Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine brand name: Conar-A.
Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine falls into 4 drug categories that Goldenseal can interact with; the most serious is rated moderate. Goldenseal might increase serum levels of drugs metabolized by CYP2D6.
Read the full interaction reportGoldenseal and Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine
These two interact in 4 distinct ways. Each one is explained separately below.
Why Are There 4 Interactions?
Goldenseal interacts with whole categories of medication. Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine falls into 4 of those categories, so it can interact with Goldenseal in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).
CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES
1 of 4Why this applies to Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine
Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Goldenseal interacts with.
Clinical and in vitro research shows that goldenseal can significantly inhibit CYP2D6 enzymes, potentially increasing levels of drugs metabolized by CYP2D6.
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..
In this combination cough and cold product, the ingredient that matters here is the dextromethorphan (the cough suppressant). Your body relies on an enzyme called CYP2D6 to break it down. Goldenseal can slow that enzyme, so dextromethorphan may clear more slowly and build up in your blood. The acetaminophen, guaifenesin, and phenylephrine pieces aren't really affected by this particular interaction.
With more dextromethorphan hanging around, you might feel more drowsy, dizzy, or lightheaded than usual, and in higher amounts it can cause restlessness or confusion. The evidence for this is fairly solid, though the effect is usually moderate. Concentrated goldenseal supplements are the concern, not occasional food amounts. Before pairing them, please check with your pharmacist or doctor first.
- Gurley BJ, Gardner SF, Hubbard MA, et al. In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes. Clin Pharmacol Ther 2005;77:415-26. PubMed
- Gurley BJ, Swain A, Hubbard MA, et al. Clinical assessement of CYP2D6-mediated herb-drug interactions in humans: Effects of milk-thistle, black cohosh, goldenseal, kava kava, St. John's wort, and Echinacea. Mol Nutr Food Res 2008;52:755-63.
- Sevior, D. K., Hokkanen, J., Tolonen, A., Abass, K., Tursas, L., Pelkonen, O., and Ahokas, J. T. Rapid screening of commercially available herbal products for the inhibition of major human hepatic cytochrome P450 enzymes using the N-in-one cocktail. Xeno PubMed
CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES
2 of 4Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.
Most clinical and in vitro research shows that goldenseal inhibits CYP3A4 enzyme activity and increases serum levels of CYP3A4 substrates, such as midazolam. However, in one small clinical study, goldenseal did not affect the levels of indinavir, a CYP3A4 substrate, in healthy volunteers. This is likely due to the fact that indinavir has a high oral bioavailability, making it an inadequate probe for CYP3A4 interactions and/or that it is primarily metabolized by hepatic CYP3A, while goldenseal has more potential to inhibit intestinal CYP3A enzyme activity. Both goldenseal extract and its isolated constituents berberine and hydrastine inhibit CYP3A, with hydrastine possibly having more inhibitory potential than berberine.
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.
This combo cold product has a few parts, but the one that matters here is dextromethorphan, the cough suppressant. Goldenseal can block the CYP3A4 enzyme that helps your body clear it. When that pathway slows down, dextromethorphan can build up a bit higher than usual, which may bring on more drowsiness, dizziness, or a foggy, lightheaded feeling.
The other ingredients (acetaminophen, guaifenesin, and phenylephrine) aren't mainly handled by this enzyme, so they're less of a concern here. This interaction is rated moderate and is only possible, based on limited human research, so I wouldn't panic. Still, if you take goldenseal regularly and reach for this cold medicine, give your pharmacist or doctor a quick call before combining them.
- Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
- Sandhu RS, Prescilla RP, Simonelli TM, Edwards DJ. Influence of goldenseal root on the pharmacokinetics of indinavir. J Clin Pharmacol 2003;43:1283-8.. PubMed
- Gurley BJ, Gardner SF, Hubbard MA, et al. In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes. Clin Pharmacol Ther 2005;77:415-26. PubMed
- Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
- Gurley BJ, et al. Supplementation with goldenseal (Hydrastis canadensis), but not kava kava (Piper methysticum), inhibits human CYP3A activitiy In Vivo. Clin Pharmacol Ther. 2008;83(1):61-69.
- Jalloh MA, Gregory PJ, Hein D, et al. Dietary supplement interactions with antiretrovirals: a systematic review. Int J STD AIDS. 2017 Jan;28(1):4-15. PubMed
- Nguyen JT, Tian DD, Tanna RS, et al. An Integrative Approach to Elucidate Mechanisms Underlying the Pharmacokinetic Goldenseal-Midazolam Interaction: Application of In Vitro Assays and Physiologically Based Pharmacokinetic Models to Understand Clinical Ob
CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES
3 of 4Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine also falls under CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES.
