Drug & supplement interaction

Squill + Dextromethorphan

Dextromethorphan brand names: Hold, Benylin Adult, Benylin Pediatric, Theraflu Thin Strips Long Acting Cough, Neo Citran Thin Strips Cough.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Squill and Dextromethorphan 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

Squill and Dextromethorphan

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 and Squill 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.

Squill safety at a glance

Squill overall Use caution Squill contains heart-active glycosides that can be toxic, so it should only be used under medical supervision.
Pregnancy Unsafe When used orally because it can have an abortifacient effect. Read the full pregnancy detail
Breastfeeding Unsafe When used orally. 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 Dextromethorphan and Squill? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Dextromethorphan

Interactions in our licensed database are recorded against drug classes, not just single drug names. Dextromethorphan is filed under 6 classifications — including serotonergic drugs, serotonergic drugs, cytochrome p450 2d6 (cyp2d6) substrates. Squill has documented interactions with 7 drug classes — the most serious being digoxin (lanoxin) (major), corticosteroids (moderate) and diuretic drugs (moderate) — and none of Dextromethorphan’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

Squill Does Interact With Other Medications

Squill has 1 major, 155 moderate known drug interactions in our database — Dextromethorphan isn’t one of them. If you take anything else, check it against the full list below.

Major 1 Moderate 155 No known interaction 2,674 (incl. Dextromethorphan)
Taking anything else?

Check Another of Your Medications Against Squill

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

What to actually watch for

What Squill Itself Has Been Linked To

This is not an interaction — nothing below involves Dextromethorphan. It is the side-effect record for Squill on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Squill, this list is the first place to look. 3 entries are worth acting on rather than waiting out — marked below.

  • Hallucinations / Low mood Worth acting on Additional detail

    “Squill is generally regarded as unsafe for use. Any benefits of therapy might not outweigh the risk of toxicity. Orally, squill can cause gastric irritation, loss of appetite, diarrhea, nausea, vomiting, stomach disorders, headache, irregular pulse (18,94852), and convulsions (6). Squill poisoning resembles digoxin poisoning.”

    Squill · Natural Medicines adverse-effect record, reported in arrhythmia.

    4 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 94852. Nejatbakhsh F, Karegar-Borzi H, Amin G, et al. Squill Oxymel, a traditional formulation from Drimia Maritima (L.) Stearn, as an add-on treatment in patients with moderate to severe persistent asthma: A pilot, triple-blind, randomized clinical trial. J Eth PubMed
    3. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    4. 3488. Tuncok Y, Kozan O, Cavdar C, et al. Urginea maritima (squill) toxicity. J Toxicol Clin Toxicol 1995;33:83-6.

    “Squill poisoning resembles digoxin poisoning. The psychiatric symptoms of squill poisoning include depression, confusion, hallucinations, and psychosis (18,3488).”

    Squill · Natural Medicines adverse-effect record, reported in depression.

    2 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 3488. Tuncok Y, Kozan O, Cavdar C, et al. Urginea maritima (squill) toxicity. J Toxicol Clin Toxicol 1995;33:83-6.
  • An irregular heartbeat Worth acting on Additional detail

    “Orally, squill can cause irregular pulse (18,94852).

    Squill poisoning resembles digoxin poisoning. The cardiovascular symptoms of squill poisoning include cardiac arrest and life-threatening arrhythmias, including ventricular tachycardia, atrial tachycardia with atrioventricular block, and ventricular fibrillation (18,3488).”

    Squill · Natural Medicines adverse-effect record, reported in arrhythmia.

    3 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 94852. Nejatbakhsh F, Karegar-Borzi H, Amin G, et al. Squill Oxymel, a traditional formulation from Drimia Maritima (L.) Stearn, as an add-on treatment in patients with moderate to severe persistent asthma: A pilot, triple-blind, randomized clinical trial. J Eth PubMed
    3. 3488. Tuncok Y, Kozan O, Cavdar C, et al. Urginea maritima (squill) toxicity. J Toxicol Clin Toxicol 1995;33:83-6.
  • Confusion / Seizures Worth acting on Additional detail

    “Orally, squill can cause headache and convulsions (6).

    Squill poisoning resembles digoxin poisoning. The neurologic symptoms of squill poisoning include confusion, restlessness, stupor, and seizure (18,3488).”

    Squill · Natural Medicines adverse-effect record, reported in cluster headache.

    3 sources cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    2. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    3. 3488. Tuncok Y, Kozan O, Cavdar C, et al. Urginea maritima (squill) toxicity. J Toxicol Clin Toxicol 1995;33:83-6.
  • A fast or pounding heartbeat Additional detail

    Recorded for Squill in the same Natural Medicines adverse-effect record shown under An irregular heartbeat above.

  • Anxiety or restlessness Additional detail

    Recorded for Squill in the same Natural Medicines adverse-effect record shown under Hallucinations / Low mood above.

  • Reduced appetite / Stomach upset / Diarrhea Additional detail

    “Orally, squill can cause gastric irritation, loss of appetite, diarrhea, nausea, vomiting, and stomach disorders (18,94852).”

    Squill · Natural Medicines adverse-effect record, reported in diarrhea.

