Drug & supplement interaction

Procaine + Fosinopril, Hydrochlorothiazide

Fosinopril, Hydrochlorothiazide brand name: Monopril HCT.

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

Procaine has a moderate interaction with Fosinopril, Hydrochlorothiazide. A metabolite of procaine, aminobenzoic acid, can antagonize the effect of sulfonamides.

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

Procaine and Fosinopril, Hydrochlorothiazide

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

Moderate

SULFONAMIDE ANTIBIOTICS

Why this applies to Fosinopril, Hydrochlorothiazide

Fosinopril, Hydrochlorothiazide falls under SULFONAMIDE ANTIBIOTICS — the group Procaine interacts with.

A metabolite of procaine, aminobenzoic acid, can antagonize the effect of sulfonamides. Theoretically, procaine might also reduce sulfonamide activity. Some sulfonamides include sulfamethoxazole (Gantanol), sulfasalazine (Azulfidine), sulfisoxazole (Gantrisin), and trimethoprim/sulfamethoxazole (Bactrim, Septra).
Severity Moderate 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 something worth clearing up. The interaction in our database is really meant for sulfonamide antibiotics like Bactrim or Gantrisin, where procaine's breakdown product (aminobenzoic acid, or PABA) can blunt how well the antibiotic kills bacteria. The catch is that your medicine, Monopril HCT, is a blood pressure combo: fosinopril (an ACE inhibitor) plus hydrochlorothiazide (a water pill). Even though hydrochlorothiazide has a 'sulfa' part in its chemical structure, it is not a sulfonamide antibiotic, so this PABA antagonism doesn't really apply to it.

On top of that, this concern is only theoretical, based on chemistry rather than real patient reports. I wouldn't expect procaine to weaken your blood pressure control. Still, since procaine products carry their own safety worries, it's smart to run any procaine-containing product by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 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

Procaine Also Interacts With Other Medications

Procaine has 37 major, 18 moderate known drug interactions in our database — the Fosinopril, Hydrochlorothiazide one above is one of them. If you take anything else, check it against the full list below.

Major 37 Moderate 18 No known interaction 2,775 (incl. Fosinopril, Hydrochlorothiazide)
Taking anything else?

Check Another of Your Medications Against Procaine

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

Everything else you take

See Every Supplement That Interacts With Fosinopril, Hydrochlorothiazide

This page covers Procaine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosinopril, Hydrochlorothiazide page lists 238 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: 11 major · 200 moderate · 27 minor.

From our pharmacist’s overview on the Fosinopril, Hydrochlorothiazide page

“Monopril HCT combines two blood pressure medicines, the ACE inhibitor fosinopril and the water pill hydrochlorothiazide, which is why I read its supplement list with genuine wariness rather than a shrug. Eleven of the 238 ingredients on file carry a major rating and deserve your attention first, while most of the 200 rated moderate eit…”

Reviewed by 2 · Jul 18, 2026

Open the Fosinopril, Hydrochlorothiazide interaction page

One more smart check

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

We hold 2 real supplement products containing Procaine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Procaine. Your product may carry other ingredients that interact with Fosinopril, Hydrochlorothiazide too, on top of Procaine — 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 Procaine and Fosinopril, Hydrochlorothiazide 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 Procaine
Top half

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

29 days ago today
Medication Fosinopril, Hydrochlorothiazide
Top 5%

#106 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 Procaine

What is Procaine?

  • Local anesthesia (medical/dental use)
  • Marketed 'anti-aging' supplements
  • General well-being and vitality claims
  • Mood and energy support (unproven)

Procaine is a synthetic local anesthetic (best known by the brand name Novocaine) used by doctors and dentists to numb tissue. It is not a true dietary supplement or herb, and the 'anti-aging' products built around it (such as GH3 or 'Gerovital') have weak evidence and real safety concerns. Talk to your pharmacist or doctor before using any product containing procaine.

Read the full Procaine monograph & all interactions
Keep checking

Other Drugs & Procaine

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

37Major
18Moderate
0Minor
2,774No known interaction
37 Major 18 Moderate 2,774 No interaction
Major

37 interactions

Moderate

18 interactions

No interaction 2,774 drugs checked — show the list

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

Showing the 60 most looked-up of 2,774 medications checked with no known interaction — see the full Procaine list.

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

Can you take Procaine with Fosinopril, Hydrochlorothiazide?
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 Procaine and Fosinopril, Hydrochlorothiazide 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 Fosinopril, Hydrochlorothiazide and Procaine?

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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.