Drug & supplement interaction

Parsley + Dextromethorphan HBr, Guaifenesin

Dextromethorphan HBr, Guaifenesin brand names: Vicks Formula 44E Cough & Chest Congestion Relief, Pediatric Vicks Formula 44e Cough & Chest Congesti.

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 Parsley and Dextromethorphan HBr, Guaifenesin 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.

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Interaction report

Parsley and Dextromethorphan HBr, Guaifenesin

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 Dextromethorphan HBr, Guaifenesin and Parsley 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.

Parsley safety at a glance

Parsley overall Use caution Safe as a food, but concentrated extracts, seeds, and essential oil may not be safe in large amounts.
Pregnancy Likely Unsafe When used orally in medicinal amounts. Parsley has been used orally as an abortifacient and to stimulate menstrual flow. Population evidence suggests that mater... Read the full pregnancy detail
Breastfeeding Use caution Food amounts are likely fine, but avoid concentrated supplements due to lack of safety data.

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 Dextromethorphan HBr, Guaifenesin and Parsley? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Dextromethorphan HBr, Guaifenesin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Dextromethorphan HBr, Guaifenesin is filed under 6 classifications — including serotonergic drugs, serotonergic drugs, cytochrome p450 2d6 (cyp2d6) substrates. Parsley has documented interactions with 8 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), antidiabetes drugs (moderate) and cytochrome p450 1a2 (cyp1a2) substrates (moderate) — and none of Dextromethorphan HBr, Guaifenesin’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

Parsley Does Interact With Other Medications

Parsley has 443 moderate known drug interactions in our database — Dextromethorphan HBr, Guaifenesin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 443 No known interaction 2,387 (incl. Dextromethorphan HBr, Guaifenesin)
Taking anything else?

Check Another of Your Medications Against Parsley

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

What to actually watch for

What Parsley Itself Has Been Linked To

This is not an interaction — nothing below involves Dextromethorphan HBr, Guaifenesin. It is the side-effect record for Parsley on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Parsley, this list is the first place to look. 4 entries are worth acting on rather than waiting out — marked below.

  • A slow heartbeat Worth acting on Additional detail

    “Parsley contains the potentially toxic constituent, myristicin, which can cause significant adverse effects at high doses (11). Adverse effects specifically associated with myristicin include hypotension and bradycardia (4).”

    Parsley · Natural Medicines adverse-effect record, reported in hypotension.

    2 sources cited
    1. 11. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
    2. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  • Hallucinations Worth acting on Additional detail

    “Orally, parsley seems to be well tolerated when used low to moderate doses. Large doses may be unsafe.

    Serious Adverse Effects (Rare):

    Orally, Hallucinations, hemolytic anemia, hypotension, hepatic impairment, kidney impairment, nephrotic syndrome, paralysis, and thrombocytopenia purpura when taken in very high doses (200 grams parsley oil or 10 grams or more of parsley's apiole or myristicin constituents).”

    Parsley · Natural Medicines adverse-effect record, reported in anemia.

  • A low platelet count / Anemia / Bleeding or bruising Worth acting on Additional detail

    “Parsley contains the potentially toxic constituent apiole, which can cause significant adverse effects at high doses (11). Adverse effects specifically associated with more than 10 grams of the constituent apiole include hemolytic anemia and thrombocytopenia purpura (4).”

    Parsley · Natural Medicines adverse-effect record, reported in anemia.

    2 sources cited
    1. 11. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
    2. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  • A severe allergic reaction Worth acting on Additional detail

    “A case of anaphylaxis involving severe angioedema leading to unconsciousness has been reported in a woman who consumed parsley 45 minutes prior to symptoms. The patient responded to epinephrine, antihistamines, intravenous fluids, oxygen therapy, and 1 mg/kg methylprednisolone.”

    Parsley · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    2 sources cited
    1. 92869. Arslan S, Ucar R, Caliskaner AZ. A Cases of Near-fatal Anaphylaxis: Parsley "Over-use" as an Herbal Remedy. Med Arch. 2014;68(6):426-7.
    2. 92870. Foti C, Cassano N, Mistrello G, Amato S, Romita P, Vena GA. Contact urticaria to raw arugula and parsley. Ann Allergy Asthma Immunol. 2011 May;106(5):447-8. PubMed
  • Low blood pressure Additional detail

    Recorded for Parsley in the same Natural Medicines adverse-effect record shown under Hallucinations above.

Everything above comes from the Natural Medicines adverse-effect record for Parsley — expand a row for the licensed statement it rests on. We haven’t matched Dextromethorphan HBr, Guaifenesin to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Dextromethorphan HBr, Guaifenesin.

Special populations

Parsley in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally in medicinal amounts. Parsley has been used orally as an abortifacient and to stimulate menstrual flow. Population evidence suggests that maternal intake of An-Tai-Yin, an herbal combination product containing parsley and dong quai, during the first trimester increases the risk of congenital malformations of the musculoskeletal system, connective tissue, and eyes.

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 Dextromethorphan HBr, Guaifenesin

This page covers Parsley only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Dextromethorphan HBr, 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 HBr, Guaifenesin page

“A bad cough tends to hit when supplements are already on the counter, and anyone reaching for Vicks Formula 44E (dextromethorphan HBr and guaifenesin) should treat this list with real care, since 4 of its 171 entries carry a major rating. Two themes dominate.”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan HBr, Guaifenesin interaction page

One more smart check

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

We hold 3,292 real supplement products containing Parsley, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Parsley. Even though Parsley itself has no known interaction with Dextromethorphan HBr, Guaifenesin, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Parsley and Dextromethorphan HBr, 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 Parsley
Top 10%

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

29 days ago today
Medication Dextromethorphan HBr, Guaifenesin
Top half

#838 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 Parsley reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Parsley and Dextromethorphan HBr, Guaifenesin records this page draws on were last updated July 11, 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 Parsley

What is Parsley?

