Drug & supplement interaction

Watercress + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Oct 4, 2026

The bottom line No known interaction

We found no known interaction between Watercress and Phenylephrine 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Watercress and Phenylephrine

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 Phenylephrine and Watercress 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.

Watercress safety at a glance

Watercress overall Generally safe Generally safe as a food for most adults in normal culinary amounts.

Pregnancy Likely Unsafe When used in medicinal amounts. Watercress might stimulate menstruation or have abortifacient effects. Read the full pregnancy detail

Breastfeeding Use caution Food amounts are likely fine; avoid medicinal or concentrated doses due to lack of 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 Phenylephrine and Watercress? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Phenylephrine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phenylephrine is filed under 5 classifications — including alpha-adrenergic agonists, stimulant drugs, serotonergic drugs. Watercress has documented interactions with 3 drug classes — the most serious being chlorzoxazone (parafon forte, paraflex) (moderate), lithium (moderate) and warfarin (coumadin) (moderate) — and none of Phenylephrine’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

Watercress Does Interact With Other Medications

Watercress has 6 moderate known drug interactions in our database — Phenylephrine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 6 No known interaction 2,824 (incl. Phenylephrine)

Taking anything else?

Check Another of Your Medications Against Watercress

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

What to actually watch for

No Interaction Found — But Data Suggests Watercress and Phenylephrine May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

Vomiting Additional detail
Watercress
“Raw, wild watercress can be contaminated with parasitic flukes which, when ingested, cause the liver disease fascioliasis. Symptoms include abdominal pain, fever, vomiting, diarrhea, urticaria, eosinophilia, and hepatomegaly. Clinical research shows that taking a standardized extract of watercress orally 750 mg/kg daily for 5 weeks is not associated with increases in liver function enzymes.”

Watercress · Natural Medicines adverse-effect record, reported in cirrhosis.
6 sources cited

85575. Dobrucali, A., Yigitbasi, R., Erzin, Y., Sunamak, O., Polat, E., and Yakar, H. Fasciola hepatica infestation as a very rare cause of extrahepatic cholestasis. World J Gastroenterol. 10-15-2004;10(20):3076-3077. PubMed

85574. Yilmaz, H. and Godekmerdan, A. Human fasciolosis in Van province, Turkey. Acta Trop. 2004;92(2):161-162.

85573. Carrada-Bravo, T. [Fascioliasis: diagnosis, epidemiology and treatment]. Rev Gastroenterol.Mex. 2003;68(2):135-142.

85567. Cosme, A., Ojeda, E., Poch, M., Bujanda, L., Castiella, A., and Fernandez, J. Sonographic findings of hepatic lesions in human fascioliasis. J Clin Ultrasound 2003;31(7):358-363. PubMed

85564. Christmann, M., Henrich, R., Mayer, G., and Ell, C. [Infection with fasciola hepatica causing elevated liver-enzyme results and eosinophilia - serologic and endoscopic diagnosis and therapy]. Z.Gastroenterol. 2002;40(9):801-806.

85582. Cruz, Lopez O., Adan, Pimentel A., Tamariz Cruz, O. J., Munoz, Lopez A., Cruz Lopez, M. C., Cruz Lopez, M. E., and Munoz, Lopez S. [Hepatic fasciolasis diagnosed in state phase]. Rev Gastroenterol Mex. 2006;71(1):59-62.
Phenylephrine

Listed in the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed ›

Reported for Watercress but not commonly for Phenylephrine: stomach pain, kidney problems, a skin rash and hives.

Effects for Phenylephrine come from the ADVERSE REACTIONS section of its FDA label; effects for Watercress come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 221,388 voluntary FDA FAERS reports for Phenylephrine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Watercress in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used in medicinal amounts. Watercress might stimulate menstruation or have abortifacient effects.

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 Watercress or Phenylephrine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Watercress or Phenylephrine, 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 Phenylephrine

This page covers Watercress only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine interaction page

One more smart check

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

We hold 820 real supplement products containing Watercress, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Watercress. Even though Watercress itself has no known interaction with Phenylephrine, 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 Watercress and 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.

Supplement Watercress

Top 25%

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

29 days ago today

Medication Phenylephrine

Top half

#714 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 Watercress reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Watercress and Phenylephrine 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Watercress

What is Watercress?

Source of vitamins and minerals
Antioxidant support
General nutrition
Traditional cough and congestion remedy
Skin and detox tonics

Watercress is a nutrient-rich leafy green that provides vitamins A, C, and K plus minerals and antioxidant plant compounds. Eaten as a food it is generally safe and healthy for most people, but strong human evidence for concentrated supplement health claims is limited. Talk to your pharmacist or doctor before using high-dose extracts, especially if you are pregnant, breastfeeding, or have a medical condition.

