Ayahuasca + Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine
Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine brand name: Colrex.
Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls into 3 drug categories that Ayahuasca can interact with; the most serious is rated moderate. Theoretically, ayahuasca might increase levels of serotonin, which may have additive effects with serotonergic drugs.
Read the full interaction reportAyahuasca and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine
These two interact in 3 distinct ways. Each one is explained separately below.
Why Are There 3 Interactions?
Ayahuasca interacts with whole categories of medication. Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls into 3 of those categories, so it can interact with Ayahuasca in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).
SEROTONERGIC DRUGS
1 of 3Why this applies to Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine
Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine falls under SEROTONERGIC DRUGS — the group Ayahuasca interacts with.
In vitro and animal research shows that harmaline and harmine, constituents of ayahuasca, strongly and reversibly inhibit monoamine oxidase A and weakly inhibit monoamine oxidase B. The dimethyltryptamine and tetrahydroharmine constituents of ayahuasca have also demonstrated serotonergic activity. A case of serotonin syndrome characterized by tremors, sweating, shivering, confusion, nausea, vomiting, and disorientation has been reported in a 36-year-old male who consumed 100 mL of ayahuasca while taking fluoxetine 20 mg daily. Combining serotonergic drugs with ayahuasca might increase the risk of serotonergic side effects including serotonin syndrome and cerebral vasoconstrictive disorders.
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 is a good example of why mixing things with ayahuasca gets tricky. The codeine in it nudges serotonin upward, and the MAOI compounds in ayahuasca (harmine and harmaline) also push serotonin levels higher by slowing the enzyme that normally clears it. Stack those together and you raise the odds of too much serotonin activity at once.
In plain terms, that could mean shivering, sweating, a racing heart, confusion, tremors, nausea, or agitation, which are warning signs of serotonin syndrome. The phenylephrine in this product can add to blood pressure problems alongside an MAOI too. Honestly, this is mostly theoretical and based on how the drugs work, but the risk is serious enough that I would not pair them. Please check with your pharmacist or doctor first.
- Kawanishi, K., Hashimoto, Y., Fujiwara, M., Kataoka, Y., and Ueki, S. Pharmacological characteristics of abnormal behavior induced by harmine with special reference to tremor in mice. J Pharmacobiodyn 1981;4(7):520-527. PubMed
- Herraiz, T., Gonzalez, D., Ancin-Azpilicueta, C., Aran, V. J., and Guillen, H. beta-Carboline alkaloids in Peganum harmala and inhibition of human monoamine oxidase (MAO). Food Chem Toxicol 2010;48(3):839-845. PubMed
- Fuller, R. W., Wong, C. J., and Hemrick-Luecke, S. K. MD 240928 and harmaline: opposite selectivity in antagonism of the inactivation of types A and B monoamine oxidase by pargyline in mice. Life Sci 1986;38(5):409-412. PubMed
- Abdel-Fattah, A. F., Matsumoto, K., Murakami, Y., Adel-Khalek, Gammaz H., Mohamed, M. F., and Watanabe, H. Central serotonin level-dependent changes in body temperature following administration of tryptophan to pargyline- and harmaline-pretreated rats. Ge PubMed
- Bergstrom, M., Westerberg, G., and Langstrom, B. 11C-harmine as a tracer for monoamine oxidase A (MAO-A): in vitro and in vivo studies. Nucl Med Biol 1997;24(4):287-293. PubMed
- Gerardy, J. Effect of moclobemide on rat brain monoamine oxidase A and B: comparison with harmaline and clorgyline. Prog Neuropsychopharmacol Biol Psychiatry 1994;18(4):793-802.
- Sacher, J., Houle, S., Parkes, J., Rusjan, P., Sagrati, S., Wilson, A. A., and Meyer, J. H. Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John's wort: an [11C]-harmine PET study. J Psychiatry
- dos Santos RG. Safety and side effects of ayahuasca in humans--an overview focusing on developmental toxicology. J Psychoactive Drugs. 2013 Jan-Mar;45(1):68-78. PubMed
- dos Santos RG. A critical evaluation of reports associating ayahuasca with life-threatening adverse reactions. J Psychoactive Drugs. 2013 Apr-Jun;45(2):179-88. PubMed
- Callaway JC, Grob CS. Ayahuasca preparations and serotonin reuptake inhibitors: a potential combination for severe adverse interactions. J Psychoactive Drugs. 1998 Oct-Dec;30(4):367-9. PubMed
CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES
2 of 3Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.
