Drug & supplement interaction

Sweet Vernal Grass + acetaminophen, dextromethorphan, doxylamine

acetaminophen, dextromethorphan, doxylamine brand name: NyQuil.

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 Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine 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

Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine

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 acetaminophen, dextromethorphan, doxylamine and Sweet Vernal Grass 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.

Sweet Vernal Grass safety at a glance

Sweet Vernal Grass overall Use caution Generally used in small amounts as a flavoring, but human safety data as a supplement is very limited and it can trigger allergies.
Pregnancy Possibly Safe When used sublingually as prescribed. An FDA-approved prescription combination product (Oralair) containing sweet vernal grass, orchard grass, perennial rye gra... Read the full pregnancy detail
Breastfeeding Possibly Safe When used sublingually as prescribed. An FDA-approved prescription combination product (Oralair) containing sweet vernal grass, orchard grass, perennial rye gra... Read the full breastfeeding detail

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 acetaminophen, dextromethorphan, doxylamine and Sweet Vernal Grass? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for acetaminophen, dextromethorphan, doxylamine

Interactions in our licensed database are recorded against drug classes, not just single drug names. acetaminophen, dextromethorphan, doxylamine is filed under 4 classifications — including cns depressants, oral drugs. Sweet Vernal Grass has documented interactions with 1 drug class — the most serious being anticoagulant/antiplatelet drugs (moderate) — and none of acetaminophen, dextromethorphan, doxylamine’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

Sweet Vernal Grass Does Interact With Other Medications

Sweet Vernal Grass has 122 moderate known drug interactions in our database — acetaminophen, dextromethorphan, doxylamine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 122 No known interaction 2,708 (incl. acetaminophen, dextromethorphan, doxylamine)
Taking anything else?

Check Another of Your Medications Against Sweet Vernal Grass

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

What to actually watch for

What Sweet Vernal Grass Itself Has Been Linked To

This is not an interaction — nothing below involves acetaminophen, dextromethorphan, doxylamine. It is the side-effect record for Sweet Vernal Grass on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Sweet Vernal Grass, this list is the first place to look. 2 entries are worth acting on rather than waiting out — marked below.

  • A severe allergic reaction / Hives Worth acting on Additional detail

    “Sublingually, an FDA-approved combination product (Oralair) containing sweet vernal grass, orchard grass, perennial rye grass, Timothy grass, and Kentucky blue grass pollen extracts can cause pruritus, oral edema, throat irritation, and urticaria. It can also cause severe, life threatening allergic reactions including laryngopharyngeal swelling, angioedema, and anaphylaxis in highly sensitized individuals.”

    Sweet Vernal Grass · Natural Medicines adverse-effect record, reported in pruritus.

    2 sources cited
    1. 97264. Didier A, Bons B. Safety and tolerability of 5-grass pollen tablet sublingual immunotherapy: pooled analysis and clinical review. Expert Opin Drug Saf 2015;14(5):777-88. doi: 10.1517/14740338.2015.1017468. PubMed
    2. 97265. Oralair Product Information. (Sweet vernal, orchard, perennial rye, timothy, and Kentucky blue grass mixed pollens allergen extract). Stallergenes S.A., France. 2014. https://www.fda.gov/downloads/BiologicsBloodVaccines/Allergenics/UCM391580.pdf (accessed
  • An allergic reaction Worth acting on Additional detail

    “Sublingually, an FDA-approved prescription combination product (Oralair) of sweet vernal grass, orchard grass, perennial rye grass, Timothy grass, and Kentucky blue grass pollen allergen extracts can cause mouth edema and pruritus, throat edema, dyspepsia, and cough. There are also rare reports of severe hypersensitivity reactions.”

    Sweet Vernal Grass · Natural Medicines adverse-effect record, reported in cough.

    2 sources cited
    1. 97264. Didier A, Bons B. Safety and tolerability of 5-grass pollen tablet sublingual immunotherapy: pooled analysis and clinical review. Expert Opin Drug Saf 2015;14(5):777-88. doi: 10.1517/14740338.2015.1017468. PubMed
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  • Sore throat Additional detail

    Recorded for Sweet Vernal Grass in the same Natural Medicines adverse-effect record shown under A severe allergic reaction / Hives above.

  • Cough / Stomach upset Additional detail

    Recorded for Sweet Vernal Grass in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

  • Itching / Swelling Additional detail

    Recorded for Sweet Vernal Grass in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

  • Dizziness / Headache Additional detail

    “Orally, use of large doses of sweet vernal grass can cause headaches and dizziness (18).”

    Sweet Vernal Grass · Natural Medicines adverse-effect record, reported in vertigo.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

Everything above comes from the Natural Medicines adverse-effect record for Sweet Vernal Grass — expand a row for the licensed statement it rests on. We haven’t matched acetaminophen, dextromethorphan, doxylamine 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 acetaminophen, dextromethorphan, doxylamine.

