Drug & supplement interaction

Licorice + 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

Hydralazine, Hydrochlorothiazide, Reserpine falls into 2 drug categories that Licorice can interact with; the most serious is rated moderate. Theoretically, licorice might reduce the effects of antihypertensive drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Licorice and Hydralazine, Hydrochlorothiazide, Reserpine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Licorice interacts with whole categories of medication. Hydralazine, Hydrochlorothiazide, Reserpine falls into 2 of those categories, so it can interact with Licorice in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 2

Why this applies to Hydralazine, Hydrochlorothiazide, Reserpine

Hydralazine, Hydrochlorothiazide, Reserpine falls under ANTIHYPERTENSIVE DRUGS — the group Licorice interacts with.

Theoretically, licorice might reduce the effects of antihypertensive drugs.
In human research, licorice increases blood pressure in a dose-dependent manner.
Severity Moderate Likelihood Possible Evidence B

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) is a blood pressure medicine. It blends hydralazine to relax your vessels, hydrochlorothiazide (a water pill) to flush out extra sodium and fluid, and reserpine to calm overactive nerve signals. Here's the catch with licorice: the glycyrrhizin in regular licorice makes your body hold onto sodium and water while dumping potassium, which actually nudges blood pressure up. That works directly against what your medicine is trying to do.

So licorice can blunt your blood pressure control, and because your pill already lowers potassium through the water pill, licorice may push potassium even lower, which can cause muscle cramps, weakness, or an irregular heartbeat. Food amounts in candy are usually fine, but concentrated supplements or daily black licorice are the worry. Deglycyrrhizinated (DGL) licorice avoids this problem. Please check with your pharmacist or doctor before using it.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sigurjonsdottir HA, Ragnarsson J, Franzson L, Sigurdsson G. Is blood pressure commonly raised by moderate consumption of liquorice? J Hum Hypertens 1995;9:345-8.
  2. Sigurjonsdottir HA, Franzson L, Manhem K, et al. Liquorice-induced rise in blood pressure: a linear dose-response relationship. J Hum Hypertens 2001;15:549-52. PubMed
  3. Koster, M. and David, G. K. Reversible severe hypertension due to licorice ingestion. N Engl J Med 1968;278(25):1381-1383. PubMed
Moderate

DIURETIC DRUGS

2 of 2

Hydralazine, Hydrochlorothiazide, Reserpine also falls under DIURETIC DRUGS.

Theoretically, concomitant use of licorice with diuretic drugs might increase the risk of hypokalemia.
Overuse of licorice might compound diuretic-induced potassium loss. In one case report, a 72-year-old male with a past medical history of hypertension, type 2 diabetes, hyperlipidemia, arrhythmia, stroke, and hepatic dysfunction was hospitalized with severe hypokalemia and uncontrolled hypertension due to pseudohyperaldosteronism. This was thought to be provoked by concomitant daily consumption of a product containing 225 mg of glycyrrhizin, a constituent of licorice, and hydrochlorothiazide 12.5 mg for 1 month.
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 includes hydrochlorothiazide, a water pill that already lowers your potassium. Here's the catch with licorice: the glycyrrhizin in regular licorice makes your body hold onto sodium and dump even more potassium. Stack those two together and your potassium can drop low enough to cause muscle weakness, cramps, tiredness, or an irregular heartbeat, which matters since this medicine is often used in people who already have heart rhythm concerns.

To be fair, this is based on limited, mostly anecdotal evidence (one case report), so it's a possible concern rather than a sure thing, and it's tied to regular, concentrated licorice taken daily, not an occasional candy. Deglycyrrhizinated (DGL) licorice doesn't carry this risk. Please check with your pharmacist or doctor before using licorice regularly.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Yoshida S, Takayama Y. Licorice-induced hypokalemia as a treatable cause of dropped head syndrome. Clin Neurol Neurosurg 2003;105:286-7.. PubMed
  2. Heidemann HT, Kreuzfelder E. Hypokalemic rhabdomyolysis with myoglobinuria due to licorice ingestion and diuretic treatment. Klin Wochenschr 1983;61:303-5. PubMed
  3. Hukkanen J, Ukkola O, Savolainen MJ. Effects of low-dose liquorice alone or in combination with hydrochlorothiazide on the plasma potassium in healthy volunteers. Blood Press 2009;18:192-5. PubMed
  4. Goultschin, J., Palmon, S., Shapira, L., Brayer, L., and Gedalia, I. Effect of glycyrrhizin-containing toothpaste on dental plaque reduction and gingival health in humans. A pilot study. J Clin Periodontol 1991;18(3):210-212. PubMed
  5. Fan ZJ, Liu JM, Li XX, et al. Glycyrrhizin-Induced Pseudohyperaldosteronism: A Case Report. Chin J Integr Med 2022. 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

Licorice Also Interacts With Other Medications

Licorice has 976 moderate, 63 minor known drug interactions in our database — the Hydralazine, Hydrochlorothiazide, Reserpine one above is among them. If you take anything else, check it against the full list below.

Moderate 976 Minor 63 No known interaction 1,791 (incl. Hydralazine, Hydrochlorothiazide, Reserpine)
Taking anything else?

Check Another of Your Medications Against Licorice

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

From our Q&A

Questions About Licorice or Hydralazine, Hydrochlorothiazide, Reserpine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Licorice or Hydralazine, Hydrochlorothiazide, Reserpine, 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 Hydralazine, Hydrochlorothiazide, Reserpine

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

We hold 4,721 real supplement products containing Licorice, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Licorice. Your product may carry other ingredients that interact with Hydralazine, Hydrochlorothiazide, Reserpine too, on top of Licorice — 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 Licorice 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 Licorice
Top 5%

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

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

#2,088 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 Licorice

What is Licorice?

Licorice
  • Sore throat and cough
  • Heartburn and stomach upset
  • Mouth ulcers and digestive complaints
  • Inflammation
  • Traditional tonic/adrenal support

Licorice root is a traditional remedy used for sore throats, coughs, and digestive complaints, but solid human evidence is limited for most uses. Regular licorice contains glycyrrhizin, which can raise blood pressure and lower potassium when taken in large amounts or for a long time, so deglycyrrhizinated (DGL) products are often preferred. Talk to your pharmacist or doctor before using it, especially if you have high blood pressure, heart, or kidney problems.

Read the full Licorice monograph & all interactions
Keep checking

Other Drugs & Licorice

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

0Major
976Moderate
63Minor
1,790No known interaction
976 Moderate 63 Minor 1,790 No interaction
Moderate

976 interactions

Showing 60 of 976 moderate interactions — see all 976 on the Licorice page.

Minor

63 interactions

Showing 60 of 63 minor interactions — see all 63 on the Licorice page.

No interaction 1,790 drugs checked — show the list

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

Showing the 60 most looked-up of 1,790 medications checked with no known interaction — see the full Licorice list.

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

Can you take Licorice 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.
Why are there 2 interactions listed for Licorice and Hydralazine, Hydrochlorothiazide, Reserpine?
Hydralazine, Hydrochlorothiazide, Reserpine belongs to more than one drug category, and Licorice interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Licorice 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 Licorice?

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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.