Ayahuasca contains beta-carboline alkaloids, including harmine and harmaline. In vitro research suggests that the beta-carboline alkaloids might inhibit CYP2D6 enzymes. This effect has not been reported in humans.
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..
This Colrex combo includes codeine, which is a prodrug. Your body needs the CYP2D6 enzyme to turn codeine into morphine, which is what actually relieves pain and quiets a cough. Lab studies hint that the beta-carboline compounds in ayahuasca (harmine and harmaline) may block CYP2D6. If that happened, your codeine might not convert as well, so you could get less pain and cough relief than expected.
Honestly, this is theoretical and only seen in test-tube research, not in people, so I wouldn't lose sleep over it. The bigger worry is that ayahuasca acts as an MAOI, which can dangerously interact with many cold and allergy ingredients. Please check with your pharmacist or doctor before mixing these.
- Zhao, T., He, Y. Q., Wang, J., Ding, K. M., Wang, C. H., and Wang, Z. T. Inhibition of human cytochrome P450 enzymes 3A4 and 2D6 by β-carboline alkaloids, harmine derivatives. Phytother Res 2011;25(11):1671-1677.
- dos Santos RG. Safety and side effects of ayahuasca in humans--an overview focusing on developmental toxicology. J Psychoactive Drugs. 2013 Jan-Mar;45(1):68-78. PubMed
CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES
3 of 3Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.
Ayahuasca contains beta-carboline alkaloids. In vitro research suggests that beta-carboline alkaloids competitively inhibit CYP3A4 enzymes. 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 is a busy combo product, and the lab-based concern here is that ayahuasca's beta-carboline compounds may gently block CYP3A4, an enzyme your liver uses to clear several of these ingredients. If that clearance slows, levels could creep up, meaning more sedation and grogginess from the chlorpheniramine, plus a higher chance of drowsiness from the codeine. With acetaminophen on board, anything affecting liver enzymes is worth respecting too.
A bigger worry, honestly, is that ayahuasca acts as a strong MAOI, and mixing that with codeine, an opioid, can be genuinely dangerous. The CYP3A4 piece itself is theoretical and only seen in test tubes, not people. Please don't combine these without talking to your doctor or pharmacist first.
- Zhao, T., He, Y. Q., Wang, J., Ding, K. M., Wang, C. H., and Wang, Z. T. Inhibition of human cytochrome P450 enzymes 3A4 and 2D6 by β-carboline alkaloids, harmine derivatives. Phytother Res 2011;25(11):1671-1677.
- dos Santos RG. Safety and side effects of ayahuasca in humans--an overview focusing on developmental toxicology. J Psychoactive Drugs. 2013 Jan-Mar;45(1):68-78. 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.
Ayahuasca Also Interacts With Other Medications
Ayahuasca has 803 moderate known drug interactions in our database — the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine one above is among them. If you take anything else, check it against the full list below.
Check Another of Your Medications Against Ayahuasca
We haven’t checked that one against Ayahuasca yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against Ayahuasca. Pick one to open its full report.
See Every Supplement That Interacts With Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine
This page covers Ayahuasca only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine page lists 338 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), Asarabacca (major), Beer (major) and Ephedra (major).
By severity: 18 major · 275 moderate · 45 minor.
From our pharmacist’s overview on the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine page
“Someone taking Colrex is usually fighting a miserable cold, and cold season is also when people reach for herbal sleep aids and energy boosters, which is exactly where this list bites hardest. Colrex combines acetaminophen, chlorpheniramine, codeine, and phenylephrine, and 18 of its 338 supplement interactions rate major, enough to war…”
Reviewed by 2 · Jul 18, 2026
Open the Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine interaction page
Where Ayahuasca and Acetaminophen, Chlorpheniramine, Codeine, 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.
#743 of 1,452 supplements looked up here in the last 7 days
#517 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 Ayahuasca
What is Ayahuasca?
- Spiritual and ceremonial rituals
- Depression
- Anxiety
- Substance use disorders
- Personal or emotional insight
Ayahuasca is a powerful psychoactive brew that combines a DMT-containing plant with a vine that allows the DMT to take effect, causing intense hallucinations. It is illegal in many places, can trigger dangerous reactions, and is not recommended for self-use; talk to a doctor or pharmacist before considering it.
