Drug & supplement interaction

Black Root + Hydralazine, Hydrochlorothiazide, Reserpine

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

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

Black Root has a moderate interaction with Hydralazine, Hydrochlorothiazide, Reserpine. Overuse of black root might compound diuretic-induced potassium loss.There is some concern that people taking black root along with potassium depleting diuretics might have an increased risk for hypokalemia.

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

Black Root and Hydralazine, Hydrochlorothiazide, Reserpine

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

Moderate

DIURETIC DRUGS

Why this applies to Hydralazine, Hydrochlorothiazide, Reserpine

Hydralazine, Hydrochlorothiazide, Reserpine falls under DIURETIC DRUGS — the group Black Root interacts with.

Overuse of black root might compound diuretic-induced potassium loss.There is some concern that people taking black root along with potassium depleting diuretics might have an increased risk for hypokalemia. Initiation of potassium supplementation or an increase in potassium supplement dose may be necessary for some patients. Some diuretics that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide), and others.
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

This combination pill (Ser-Ap-Es) includes hydrochlorothiazide, a water pill that already nudges your body to lose potassium through the urine. Black Root has a reputation as a strong laxative, and frequent loose stools can flush out potassium too. Used together in large or repeated amounts, the worry is that your potassium could dip too low, a state called hypokalemia.

Low potassium can leave you feeling weak, crampy, or tired, and may cause an irregular heartbeat, which matters even more here since this medicine is treating blood pressure. To be honest, this concern is theoretical and based on how these things work, not on solid studies. Still, please check with your pharmacist or doctor before adding Black Root, and don't change your medication on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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

Black Root Also Interacts With Other Medications

Black Root has 77 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.

Moderate 77 No known interaction 2,753 (incl. Hydralazine, Hydrochlorothiazide, Reserpine)
Taking anything else?

Check Another of Your Medications Against Black Root

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

Everything else you take

See Every Supplement That Interacts With Hydralazine, Hydrochlorothiazide, Reserpine

This page covers Black Root 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 Black Root as Part of a Dietary Supplement Product? Check It for Interactions

We hold 41 real supplement products containing Black Root, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Root. Your product may carry other ingredients that interact with Hydralazine, Hydrochlorothiazide, Reserpine too, on top of Black Root — 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 Black Root 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 Black Root
Top half

#421 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 Black Root

What is Black Root?

  • Constipation
  • Liver and gallbladder complaints
  • Digestive upset
  • Stimulating bile flow

Black Root is a traditional North American herb that was historically used as a strong laxative and to support digestion and liver function. There is very little modern scientific evidence to support these uses, and the fresh root can be toxic, so it should be used cautiously, if at all, and never during pregnancy or breastfeeding.

Read the full Black Root monograph & all interactions
Keep checking

Other Drugs & Black Root

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

0Major
77Moderate
0Minor
2,752No known interaction
77 Moderate 2,752 No interaction
Moderate

77 interactions

Showing 60 of 77 moderate interactions — see all 77 on the Black Root page.

No interaction 2,752 drugs checked — show the list

We also checked Black Root 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 Black Root list.

See the full Black Root 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
Black Root 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 Black Root and Hydralazine, Hydrochlorothiazide, Reserpine Together: Common Questions

Can you take Black Root with Hydralazine, Hydrochlorothiazide, Reserpine?
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 Black Root and Hydralazine, Hydrochlorothiazide, Reserpine 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

Still Have a Question About Hydralazine, Hydrochlorothiazide, Reserpine and Black Root?

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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.