Drug & supplement interaction

Yellow Dock + Hydralazine, Hydrochlorothiazide, Reserpine

Hydralazine, Hydrochlorothiazide, Reserpine brand names: Ser-Ap-Es, Unipres, Uniserp.

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

Yellow Dock has a major interaction with Hydralazine, Hydrochlorothiazide, Reserpine. Theoretically, yellow dock might increase the risk of hypokalemia when taken with diuretics.

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

Yellow Dock and Hydralazine, Hydrochlorothiazide, Reserpine

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

Major

DIURETIC DRUGS

Why this applies to Hydralazine, Hydrochlorothiazide, Reserpine

Hydralazine, Hydrochlorothiazide, Reserpine falls under DIURETIC DRUGS — the group Yellow Dock interacts with.

Theoretically, yellow dock might increase the risk of hypokalemia when taken with diuretics.
When yellow dock is used chronically or in large amounts, hypokalemia may occur, and overuse of yellow dock might compound diuretic-induced potassium loss.
Severity Major Likelihood Probable Evidence D

Interaction 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..

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

Here's the thing to keep an eye on with this combination pill (Ser-Ap-Es and similar). The hydrochlorothiazide part is a water pill that already nudges your body to lose potassium through the urine. Yellow dock root contains the same family of laxative compounds found in senna, and when used heavily or for a long stretch, those can pull potassium out too. Stack the two together and your potassium could drop lower than it should.

Low potassium can leave you feeling weak, crampy, or tired, and in some cases throw off your heart rhythm. This concern is mostly theoretical and tied to chronic or large doses of yellow dock, not an occasional cup of tea. Still, before using it regularly, please check in with your pharmacist or doctor so they can keep an eye on your potassium.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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

Yellow Dock Also Interacts With Other Medications

Yellow Dock has 75 major, 2 moderate known drug interactions in our database — the Hydralazine, Hydrochlorothiazide, Reserpine one above is one of them. If you take anything else, check it against the full list below.

Major 75 Moderate 2 No known interaction 2,753 (incl. Hydralazine, Hydrochlorothiazide, Reserpine)
Taking anything else?

Check Another of Your Medications Against Yellow Dock

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

Everything else you take

See Every Supplement That Interacts With Hydralazine, Hydrochlorothiazide, Reserpine

This page covers Yellow Dock only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydralazine, Hydrochlorothiazide, Reserpine page lists 231 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), Asarabacca (major) and Dolomite (major).

By severity: 10 major · 196 moderate · 25 minor.

From our pharmacist’s overview on the Hydralazine, Hydrochlorothiazide, Reserpine page

“Ser-Ap-Es combines three blood pressure drugs, hydralazine, hydrochlorothiazide, and reserpine, so this list deserves real attention before you add a supplement. Most of the 231 ingredients on file either push blood pressure down further than intended or pile onto the diuretic and drag potassium and fluid levels with it.”

Reviewed by 2 · Jul 18, 2026

Open the Hydralazine, Hydrochlorothiazide, Reserpine interaction page

One more smart check

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

We hold 753 real supplement products containing Yellow Dock, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Yellow Dock. Your product may carry other ingredients that interact with Hydralazine, Hydrochlorothiazide, Reserpine too, on top of Yellow Dock — 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 Yellow Dock and Hydralazine, Hydrochlorothiazide, Reserpine 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 Yellow Dock
Top 25%

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

29 days ago today
Medication Hydralazine, Hydrochlorothiazide, Reserpine
Steady interest

#1,738 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 Yellow Dock

What is Yellow Dock?

  • Constipation
  • Digestive support
  • Skin conditions
  • Iron-deficiency or 'blood-building' tonic
  • Liver and detox support

Yellow dock is a traditional herb used mostly as a mild laxative and a digestive and skin tonic. Good-quality human studies are lacking, so its benefits are largely unproven, and its naturally occurring oxalates and anthraquinones mean it should be used cautiously and not long-term.

Read the full Yellow Dock monograph & all interactions
Keep checking

Other Drugs & Yellow Dock

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

75Major
2Moderate
0Minor
2,752No known interaction
75 Major 2 Moderate 2,752 No interaction
Major

75 interactions

Showing 60 of 75 major interactions — see all 75 on the Yellow Dock page.

Moderate

2 interactions

No interaction 2,752 drugs checked — show the list

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

Showing the 60 most looked-up of 2,752 medications checked with no known interaction — see the full Yellow Dock list.

See the full Yellow Dock interactions page
See every supplement checked against Hydralazine, Hydrochlorothiazide, Reserpine, 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
Yellow Dock monograph › Uses, safety, and every drug interaction in one place Hydralazine, Hydrochlorothiazide, Reserpine supplement interactions › Every supplement checked against Hydralazine, Hydrochlorothiazide, Reserpine, 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 Yellow Dock and Hydralazine, Hydrochlorothiazide, Reserpine Together: Common Questions

Can you take Yellow Dock with Hydralazine, Hydrochlorothiazide, Reserpine?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Yellow Dock and Hydralazine, Hydrochlorothiazide, Reserpine interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Hydralazine, Hydrochlorothiazide, Reserpine and Yellow Dock?

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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.