    2 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 94852. Nejatbakhsh F, Karegar-Borzi H, Amin G, et al. Squill Oxymel, a traditional formulation from Drimia Maritima (L.) Stearn, as an add-on treatment in patients with moderate to severe persistent asthma: A pilot, triple-blind, randomized clinical trial. J Eth PubMed

Showing the 10 most notable of 14 recorded effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

Everything above comes from the Natural Medicines adverse-effect record for Squill — expand a row for the licensed statement it rests on. We haven’t matched Dextromethorphan 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.

Special populations

Squill in Pregnancy & Breastfeeding

Pregnancy Unsafe

When used orally because it can have an abortifacient effect.

Lactation Unsafe

When used orally.

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

From our Q&A

Questions About Squill or Dextromethorphan

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Squill or Dextromethorphan, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Dextromethorphan

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

“A glass of grapefruit juice can push dextromethorphan (Benylin, Hold, and other cough medicines) to higher levels than intended, one of four major-rated entries among the 171 supplements and herbs on file, and the list as a whole warrants real care. Most interactions trace back to the liver enzymes (CYP3A4 and CYP2D6) that clear dextro…”

Reviewed by 2 · Jul 18, 2026

Open the Dextromethorphan interaction page

One more smart check

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

We hold 2 real supplement products containing Squill, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Squill. Even though Squill itself has no known interaction with Dextromethorphan, 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 Squill and Dextromethorphan 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 Squill
Top half

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

29 days ago today
Medication Dextromethorphan
Top 25%

#616 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 Squill reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Squill and Dextromethorphan 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 Squill

What is Squill?

Squill
  • Cough and chest congestion
  • Fluid retention (diuretic)
  • Heart conditions (traditional 'cardiac tonic')
  • Hair loss (topical use)
  • Rodenticide (red squill, non-medicinal)

Squill is a bulb plant that contains potent cardiac glycosides, which can affect the heart much like the drug digoxin. While it has a long history of use as a cough remedy and heart tonic, it can be dangerously toxic and there is little solid evidence for its modern use, so we do not recommend taking it without close medical supervision.

Drimia maritima · Asparagaceae · Dried inner bulb scales · Dried bulb, tinctures, liquid extracts, syrups, and some traditional cough preparations

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

Squill: dosing

There is no well-established, standardized safe dose of squill for general use. Because the active compounds are so potent and the toxic dose is close to any possibly effective dose, self-dosing is not recommended.If a product contains squill, follow the label exactly and do not take more than directed.

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

Read the full Squill monograph & all interactions
Medication

About Dextromethorphan

What Is Dextromethorphan Used For?

Brand names: Hold, Benylin Adult, Benylin Pediatric, Theraflu Thin Strips Long Acting Cough, Neo Citran Thin Strips Cough

Dextromethorphan temporarily relieves cough due to minor throat and bronchial irritation, such as the kind that comes with the common cold or breathing in irritants. It also helps reduce the urge to cough so you — or your child — can get to sleep.

Some products, including CVS Long Acting Cough and Premier Value Tussin Cough oral liquids, are also indicated to help loosen phlegm (mucus) and thin bronchial secretions to help drain the airways.

See full Dextromethorphan drug information
Keep checking

Other Drugs & Squill

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

1Major
155Moderate
0Minor
2,673No known interaction
1 Major 155 Moderate 2,673 No interaction
Major

1 interaction

Moderate

155 interactions

Showing 60 of 155 moderate interactions — see all 155 on the Squill page.

No interaction 2,673 drugs checked — show the list

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

Showing the 60 most looked-up of 2,673 medications checked with no known interaction — see the full Squill list.

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

Squill References

The 9 references that drive our Squill 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. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  3. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  4. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
  5. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  6. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  7. Tuncok Y, Kozan O, Cavdar C, et al. Urginea maritima (squill) toxicity. J Toxicol Clin Toxicol 1995;33:83-6.
  8. Nejatbakhsh F, Karegar-Borzi H, Amin G, et al. Squill Oxymel, a traditional formulation from Drimia Maritima (L.) Stearn, as an add-on treatment in patients with moderate to severe persistent asthma: A pilot, triple-blind, randomized clinical trial. J Eth PubMed
  9. Moosavi ZB, Aliabdi M, Golfakhrabadi F, Namjoyan F. The comparison of therapeutic effect of Clobetasol propionate lotion and squill extract in alopecia areata: a randomized, double-blind clinical trial. Arch Dermatol Res. 2020 Apr;312(3):173-178. 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 Squill and Dextromethorphan Together: Common Questions

Is it safe to take Squill with Dextromethorphan?
We do not list a known interaction between Squill and Dextromethorphan. 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 Squill and Dextromethorphan combination checked?
Interactions in our licensed database are recorded against drug classes. Dextromethorphan is filed under 6 classifications, and Squill has documented interactions with 7 drug classes — none of Dextromethorphan'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 Squill interact with any other medications?
Yes. Squill has 156 documented drug interactions in our database — Dextromethorphan 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 interact with any supplements?
Yes. Dextromethorphan has documented interactions with 171 supplements in our database — Squill is not one of them. The Dextromethorphan 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

Squill monograph Uses, safety profile, and every drug interaction in one place Dextromethorphan drug information The full plain-English guide to this medication Dextromethorphan supplement interactions Every supplement checked against Dextromethorphan, 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 9 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Dextromethorphan and Squill?

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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.