Drug & supplement interaction

Parsley + Chlorthalidone, Clonidine

Chlorthalidone, Clonidine brand names: Clorpres, Combipres.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Parsley has a moderate interaction with Chlorthalidone, Clonidine. Theoretically, parsley might enhance or interfere with the effects of diuretic drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Parsley and Chlorthalidone, Clonidine

Here is the interaction we found between these two, with the evidence behind it.

Moderate

DIURETIC DRUGS

Why this applies to Chlorthalidone, Clonidine

Chlorthalidone, Clonidine falls under DIURETIC DRUGS — the group Parsley interacts with.

Theoretically, parsley might enhance or interfere with the effects of diuretic drugs.
Animal research suggests that parsley seed extract increases urine elimination. Parsley leaf and root might also interfere with diuretic therapy due their purported aquaretic effects.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with this combo product, which pairs chlorthalidone (a water pill, or diuretic) with clonidine (a blood pressure medicine). Parsley has a long folk reputation as a natural diuretic, and some animal studies hint that concentrated parsley seed extract may nudge the kidneys to release more urine. So in theory, piling a parsley supplement on top of chlorthalidone could push your fluid loss a little further than intended.

I want to be straight with you: this is only a theoretical concern based on pharmacology, not proven in people. If it mattered, you might notice more dehydration signs, like dizziness, lightheadedness when standing, or a lower blood pressure than usual. Eating parsley as a food garnish is almost certainly fine. Concentrated capsules or seed extracts are where I'd pause and check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Robbers JE, Tyler VE. Tyler's Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York, NY: The Haworth Herbal Press, 1999.
  2. Kreydiyyeh, S. I. and Usta, J. Diuretic effect and mechanism of action of parsley. J Ethnopharmacol 2002;79(3):353-357. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Parsley Also Interacts With Other Medications

Parsley has 442 moderate known drug interactions in our database — the Chlorthalidone, Clonidine one above is one of them. If you take anything else, check it against the full list below.

Moderate 442 No known interaction 2,388 (incl. Chlorthalidone, Clonidine)
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.

Everything else you take

See Every Supplement That Interacts With Chlorthalidone, Clonidine

This page covers Parsley only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Chlorthalidone, Clonidine page lists 224 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Dolomite (major) and Lithium (major).

By severity: 8 major · 192 moderate · 24 minor.

From our pharmacist’s overview on the Chlorthalidone, Clonidine page

“Clorpres pairs chlorthalidone, a diuretic, with clonidine, and both work by lowering blood pressure, so the 224 supplements and herbs on file deserve more than a casual read. Most either push blood pressure lower than intended or, like tyramine, fight the medication and let pressure climb.”

Reviewed by 2 · Jul 18, 2026

Open the Chlorthalidone, Clonidine 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. Your product may carry other ingredients that interact with Chlorthalidone, Clonidine too, on top of Parsley — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Parsley and Chlorthalidone, Clonidine 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%

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

29 days ago today
Medication Chlorthalidone, Clonidine
Steady interest

#1,585 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.

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.

Read the full Parsley monograph & all interactions
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
442Moderate
0Minor
2,387No known interaction
442 Moderate 2,387 No interaction
Moderate

442 interactions

Showing 60 of 442 moderate interactions — see all 442 on the Parsley page.

No interaction 2,387 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 2,387 medications checked with no known interaction — see the full Parsley list.

See the full Parsley interactions page
See every supplement checked against Chlorthalidone, Clonidine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Parsley monograph › Uses, safety, and every drug interaction in one place Chlorthalidone, Clonidine supplement interactions › Every supplement checked against Chlorthalidone, Clonidine, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Parsley and Chlorthalidone, Clonidine Together: Common Questions

Can you take Parsley with Chlorthalidone, Clonidine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Parsley and Chlorthalidone, Clonidine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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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.