Drug & supplement interaction

Black Horehound + Felodipine

Felodipine brand names: Plendil, Renedil.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Black Horehound and Felodipine 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 label for Felodipine states a food rule worth keeping to.

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Interaction report

Black Horehound and Felodipine

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 Felodipine and Black Horehound 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.

Black Horehound safety at a glance

Black Horehound overall Use caution Limited safety data exist, so use cautiously and talk to a pharmacist first.
Pregnancy Likely Unsafe When used orally; black horehound may affect the menstrual cycle. There is insufficient reliable information available about the safety of black horehound used... Read the full pregnancy detail
Breastfeeding Avoid Safety is unknown, so avoid use while breastfeeding.

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 Felodipine and Black Horehound? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Felodipine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Felodipine is filed under 5 classifications — including calcium channel blockers, antihypertensive drugs, cytochrome p450 3a4 (cyp3a4) substrates. Black Horehound has documented interactions with 1 drug class — the most serious being dopamine agonists (moderate) — and none of Felodipine’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

Black Horehound Does Interact With Other Medications

Black Horehound has 23 moderate known drug interactions in our database — Felodipine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 23 No known interaction 2,807 (incl. Felodipine)
Taking anything else?

Check Another of Your Medications Against Black Horehound

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

What to actually watch for

What Felodipine’s Own FDA Label Lists

This is not an interaction — none of it involves Black Horehound. These are the most notable effects listed in the ADVERSE REACTIONS section of Felodipine’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • Pain or burning when passing urine Worth acting on
  • A heart attack Worth acting on
  • Shortness of breath Worth acting on mentioned in 8.8% of FDA reports for Felodipine
  • Fainting Worth acting on
  • An irregular heartbeat Worth acting on
  • Chest pain Worth acting on
  • Low mood Worth acting on
  • Anemia Worth acting on
  • A severe allergic reaction Worth acting on
  • Hives Worth acting on

Showing the 10 most notable of 44 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Felodipine. Read the label on DailyMed › Where a percentage is shown, it is the share of 11,328 voluntary FDA FAERS reports for Felodipine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Black Horehound’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Black Horehound side to compare — that is a limit of the record, not a statement that Black Horehound has no side effects.

Special populations

Black Horehound in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally; black horehound may affect the menstrual cycle. There is insufficient reliable information available about the safety of black horehound used topically or rectally during pregnancy.

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

How to take them

Some Felodipine Products Have a Food Rule — Black Horehound Should Not Break It

At least one FDA label for a product containing Felodipine says to take it on an empty stomach. Most supplements — Black Horehound included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Felodipine on its own and move Black Horehound to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Felodipine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

Felodipine should regularly be taken either without food or with a light meal (see CLINICAL PHARMACOLOGY, Pharmacokinetics and Metabolism ).

From the Dosage and Administration section of the FDA label we read for Felodipine — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Black Horehound or Felodipine

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

This page covers Black Horehound only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Felodipine page lists 232 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), Coleus (major) and Grapefruit (major).

By severity: 8 major · 182 moderate · 42 minor.

From our pharmacist’s overview on the Felodipine page

“Felodipine (Plendil) is a blood pressure medicine broken down by the CYP3A4 enzyme, which is why 232 supplements and foods have an interaction on file, eight of them rated major. This list deserves real care.”

Reviewed by 2 · Jul 18, 2026

Open the Felodipine interaction page

How much people look this up

Where Black Horehound and Felodipine 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 Horehound
Steady interest

#1,078 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Felodipine
Top half

#1,193 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 Black Horehound reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Black Horehound and Felodipine 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 Black Horehound

What is Black Horehound?

Black Horehound
  • Nausea and vomiting
  • Anxiety and nervous tension
  • Sleep problems
  • Mild digestive upset
  • Coughs and respiratory complaints

Black horehound is a traditional European herb mainly used for nausea, mild anxiety, and digestive upset, but high-quality human studies are lacking, so its effectiveness is largely unproven. It has a strong, unpleasant smell and taste, and its safety has not been well studied, so it should be avoided in pregnancy and breastfeeding and used cautiously by everyone else.

Ballota nigra · Lamiaceae · Above-ground parts (flowering tops and leaves) · Tea (infusion), liquid extract, tincture, capsules

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

Black Horehound: dosing

There is no well-established, standardized dose for black horehound. Traditional use has involved teas made from the dried herb and liquid extracts or tinctures, but reliable dosing from quality human studies is not available.If you choose to use a product, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Black Horehound monograph & all interactions
Medication

About Felodipine

What Is Felodipine Used For?

Brand names: Plendil, Renedil

Felodipine extended-release tablets are used to treat high blood pressure (hypertension). Lowering blood pressure reduces the risk of serious events like stroke and heart attack. Felodipine may be used alone or combined with other blood pressure medicines.

Keeping blood pressure under control is part of a broader approach to heart health that can include managing cholesterol, blood sugar, and lifestyle factors like diet, exercise, and not smoking.

Most-Reported Side Effects for Felodipine

From FAERS, the FDA’s public side-effect reporting system (11,328 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 1,108 reports
Dyspnea 1,002 reports
Dizziness 1,000 reports
Diarrhea 887 reports
Nausea 887 reports
See full Felodipine drug information
Keep checking

Other Drugs & Black Horehound

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

0Major
23Moderate
0Minor
2,806No known interaction
23 Moderate 2,806 No interaction
Moderate

23 interactions

No interaction 2,806 drugs checked — show the list

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

Showing the 60 most looked-up of 2,806 medications checked with no known interaction — see the full Black Horehound list.

See the full Black Horehound interactions page
See every supplement checked against Felodipine, ranked by severity
Evidence & sources

Black Horehound References

The 2 references that drive our Black Horehound 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. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Daels-Rakotoarison DA, Seidel V, Gressier B, et al. Neurosedative and antioxidant activities of phenylpropanoids from Ballota nigra. Arzneimittelforschung 2000;50:16-23. 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 Black Horehound and Felodipine Together: Common Questions

Is it safe to take Black Horehound with Felodipine?
We do not list a known interaction between Black Horehound and Felodipine. 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.
Should I take Black Horehound and Felodipine at the same time of day?
At least one FDA label for a product containing Felodipine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Felodipine on its own and move Black Horehound to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Black Horehound and Felodipine combination checked?
Interactions in our licensed database are recorded against drug classes. Felodipine is filed under 5 classifications, and Black Horehound has documented interactions with 1 drug class — none of Felodipine'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 Black Horehound interact with any other medications?
Yes. Black Horehound has 23 documented drug interactions in our database — Felodipine 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 Felodipine interact with any supplements?
Yes. Felodipine has documented interactions with 232 supplements in our database — Black Horehound is not one of them. The Felodipine 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

Black Horehound monograph Uses, safety profile, and every drug interaction in one place Felodipine drug information The full plain-English guide to this medication Felodipine supplement interactions Every supplement checked against Felodipine, 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Felodipine and Black Horehound?

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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.