Parsley
  • Water retention and bloating
  • Urinary and bladder support
  • Digestive upset
  • Freshening breath
  • Source of vitamins and antioxidants

Parsley is a popular culinary herb that is safe to eat in normal food amounts and is a good source of vitamins K and C. It is traditionally used as a diuretic and for digestion, but solid human evidence for medicinal benefits is limited. Concentrated supplements, seed extracts, and the essential oil are much stronger than food and should be used cautiously, especially during pregnancy.

Petroselinum crispum · Apiaceae · Leaves, seeds, root, and essential oil · Fresh or dried herb, tea, capsules, extracts, seed oil, essential oil

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

Parsley: dosing

There is no well-established standardized medicinal dose for parsley. Using it as a food or in a cup of parsley tea is the most common and lowest-risk way to take it.If you choose a parsley supplement, follow the directions on the product label and do not exceed the recommended amount. Avoid the concentrated essential oil and high-dose seed products unless guided by a healthcare professional.

From our Parsley monograph — the full record covers uses, side effects and every documented interaction.

Read the full Parsley monograph & all interactions
Medication

About Dextromethorphan HBr, Guaifenesin

Most-Reported Side Effects for Dextromethorphan HBr, Guaifenesin

From FAERS, the FDA’s public side-effect reporting system (1,675 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 140 reports
Pneumonia 123 reports
Nausea 120 reports
Cough 119 reports
Fatigue 118 reports
Keep checking

Other Drugs & Parsley

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

0Major
443Moderate
0Minor
2,386No known interaction
443 Moderate 2,386 No interaction
Moderate

443 interactions

Showing 60 of 443 moderate interactions — see all 443 on the Parsley page.

No interaction 2,386 drugs checked — show the list

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

Showing the 60 most looked-up of 2,386 medications checked with no known interaction — see the full Parsley list.

See the full Parsley interactions page
See every supplement checked against Dextromethorphan HBr, Guaifenesin, ranked by severity
Evidence & sources

Parsley References

The 21 references that drive our Parsley 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. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  5. Robbers JE, Tyler VE. Tyler's Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York, NY: The Haworth Herbal Press, 1999.
  6. Foster S, Tyler VE. Tyler's Honest Herbal, 4th ed., Binghamton, NY: Haworth Herbal Press, 1999. DOI
  7. Eberhard P, Gall HM, Muller I, Moller R. Dramatic augmentation of a food allergy by acetylsalicylic acid. J Allergy Clin Immunol 2000;105:844 PubMed
  8. Tunali T, Yarat A, Yanardag R, et al. Effect of parsley (Petroselinum crispum) on the skin of STZ induced diabetic rats. Phytother Res 1999;13:138-41.. DOI
  9. Chuang CH, Doyle P, Wang JD, et al. Herbal medicines used during the first trimester and major congenital malformations: an analysis of data from a pregnancy cohort study. Drug Saf 2006;29:537-48. PubMed
  10. Ciganda C, and Laborde A. Herbal infusions used for induced abortion. J Toxicol.Clin Toxicol. 2003;41:235-239. PubMed
  11. Jakovljevic, V., Raskovic, A., Popovic, M., and Sabo, J. The effect of celery and parsley juices on pharmacodynamic activity of drugs involving cytochrome P450 in their metabolism. Eur.J Drug Metab Pharmacokinet. 2002;27(3):153-156. PubMed
  12. Kreydiyyeh, S. I. and Usta, J. Diuretic effect and mechanism of action of parsley. J Ethnopharmacol 2002;79(3):353-357. PubMed
  13. Yanardag, R., Bolkent, S., Tabakoglu-Oguz, A., and Ozsoy-Sacan, O. Effects of Petroselinum crispum extract on pancreatic B cells and blood glucose of streptozotocin-induced diabetic rats. Biol Pharm Bull. 2003;26(8):1206-1210. PubMed
  14. Bolkent, S., Yanardag, R., Ozsoy-Sacan, O., and Karabulut-Bulan, O. Effects of parsley (Petroselinum crispum) on the liver of diabetic rats: a morphological and biochemical study. Phytother.Res 2004;18(12):996-999.
  15. Ozsoy-Sacan, O., Yanardag, R., Orak, H., Ozgey, Y., Yarat, A., and Tunali, T. Effects of parsley (Petroselinum crispum) extract versus glibornuride on the liver of streptozotocin-induced diabetic rats. J Ethnopharmacol 3-8-2006;104(1-2):175-181. 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 Parsley and Dextromethorphan HBr, Guaifenesin Together: Common Questions

Is it safe to take Parsley with Dextromethorphan HBr, Guaifenesin?
We do not list a known interaction between Parsley and Dextromethorphan HBr, Guaifenesin. 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.
How was the Parsley and Dextromethorphan HBr, Guaifenesin combination checked?
Interactions in our licensed database are recorded against drug classes. Dextromethorphan HBr, Guaifenesin is filed under 6 classifications, and Parsley has documented interactions with 8 drug classes — none of Dextromethorphan HBr, Guaifenesin'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 Parsley interact with any other medications?
Yes. Parsley has 443 documented drug interactions in our database — Dextromethorphan HBr, Guaifenesin 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 Dextromethorphan HBr, Guaifenesin interact with any supplements?
Yes. Dextromethorphan HBr, Guaifenesin has documented interactions with 171 supplements in our database — Parsley is not one of them. The Dextromethorphan HBr, Guaifenesin 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

Parsley monograph Uses, safety profile, and every drug interaction in one place Dextromethorphan HBr, Guaifenesin supplement interactions Every supplement checked against Dextromethorphan HBr, 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 References The 21 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.