Nasturtium officinale · Brassicaceae · Leaves and stems (above-ground parts) · Fresh leafy green, salad, juice, extract capsules, dried herb

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

Watercress: dosing

There is no official or standardized dose for watercress as a supplement. As a food, it is simply eaten in salads or cooked dishes in the amount you enjoy.For capsules, powders, or extracts, follow the directions on the product label, since strength varies between products. More is not always better, and concentrated extracts have not been well studied for safety.

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

Read the full Watercress monograph & all interactions

Medication

About Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in several different products, and each one has its own use.

Injection (IV): raises blood pressure in adults with clinically important hypotension (low blood pressure) caused mainly by widened blood vessels. Some injections are labeled for anesthesia only. Others are labeled for anesthesia and septic shock.

Eye drops: Phenylephrine Hydrochloride Ophthalmic Solution is used to dilate the pupil.

Nasal products: temporarily relieve nasal and sinus congestion from the common cold, hay fever or other upper respiratory allergies.

Rectal suppositories: relieve itching, burning and discomfort from hemorrhoids and temporarily shrink hemorrhoidal tissue.

Most-Reported Side Effects for Phenylephrine

From FAERS, the FDA’s public side-effect reporting system (221,388 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 20,609 reports

Headache 17,301 reports

Nausea 16,925 reports

Diarrhea 14,221 reports

Dyspnea 13,719 reports

See full Phenylephrine drug information

Keep checking

Other Drugs & Watercress

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

0Major

6Moderate

0Minor

2,823No known interaction

6 Moderate 2,823 No interaction

Moderate

6 interactions

No interaction 2,823 drugs checked — show the list

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

Showing the 60 most looked-up of 2,823 medications checked with no known interaction — see the full Watercress list.

See the full Watercress interactions page

See every supplement checked against Phenylephrine, ranked by severity

Evidence & sources

Watercress References

The 34 references that drive our Watercress 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.

Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
Leclercq I, Desager JP, Horsmans Y. Inhibition of chlorzoxazone metabolism, a clinical probe for CYP2E1, by a single ingestion of watercress. Clin Pharmacol Ther 1998;64:144-9. PubMed
Bolton-Smith C, Price RJ, Fenton ST, et al. Compilation of a provisional UK database for the phylloquinone (vitamin K1) content of foods. Br J Nutr 2000;83:389-99.
Rondelaud, D., Dreyfuss, G., Bouteille, B., and Darde, M. L. Changes in human fasciolosis in a temperate area: about some observations over a 28-year period in central France. Parasitol.Res 2000;86(9):753-757. PubMed
Sanchez-Sosa, S., Rojas-Ortega, S., Reed-San Roman, G., and Torres-Santana, M. A. [Massive hepatobiliary fascioliasis]. Rev Gastroenterol.Mex. 2000;65(4):179-183.
van Daele, P. L., Madretsma, G. S., and van Agtmael, M. A. [Stomach ache and fever after consumption of watercress in Turkey: fascioliasis]. Ned.Tijdschr.Geneeskd. 9-29-2001;145(39):1896-1899.
Cosme, A., Ojeda, E., Cilla, G., Torrado, J., Alzate, L., Beristain, X., Orive, V., and Arenas, J. [Fasciola hepatica. study of a series of 37 patients]. Gastroenterol.Hepatol. 2001;24(8):375-380.
Martinez-Bebert, K., Rodriguez-Baez, R., Pila-Perez, R., Pila-Pelaez, R., and Tamakloe, K. [Hepatic hematoma caused by fascioliasis]. Gac.Med Mex. 2002;138(3):271-274.
Dreyfuss, G., Vignoles, P., Abrous, M., and Rondelaud, D. Unusual snail species involved in the transmission of Fasciola hepatica in watercress beds in central France. Parasite 2002;9(2):113-120.
Christmann, M., Henrich, R., Mayer, G., and Ell, C. [Infection with fasciola hepatica causing elevated liver-enzyme results and eosinophilia - serologic and endoscopic diagnosis and therapy]. Z.Gastroenterol. 2002;40(9):801-806.
Cosme, A., Ojeda, E., Poch, M., Bujanda, L., Castiella, A., and Fernandez, J. Sonographic findings of hepatic lesions in human fascioliasis. J Clin Ultrasound 2003;31(7):358-363. PubMed
Sapunar, J., Latorre, R., Guerra, M., and Defilippi, C. [Clinical considerations on 2 cases of hepatic fascioliasis. Importance of the imaging examinations]. Bol.Chil.Parasitol. 1992;47(3-4):70-76.
de Gorgolas, M., Torres, R., Verdejo, C., Garay, J., Robledo, A., Ponte, M. C., and Fernandez Guerrero, M. L. [Fasciola hepatica infestation. Biopathology and new diagnostic and therapeutic aspects]. Enferm.Infecc.Microbiol.Clin 1992;10(9):514-519.
Carrada-Bravo, T. [Fascioliasis: diagnosis, epidemiology and treatment]. Rev Gastroenterol.Mex. 2003;68(2):135-142.
Yilmaz, H. and Godekmerdan, A. Human fasciolosis in Van province, Turkey. Acta Trop. 2004;92(2):161-162.
Dobrucali, A., Yigitbasi, R., Erzin, Y., Sunamak, O., Polat, E., and Yakar, H. Fasciola hepatica infestation as a very rare cause of extrahepatic cholestasis. World J Gastroenterol. 10-15-2004;10(20):3076-3077. PubMed
Alvarez-Chacon, R., Garcia-Rosales, J. J., de la Cruz-Otero MC, Wong-Chio, M., Cabrera-Bravo, M., Gomez-Gomez, J. V., and Gamez-Aranda, V. [Fascioliasis in children. A study of 10 cases]. Bol.Med Hosp.Infant Mex. 1992;49(6):365-371.
Mailles, A., Capek, I., Ajana, F., Schepens, C., Ilef, D., and Vaillant, V. Commercial watercress as an emerging source of fascioliasis in Northern France in 2002: results from an outbreak investigation. Epidemiol.Infect. 2006;134(5):942-945.
Cruz, Lopez O., Adan, Pimentel A., Tamariz Cruz, O. J., Munoz, Lopez A., Cruz Lopez, M. C., Cruz Lopez, M. E., and Munoz, Lopez S. [Hepatic fasciolasis diagnosed in state phase]. Rev Gastroenterol Mex. 2006;71(1):59-62.
el Shazly, A. M., Handousa, A. E., Youssef, M. E., Rizk, H., and Hamouda, M. M. Human fascioliasis: a parasitic health problem in Dakahlia Governorate, Egypt. J Egypt.Soc Parasitol. 1991;21(2):553-559.
Cosme, A., Alzate, L., Orive, V., Recasens, M., Torrado, J., Ruiz, I., and Arenas, J. [Laparoscopic findings in liver fascioliasis. Study of 13 cases]. Rev Esp.Enferm.Dig. 1990;78(6):359-362.
Diaz, J., Pina, B., Lastre, M., Rivera, L., and Perez, O. [Epidemic human fascioliasis. Cuba 1983. VI. Clinical study of 40 children in the Hospital Provincial of Sagua la Grande]. G.E.N. 1990;44(4):385-388.
Borie, C., Corona, S., Garin, A., Olea, P., Salcedo, M., Perez, C., and Apt, W. [A family outbreak of acute hepatic fascioliasis]. Rev Med Chil. 1990;118(1):67-72.
Diamond, S. P., Wiener, S. G., and Marks, J. G., Jr. Allergic contact dermatitis to nasturtium. Dermatol.Clin. 1990;8(1):77-80. DOI
Delasalle, P., Beytout, J., Cambon, M., and Bommelaer, G. [Distomatosis: diagnosis and treatment]. Rev Prat. 1-21-1990;40(3):230-236.
Rivera, J. V. and Bermudez, R. H. Radionuclide imaging of the liver in human fascioliasis. Clin Nucl.Med 1984;9(8):450-453. PubMed
Croese, J., Chapman, G., and Gallagher, N. D. Evolution of fascioliasis after eating wild watercress. Aust.N.Z.J.Med. 1982;12(5):525-527. PubMed
Bendezu, P., Frame, A., and Hillyer, G. V. Human fascioliasis in Corozal, Puerto Rico. J Parasitol. 1982;68(2):297-299. DOI
Derrick, E. and Darley, C. Contact dermatitis to nasturtium. Br.J Dermatol 1997;136(2):290-291. PubMed
Narain, K., Biswas, D., Rajguru, S. K., and Mahanta, J. Human distomatosis due to Fasciola hepatica infection in Assam, India. J Commun.Dis 1997;29(2):161-165.
Brinker, F. Herb Contraindications and Drug Interactions. 1998;2nd edition.
Gruenwald, J. PDR for Herbal Medicines. 1998;1st ed.
Clemente M, Miguel MD, Felipe KB, et al. Effect of watercress extract supplementation on lipid profile and oxidative stress markers in overweight people with physical disability: A randomized, double-blind, and placebo-controlled trial. Phytother Res. 202 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 Watercress and Phenylephrine Together: Common Questions

Is it safe to take Watercress with Phenylephrine?

We do not list a known interaction between Watercress and Phenylephrine. 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.

Do Watercress and Phenylephrine have any of the same side effects?

Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.

How was the Watercress and Phenylephrine combination checked?

Interactions in our licensed database are recorded against drug classes. Phenylephrine is filed under 5 classifications, and Watercress has documented interactions with 3 drug classes — none of Phenylephrine'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 Watercress interact with any other medications?

Yes. Watercress has 6 documented drug interactions in our database — Phenylephrine 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 Phenylephrine interact with any supplements?

Yes. Phenylephrine has documented interactions with 81 supplements in our database — Watercress is not one of them. The Phenylephrine 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

Watercress monograph Uses, safety profile, and every drug interaction in one place Phenylephrine drug information The full plain-English guide to this medication Phenylephrine supplement interactions Every supplement checked against Phenylephrine, 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 34 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenylephrine and Watercress?

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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.