Special populations

Sweet Vernal Grass in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Safe

When used sublingually as prescribed. An FDA-approved prescription combination product (Oralair) containing sweet vernal grass, orchard grass, perennial rye grass, Timothy grass, and Kentucky blue grass pollen extracts has been used sublingually with apparent safety during pregnancy.

Pregnancy And Lactation Likely Unsafe

When dried sweet vernal grass is used orally; avoid using.

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 acetaminophen, dextromethorphan, doxylamine

This page covers Sweet Vernal Grass only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the acetaminophen, dextromethorphan, doxylamine page lists 106 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), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 8 major · 78 moderate · 20 minor.

From our pharmacist’s overview on the acetaminophen, dextromethorphan, doxylamine page

“NyQuil (acetaminophen, dextromethorphan, doxylamine) is designed to make you drowsy, and that is exactly where most of its supplement interactions live. Seventy-eight of the 106 ingredients on this list add to its sedation, and the eight rated major, alcohol and kava among them, can push a nighttime cold remedy toward serious depressio…”

Reviewed by 2 · Jul 18, 2026

Open the acetaminophen, dextromethorphan, doxylamine interaction page

How much people look this up

Where Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine 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 Sweet Vernal Grass
Steady interest

#1,445 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication acetaminophen, dextromethorphan, doxylamine
Top 5%

#79 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 Sweet Vernal Grass reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine records this page draws on were last updated July 10, 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 Sweet Vernal Grass

What is Sweet Vernal Grass?

  • Trouble sleeping
  • Mild anxiety or restlessness
  • Hay fever and allergy symptoms (as a known trigger, sometimes studied)
  • Used as a fragrant flavoring in foods and drinks
  • Folk use for nausea or upset stomach

Sweet Vernal Grass is a fragrant European meadow grass best known for the sweet, hay-like smell it gets from coumarin. It has a long history as a flavoring and a folk calming remedy, but there is very little human research to support any health benefit. It is also a well-known cause of grass-pollen allergies, so people prone to hay fever should be cautious.

Anthoxanthum odoratum · Poaceae · Leaves, flowering tops, and dried grass (whole herb) · Dried herb, tea/infusion, tincture, and as a flavoring/scent component (coumarin source)

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

Sweet Vernal Grass: dosing

There is no established or standardized dose for Sweet Vernal Grass as a supplement. Reliable dosing information from clinical studies does not exist.If you choose to use a product that contains it, follow the directions on the product label and do not exceed the recommended amount.

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

Read the full Sweet Vernal Grass monograph & all interactions
Keep checking

Other Drugs & Sweet Vernal Grass

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

0Major
122Moderate
0Minor
2,707No known interaction
122 Moderate 2,707 No interaction
Moderate

122 interactions

Showing 60 of 122 moderate interactions — see all 122 on the Sweet Vernal Grass page.

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Sweet Vernal Grass list.

See the full Sweet Vernal Grass interactions page
See every supplement checked against acetaminophen, dextromethorphan, doxylamine, ranked by severity
Evidence & sources

Sweet Vernal Grass References

The 5 references that drive our Sweet Vernal Grass 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  3. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  4. Didier A, Bons B. Safety and tolerability of 5-grass pollen tablet sublingual immunotherapy: pooled analysis and clinical review. Expert Opin Drug Saf 2015;14(5):777-88. doi: 10.1517/14740338.2015.1017468. PubMed
  5. Oralair Product Information. (Sweet vernal, orchard, perennial rye, timothy, and Kentucky blue grass mixed pollens allergen extract). Stallergenes S.A., France. 2014. https://www.fda.gov/downloads/BiologicsBloodVaccines/Allergenics/UCM391580.pdf (accessed

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 Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine Together: Common Questions

Is it safe to take Sweet Vernal Grass with acetaminophen, dextromethorphan, doxylamine?
We do not list a known interaction between Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine. 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 Sweet Vernal Grass and acetaminophen, dextromethorphan, doxylamine combination checked?
Interactions in our licensed database are recorded against drug classes. acetaminophen, dextromethorphan, doxylamine is filed under 4 classifications, and Sweet Vernal Grass has documented interactions with 1 drug class — none of acetaminophen, dextromethorphan, doxylamine'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 Sweet Vernal Grass interact with any other medications?
Yes. Sweet Vernal Grass has 122 documented drug interactions in our database — acetaminophen, dextromethorphan, doxylamine 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 acetaminophen, dextromethorphan, doxylamine interact with any supplements?
Yes. acetaminophen, dextromethorphan, doxylamine has documented interactions with 106 supplements in our database — Sweet Vernal Grass is not one of them. The acetaminophen, dextromethorphan, doxylamine 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

Sweet Vernal Grass monograph Uses, safety profile, and every drug interaction in one place acetaminophen, dextromethorphan, doxylamine supplement interactions Every supplement checked against acetaminophen, dextromethorphan, doxylamine, 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 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About acetaminophen, dextromethorphan, doxylamine and Sweet Vernal Grass?

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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.