In vitro research shows that goldenseal root extract can inhibit the activity of CYP2E1. However, this effect has not been reported in humans.
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.
This combination cold-and-cough product (Conar-A) has one ingredient worth flagging here: acetaminophen. The body uses an enzyme called CYP2E1 to handle a small part of acetaminophen, and lab dish studies hint that goldenseal might slow that enzyme down. In theory, slowing it could shift how acetaminophen is processed. The honest truth is this has only been seen in test tubes, never confirmed in people, so I wouldn't lose sleep over it.
Still, acetaminophen is the one ingredient where overdoing it can stress the liver, so a sensible move is to stay within the labeled dose and avoid extra acetaminophen from other products. If you take goldenseal regularly, just mention it to your pharmacist so they can double-check your full medication list.
- Yamaura K, Shimada M, Nakayama N, Ueno K. Protective effects of goldenseal (Hydrastis canadensis L.) on acetaminophen-induced hepatotoxicity through inhibition of CYP2E1 in rats. Pharmacognosy Res. 2011;3(4):250-5. PubMed
DEXTROMETHORPHAN (Robitussin DM, others)
4 of 4Goldenseal contains berberine. A small clinical study shows that berberine can inhibit cytochrome P450 2D6 (CYP2D6) activity and reduce the metabolism of dextromethorphan.
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.
This combo cold product contains dextromethorphan, the cough suppressant, and that is the piece goldenseal could nudge. Your body clears dextromethorphan using a liver enzyme called CYP2D6. The berberine in goldenseal can slow that enzyme down, so in theory more dextromethorphan hangs around in your blood. That can mean stronger side effects like drowsiness, dizziness, or feeling foggy, lightheaded, or jittery.
I want to be honest about the evidence here: this is mostly theoretical, based on how the compounds behave, plus one small study. For most people taking a short course of a cough and cold medicine, it is unlikely to cause real trouble, and the other ingredients (acetaminophen, guaifenesin, phenylephrine) are not the concern. Still, if you use concentrated goldenseal supplements, mention it to your pharmacist before combining them.
- Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
What These Ratings Mean
Every interaction above is graded three ways — here’s the key to each label.
Clinically significant. Avoid the combination, or use only under close professional supervision.
Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.
Generally not serious. Be aware of it and mention it to your pharmacist.
- 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.
- 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.
Goldenseal Also Interacts With Other Medications
Goldenseal has 1,235 moderate, 1 minor known drug interactions in our database — the Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine one above is among them. If you take anything else, check it against the full list below.
Check Another of Your Medications Against Goldenseal
We haven’t checked that one against Goldenseal yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against Goldenseal. Pick one to open its full report.
See Every Supplement That Interacts With Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine
This page covers Goldenseal only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine page lists 261 supplements it has a documented interaction with, worst first, each one explained.
The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Ephedra (major) and Grapefruit (major).
By severity: 12 major · 206 moderate · 43 minor.
From our pharmacist’s overview on the Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine page
“Picture the week someone takes Conar-A (acetaminophen, dextromethorphan, guaifenesin, phenylephrine): a miserable cold, coffee to push through, maybe wine at night or an herbal remedy on top. Those habits are exactly where this list turns serious.”
Reviewed by 2 · Jul 18, 2026
Open the Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine interaction page
Taking Goldenseal as Part of a Dietary Supplement Product? Check It for Interactions
We hold 1,726 real supplement products containing Goldenseal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Goldenseal. Your product may carry other ingredients that interact with Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine too, on top of Goldenseal — and those would not show on this page. Find your product and we’ll check every ingredient on its label:
Where Goldenseal and Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine 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.
#155 of 1,452 supplements looked up here in the last 7 days
#981 of 2,830 medications looked up here in the last 7 days
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.
About Goldenseal
What is Goldenseal?
- Digestive upset and diarrhea
- Colds and respiratory infections
- Sore throat and mouth sores
- Skin and eye irritation (topical/traditional)
- Antimicrobial support
Goldenseal is a popular North American herb that contains berberine, a compound studied for antimicrobial effects. However, strong human evidence for its many traditional uses is largely lacking, and it should be avoided during pregnancy and breastfeeding. Talk to a pharmacist or doctor before using it.
