Drug & supplement interaction

Rehmannia + Losartan Potassium

Losartan Potassium brand name: Cozaar.

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

Rehmannia has a moderate interaction with Losartan Potassium. Theoretically, rehmannia might increase the risk of hypotension when taken with antihypertensive drugs.

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

Rehmannia and Losartan Potassium

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Losartan Potassium

Losartan Potassium falls under ANTIHYPERTENSIVE DRUGS — the group Rehmannia interacts with.

Theoretically, rehmannia might increase the risk of hypotension when taken with antihypertensive drugs.
Animal research shows that rehmannia may have hypotensive effects. Laboratory research shows that formulations of dried and processed rehmannia root inhibit angiotensin-converting enzyme (ACE).
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

Losartan (Cozaar) is a blood pressure medicine, and Rehmannia may also gently lower blood pressure on its own. In animal and lab studies, this root showed mild blood-pressure-lowering activity and even blocked an enzyme involved in blood pressure control. So when you stack it on top of losartan, the worry is that your pressure could drop a bit too far.

If that happened, you might feel dizzy, lightheaded, tired, or wobbly when standing up quickly. I want to be honest though: this is mostly theoretical and comes from lab and animal work, not from people, so the real-world risk is uncertain. If you take losartan and want to try Rehmannia, check with your pharmacist or doctor first, and keep an eye on your blood pressure readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chao CH, Hsu JL, Chen MF, et al. Anti-hypertensive effects of Radix Rehmanniae and its active ingredients. Nat Prod Res. 2020;34(11):1547-1552.

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

Rehmannia Also Interacts With Other Medications

Rehmannia has 257 moderate known drug interactions in our database — the Losartan Potassium one above is one of them. If you take anything else, check it against the full list below.

Moderate 257 No known interaction 2,573 (incl. Losartan Potassium)
Taking anything else?

Check Another of Your Medications Against Rehmannia

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

From our Q&A

Questions About Rehmannia or Losartan Potassium

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

This page covers Rehmannia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Losartan Potassium page lists 253 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), Grapefruit (major) and St. John's Wort (major).

By severity: 6 major · 205 moderate · 42 minor.

From our pharmacist’s overview on the Losartan Potassium page

“Losartan potassium (Cozaar) treats high blood pressure, and this is a list to respect, because six of its 253 supplement interactions carry a major rating. Most entries do one of two things.”

Reviewed by 2 · Jul 18, 2026

Open the Losartan Potassium interaction page

One more smart check

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

We hold 861 real supplement products containing Rehmannia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Rehmannia. Your product may carry other ingredients that interact with Losartan Potassium too, on top of Rehmannia — 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 Rehmannia and Losartan Potassium 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 Rehmannia
Top 25%

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

29 days ago today
Medication Losartan Potassium
Top 10

#8 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 Rehmannia

What is Rehmannia?

  • Kidney and adrenal support
  • Anemia and blood building (traditional)
  • Inflammatory conditions
  • Allergies
  • Fatigue and aging-related complaints

Rehmannia is a root used for centuries in Traditional Chinese Medicine, often to 'tonify' the kidneys and support energy or blood health. Human evidence for most modern uses is limited, so it should be viewed as unproven rather than reliable. Talk with a pharmacist or doctor before trying it, especially if you are pregnant, breastfeeding, or take other medicines.

Read the full Rehmannia monograph & all interactions
Medication

About Losartan

What Is Losartan Used For?

Brand name: Cozaar

Losartan tablets — available as branded Cozaar and several generic products — are used to treat high blood pressure (hypertension) in adults and children 6 years and older. Lowering blood pressure reduces the risk of strokes and heart attacks. Losartan tablets are also used to reduce the risk of stroke in people with high blood pressure who also have left ventricular hypertrophy (an enlarged left side of the heart). Note: evidence suggests this stroke-risk benefit may not apply to Black patients.

Losartan tablets are additionally approved to protect the kidneys in people with type 2 diabetes, high blood pressure, and signs of kidney damage (diabetic nephropathy). Arbli, the oral suspension form, shares these same approved uses.

See full Losartan drug information
Keep checking

Other Drugs & Rehmannia

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

0Major
257Moderate
0Minor
2,572No known interaction
257 Moderate 2,572 No interaction
Moderate

257 interactions

Showing 60 of 257 moderate interactions — see all 257 on the Rehmannia page.

No interaction 2,572 drugs checked — show the list

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

Showing the 60 most looked-up of 2,572 medications checked with no known interaction — see the full Rehmannia list.

See the full Rehmannia interactions page
See every supplement checked against Losartan Potassium, 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
Rehmannia monograph › Uses, safety, and every drug interaction in one place Losartan Potassium supplement interactions › Every supplement checked against Losartan Potassium, ranked by severity Losartan drug information › The full plain-English guide to this medication 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 Rehmannia and Losartan Potassium Together: Common Questions

Can you take Rehmannia with Losartan Potassium?
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 Rehmannia and Losartan Potassium 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 Losartan Potassium and Rehmannia?

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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.