Drug & supplement interaction

Watercress + Istradefylline

Istradefylline brand name: Nourianz.

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 Watercress and Istradefylline 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 Istradefylline

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 Istradefylline 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 Istradefylline and Watercress? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Istradefylline

Interactions in our licensed database are recorded against drug classes, not just single drug names. Istradefylline is filed under 2 classifications — cytochrome p450 3a4 (cyp3a4) substrates, oral 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 Istradefylline’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 — Istradefylline 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. Istradefylline)
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 Istradefylline May Share Several of the Same Side Effects

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.

  • Diarrhea 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
    1. 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
    2. 85574. Yilmaz, H. and Godekmerdan, A. Human fasciolosis in Van province, Turkey. Acta Trop. 2004;92(2):161-162.
    3. 85573. Carrada-Bravo, T. [Fascioliasis: diagnosis, epidemiology and treatment]. Rev Gastroenterol.Mex. 2003;68(2):135-142.
    4. 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
    5. 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.
    6. 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.

    Istradefylline

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

  • A skin rash Additional detail

    Watercress

    “Orally, watercress is well-tolerated when consumed in food amounts. There is limited reliable information available about the adverse effects of watercress when used in medicinal amounts. When excessive doses are used, watercress can cause gastrointestinal irritation.”

    Watercress · Natural Medicines adverse-effect record, reported in dermatitis.

    6 sources cited
    1. 85599. Gruenwald, J. PDR for Herbal Medicines. 1998;1st ed.
    2. 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
    3. 85574. Yilmaz, H. and Godekmerdan, A. Human fasciolosis in Van province, Turkey. Acta Trop. 2004;92(2):161-162.
    4. 85573. Carrada-Bravo, T. [Fascioliasis: diagnosis, epidemiology and treatment]. Rev Gastroenterol.Mex. 2003;68(2):135-142.
    5. 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
    6. 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.

    “Topically, watercress can cause contact dermatitis, resulting in hives, rash, itching, or swollen skin.”

    Watercress · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 85594. Derrick, E. and Darley, C. Contact dermatitis to nasturtium. Br.J Dermatol 1997;136(2):290-291. PubMed
    2. 85587. Diamond, S. P., Wiener, S. G., and Marks, J. G., Jr. Allergic contact dermatitis to nasturtium. Dermatol.Clin. 1990;8(1):77-80. DOI

    Istradefylline

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

Reported for Watercress but not commonly for Istradefylline: stomach pain, kidney problems, hives and vomiting.

Effects for Istradefylline 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 5,920 voluntary FDA FAERS reports for Istradefylline 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

Everything else you take

See Every Supplement That Interacts With Istradefylline

This page covers Watercress only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Istradefylline page lists 138 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 94 moderate · 41 minor.

From our pharmacist’s overview on the Istradefylline page

“Istradefylline (Nourianz) is added to levodopa to trim the daily 'off' time of Parkinson's disease, and its supplement list deserves genuine care. Most of the 138 ingredients here can change how the liver enzyme CYP3A4 handles the drug, so blood levels may drift too high or too low.”

Reviewed by 2 · Jul 18, 2026

Open the Istradefylline 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 Istradefylline, 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 Istradefylline 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%

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

29 days ago today
Medication Istradefylline
Top half

#755 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 September 13, 2026. The Watercress and Istradefylline 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 Watercress

What is Watercress?

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 Istradefylline

What Is Istradefylline Used For?

Brand name: Nourianz

Nourianz (istradefylline) is used alongside levodopa/carbidopa in adults with Parkinson's disease. Specifically, it is meant to reduce 'off' episodes — periods when levodopa stops working as well and Parkinson's symptoms return or worsen.

It is an add-on therapy only; it is not used alone or as a replacement for levodopa/carbidopa.

Most-Reported Side Effects for Istradefylline

From FAERS, the FDA’s public side-effect reporting system (5,920 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Hallucination 608 reports
Dyskinesia 482 reports
Dizziness 421 reports
Constipation 353 reports
Fall 344 reports
See full Istradefylline 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 Istradefylline, 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.

  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. 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
  4. 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.
  5. 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
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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
  13. 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.
  14. 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.
  15. Carrada-Bravo, T. [Fascioliasis: diagnosis, epidemiology and treatment]. Rev Gastroenterol.Mex. 2003;68(2):135-142.

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 Istradefylline Together: Common Questions

Is it safe to take Watercress with Istradefylline?
We do not list a known interaction between Watercress and Istradefylline. 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 Istradefylline have any of the same side effects?
Yes — our sources link each of them separately to 2 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 Istradefylline combination checked?
Interactions in our licensed database are recorded against drug classes. Istradefylline is filed under 2 classifications, and Watercress has documented interactions with 3 drug classes — none of Istradefylline'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 — Istradefylline 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 Istradefylline interact with any supplements?
Yes. Istradefylline has documented interactions with 138 supplements in our database — Watercress is not one of them. The Istradefylline 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 Istradefylline drug information The full plain-English guide to this medication Istradefylline supplement interactions Every supplement checked against Istradefylline, 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

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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.