Drug & supplement interaction

Rice Protein + Fosinopril, Hydrochlorothiazide

Fosinopril, Hydrochlorothiazide brand name: Monopril HCT.

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

Rice Protein has a moderate interaction with Fosinopril, Hydrochlorothiazide. In laboratory research, hydrolyzed rice protein inhibits angiotensin-converting enzyme (ACE).

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

Rice Protein and Fosinopril, Hydrochlorothiazide

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

Moderate

ACE INHIBITORS (ACEIs)

Why this applies to Fosinopril, Hydrochlorothiazide

Fosinopril, Hydrochlorothiazide falls under ACE INHIBITORS (ACEIs) — the group Rice Protein interacts with.

In laboratory research, hydrolyzed rice protein inhibits angiotensin-converting enzyme (ACE). In animal research, the inhibition of ACE is correlated with a reduction in systolic blood pressure. So far, this effect has not been shown in humans. Theoretically, concomitant use of rice protein and ACE inhibitors may increase the risk of blood pressure becoming too low. Use with caution. ACE inhibitors include benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik).
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

Here's the gist for your Monopril HCT, which pairs fosinopril (a blood pressure medicine in the ACE inhibitor family) with hydrochlorothiazide (a water pill). In lab studies, a special hydrolyzed form of rice protein seemed to block the same ACE enzyme that fosinopril blocks. In animals, that lined up with lower blood pressure. The thinking is that stacking the two could, in theory, push your pressure down a little too far.

I want to be straight with you, though: this has only been seen in test tubes and animals, not in people, so I wouldn't lose sleep over it. A normal scoop of rice protein in a shake is very different from concentrated lab extracts. Still, if you notice dizziness, lightheadedness when standing, or feeling unusually tired, mention it to your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li GH, Qu MR, Wan JZ, You JM. Antihypertensive effect of rice protein hydrolysate with in vitro angiotensin I-converting enzyme inhibitory activity in spontaneously hypertensive rats. Asia Pac J Clin Nutr. 2007;16 Suppl 1:275-80.

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

Rice Protein Also Interacts With Other Medications

Rice Protein has 22 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.

Moderate 22 No known interaction 2,808 (incl. Fosinopril, Hydrochlorothiazide)
Taking anything else?

Check Another of Your Medications Against Rice Protein

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

Everything else you take

See Every Supplement That Interacts With Fosinopril, Hydrochlorothiazide

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

We hold 610 real supplement products containing Rice Protein, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Rice Protein. Your product may carry other ingredients that interact with Fosinopril, Hydrochlorothiazide too, on top of Rice Protein — 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 Rice Protein 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 Rice Protein
Top 25%

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

29 days ago today
Medication Fosinopril, Hydrochlorothiazide
Top 5%

#94 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 Rice Protein

What is Rice Protein?

  • Building and maintaining muscle
  • Post-workout recovery
  • Plant-based protein source
  • Meal replacement and shakes
  • Weight management support

Rice protein is a plant-based protein powder made from rice that offers an easy way to add protein to your diet, especially if you avoid dairy or animal products. It is generally considered safe and well tolerated, though on its own it is lower in the amino acid lysine and is often blended with pea protein for a more complete amino acid profile. Talk to your pharmacist or doctor before using it if you have kidney problems or other health conditions.

Read the full Rice Protein monograph & all interactions
Keep checking

Other Drugs & Rice Protein

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

0Major
22Moderate
0Minor
2,807No known interaction
22 Moderate 2,807 No interaction
Moderate

22 interactions

No interaction 2,807 drugs checked — show the list

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

Showing the 60 most looked-up of 2,807 medications checked with no known interaction — see the full Rice Protein list.

See the full Rice Protein 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
Rice Protein 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 Rice Protein and Fosinopril, Hydrochlorothiazide Together: Common Questions

Can you take Rice Protein 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 Rice Protein 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 Rice Protein?

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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.