Other Drugs & Goldenseal
Browse every other medication we’ve checked against Goldenseal — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
1,235 interactions
- Diclofenac Sodium ›
- Diltiazem ›
- Nifedipine ›
- Ibuprofen ›
- Diphenhydramine ›
- Aspirin ›
- Hydrocortisone ›
- Insulin (rdna) ›
- Naproxen ›
- Doxycycline ›
- Erythromycin ›
- Estradiol ›
- Minocycline ›
- Propranolol ›
- Tetracycline ›
- Lidocaine ›
- Ranitidine ›
- Guaifenesin ›
- Hydrochlorothiazide ›
- Norethindrone ›
- Testosterone ›
- Verapamil ›
- Levonorgestrel ›
- Prednisone ›
- Quinidine ›
- Cyclosporine ›
- Dexamethasone ›
- Flurazepam ›
- Glyburide ›
- Insulin (pork) ›
- Triazolam ›
- Zopiclone ›
- Colchicine ›
- Fentanyl ›
- Flurbiprofen ›
- Oxybutynin ›
- Oxycodone ›
- Phenytoin ›
- Prednisolone ›
- Tacrolimus ›
- Temazepam ›
- Triamcinolone ›
- Apomorphine ›
- Budesonide ›
- Carbamazepine ›
- Clindamycin ›
- Dextromethorphan ›
- Diclofenac Potassium ›
- Dipyridamole ›
- Doxorubicin ›
- Fluticasone ›
- Formoterol ›
- Hydralazine ›
- Indomethacin ›
- Insulin (human) ›
- Miconazole ›
- Morphine Sulfate ›
- Nitrazepam ›
- Trimipramine ›
- Acetaminophen ›
Showing 60 of 1,235 moderate interactions — see all 1,235 on the Goldenseal page.
1 interaction
No interaction 1,593 drugs checked — show the list
We also checked Goldenseal against these medications and found no known interaction in our sources. Open any page to confirm.
- Levothyroxine ›
- Methylphenidate ›
- Rosuvastatin ›
- Escitalopram ›
- Docusate ›
- Hydroxyurea ›
- Valacyclovir ›
- Sumatriptan ›
- Amoxicillin ›
- Bupropion ›
- Bendamustine ›
- Acyclovir ›
- Methotrexate ›
- Azithromycin ›
- Isotretinoin ›
- Methylene Blue ›
- Ciprofloxacin ›
- Levothyroxine, Liothyronine ›
- Cephalexin ›
- Cyclopentolate ›
- Roxithromycin ›
- Pegunigalsidase Alfa-iwxj ›
- Ezetimibe ›
- Daptomycin ›
- Levothyroxine Sodium ›
- Dexmethylphenidate ›
- Amoxicillin, Clavulanate Potassium ›
- Hexobarbitone ›
- Thyroid Hormone ›
- Carbidopa, Levodopa ›
- Factor 7a ›
- Levodopa ›
- Hethylphenidate Hcl ›
- Mitomycin ›
- Lenvatinib ›
- Cefaclor ›
- Azelaic Acid ›
- Phenylephrine ›
- Hydroxychloroquine ›
- Dirithromycin ›
- Pizotifen ›
- Vancomycin ›
- Triptorelin ›
- Bentoquatam ›
- Dextrothyroxine ›
- Procainamide ›
- Ropinirole ›
- Tocainide ›
- Rocuronium ›
- Mitomycin C ›
- Lomustine ›
- Digitoxin ›
- Chenodiol ›
- Salbutamol Sulfate ›
- Gestodene ›
- Desflurane ›
- Caspofungin ›
- Flutemetamol F-18 ›
- Niacin (prescription Drug) ›
- Halothane ›
Showing the 60 most looked-up of 1,593 medications checked with no known interaction — see the full Goldenseal list.
Sources & How We Checked
Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for vitamins, herbs and supplements — the basis for our interaction data.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for the medication overviews.
- NIH Dietary Supplement Label Database (DSLD) — Official supplement product labels.
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
Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine Is Linked to Lower Levels of One Nutrient
Natural Medicines records Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine as a medicine that can lower these. This is not an interaction with Goldenseal — it is a separate effect of the medicine, and it is a reason some people are advised to supplement rather than to avoid one:
Depletion records come from the licensed Natural Medicines database. Do not start a supplement on the strength of this page — ask your pharmacist or doctor whether it applies to you.
Taking Goldenseal and Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine Together: Common Questions
Can you take Goldenseal with Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine?
Why are there 4 interactions listed for Goldenseal and Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine?
How serious is the Goldenseal and Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine interaction?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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