Other Drugs & Ayahuasca
Browse every other medication we’ve checked against Ayahuasca — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
803 interactions
- Diltiazem ›
- Nifedipine ›
- Hydrocortisone ›
- Methylphenidate ›
- Erythromycin ›
- Estradiol ›
- Propranolol ›
- Lidocaine ›
- Norethindrone ›
- Testosterone ›
- Verapamil ›
- Levonorgestrel ›
- Prednisone ›
- Quinidine ›
- Cyclosporine ›
- Dexamethasone ›
- Triazolam ›
- Zopiclone ›
- Colchicine ›
- Fentanyl ›
- Oxybutynin ›
- Oxycodone ›
- Prednisolone ›
- Tacrolimus ›
- Temazepam ›
- Apomorphine ›
- Budesonide ›
- Carbamazepine ›
- Clindamycin ›
- Dextromethorphan ›
- Doxorubicin ›
- Fluticasone ›
- Formoterol ›
- Miconazole ›
- Morphine Sulfate ›
- Phenylephrine ›
- Trimipramine ›
- Amphetamine ›
- Buprenorphine ›
- Conjugated Estrogens ›
- Diazepam ›
- Everolimus ›
- Ivabradine ›
- Lofepramine ›
- Medroxyprogesterone ›
- Medroxyprogesterone Acetate ›
- Nortriptyline ›
- Propoxyphene ›
- Rifampin ›
- Selegiline ›
- Sumatriptan Succinate ›
- Testosterone Undecanoate ›
- Aripiprazole ›
- Caffeine (otc Drug) ›
- Ciclesonide ›
- Clonazepam ›
- Cyclobenzaprine ›
- Dapsone ›
- Desipramine ›
- Doxepin ›
Showing 60 of 803 moderate interactions — see all 803 on the Ayahuasca page.
No interaction 2,026 drugs checked — show the list
We also checked Ayahuasca against these medications and found no known interaction in our sources. Open any page to confirm.
- Levothyroxine ›
- Ivermectin ›
- Aspirin ›
- Rosuvastatin ›
- Acetaminophen ›
- Docusate ›
- Hydroxyurea ›
- Valacyclovir ›
- Ibuprofen ›
- Tirzepatide ›
- Semaglutide ›
- Metformin ›
- Lisinopril ›
- Amoxicillin ›
- Bupropion ›
- Bendamustine ›
- Acyclovir ›
- Methotrexate ›
- Doxycycline ›
- Lamotrigine ›
- Pregabalin ›
- Azithromycin ›
- Gabapentin ›
- Isotretinoin ›
- Naproxen ›
- Ciprofloxacin ›
- Levothyroxine, Liothyronine ›
- Candesartan Cilexetil ›
- Cephalexin ›
- Cyclopentolate ›
- Acetaminophen, Dextromethorphan, Doxylamine ›
- Roxithromycin ›
- Mannitol ›
- Levetiracetam ›
- Pegunigalsidase Alfa-iwxj ›
- Ezetimibe ›
- Daptomycin ›
- Levothyroxine Sodium ›
- Mitomycin ›
- Valsartan ›
- Spironolactone ›
- Amoxicillin, Clavulanate Potassium ›
- Hexobarbitone ›
- Phentermine, Topiramate ›
- Thyroid Hormone ›
- Acetaminophen, Ibuprofen ›
- Factor 7a ›
- Acetaminophen, Aspirin ›
- Hethylphenidate Hcl ›
- Minoxidil ›
- Lenvatinib ›
- Cefaclor ›
- Azelaic Acid ›
- Ibuprofen, Acetaminophen ›
- Hydroxychloroquine ›
- Tenecteplase ›
- Dirithromycin ›
- Vancomycin ›
- Pizotifen ›
- Triptorelin ›
Showing the 60 most looked-up of 2,026 medications checked with no known interaction — see the full Ayahuasca 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, Chlorpheniramine, Codeine, Phenylephrine Is Linked to Lower Levels of One Nutrient
Natural Medicines records Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine as a medicine that can lower these. This is not an interaction with Ayahuasca — it is a separate effect of the medicine, and it is a reason some people are advised to supplement rather than to avoid one:
Read the full Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine nutrient depletion report ›
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 Ayahuasca and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine Together: Common Questions
Can you take Ayahuasca with Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine?
Why are there 3 interactions listed for Ayahuasca and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine?
How serious is the Ayahuasca and Acetaminophen, Chlorpheniramine, Codeine, Phenylephrine interaction?
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.