Drug & supplement interaction

Reishi Mushroom + Hydrochlorothiazide

Hydrochlorothiazide brand names: Esidrix, Hydro, Microzide, HydroDiuril, Hydro-D, and others.

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

Reishi Mushroom has a moderate interaction with Hydrochlorothiazide. Theoretically, concurrent use of reishi mushroom with antihypertensive drugs might increase the risk of hypotension.

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

Reishi Mushroom and Hydrochlorothiazide

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Hydrochlorothiazide

Hydrochlorothiazide falls under ANTIHYPERTENSIVE DRUGS — the group Reishi Mushroom interacts with.

Theoretically, concurrent use of reishi mushroom with antihypertensive drugs might increase the risk of hypotension.
Reishi mushroom has shown hypotensive activity in animal research. Clinical evidence suggests that reishi mushroom reduces blood pressure in some, but not all, patients with hypertension.
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 simple version: your hydrochlorothiazide (Microzide) is a water pill that already nudges your blood pressure down. Reishi mushroom may have a mild blood-pressure-lowering effect of its own. Put the two together and, in theory, your blood pressure could dip a little lower than expected.

If that happens, you might feel lightheaded, dizzy, or faint, especially when you stand up quickly. I want to be honest about the evidence though, this concern comes mostly from animal and lab studies, not solid human research, so it may not amount to much for most people. Still, it's worth a quick chat with your pharmacist or doctor before starting reishi, and keep an eye on your blood pressure readings at home.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lee SY, Rhee HM. Cardiovascular effects of mycelium extract of Ganoderma lucidum: inhibition of sympathetic outflow as a mechanism of its hypotensive action. Chem Pharm Bull (Tokyo) 1990;38:1359-64. PubMed
  2. Kabir, Y., Kimura, S., and Tamura, T. Dietary effect of Ganoderma lucidum mushroom on blood pressure and lipid levels in spontaneously hypertensive rats (SHR). J Nutr Sci Vitaminol.(Tokyo) 1988;34(4):433-438. PubMed
  3. Kanmatsuse, K., Kajiwara, N., Hayashi, K., Shimogaichi, S., Fukinbara, I., Ishikawa, H., and Tamura, T. [Studies on Ganoderma lucidum. I. Efficacy against hypertension and side effects]. Yakugaku Zasshi 1985;105(10):942-947. PubMed
  4. Jin H, Zhang G, Cao X, and et al. Treatment of hypertension by linzhi combined with hypotensor and its effects on arterial, arteriolar and capillary pressure and microcirculation. In: Niimi H, Xiu RJ, Sawada T, and et al. Microcirculatory Approach to Asi

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

Reishi Mushroom Also Interacts With Other Medications

Reishi Mushroom has 374 moderate known drug interactions in our database — the Hydrochlorothiazide one above is one of them. If you take anything else, check it against the full list below.

Moderate 374 No known interaction 2,456 (incl. Hydrochlorothiazide)
Taking anything else?

Check Another of Your Medications Against Reishi Mushroom

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

From our Q&A

Questions About Reishi Mushroom or Hydrochlorothiazide

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

This page covers Reishi Mushroom only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydrochlorothiazide page lists 230 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 · 195 moderate · 25 minor.

From our pharmacist’s overview on the Hydrochlorothiazide page

“Hydrochlorothiazide sits at the strong end of the caution scale for supplement interactions, and the small group of major-rated entries deserves a careful read before everything else on the page. Most of what appears here either adds to the pill's blood-pressure-lowering effect or piles onto its diuretic action, pushing fluid and potas…”

Reviewed by 2 · Jul 18, 2026

Open the Hydrochlorothiazide interaction page

How much people look this up

Where Reishi Mushroom and 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 Reishi Mushroom
Top 10%

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

29 days ago today
Medication Hydrochlorothiazide
Top 10%

#150 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 Reishi Mushroom

What is Reishi Mushroom?

Reishi Mushroom
  • Immune support
  • Fatigue and general well-being
  • Stress and sleep
  • Inflammation
  • Heart and cholesterol health

Reishi is a traditional Asian mushroom widely used to support the immune system and overall wellness. Human evidence for most of its claimed benefits is limited or low-quality, so it should not replace proven treatments. It is generally well tolerated for short-term use, but check with your pharmacist or doctor before starting, especially if you are pregnant, nursing, or take other medicines.

Read the full Reishi Mushroom monograph & all interactions
Medication

About Hydrochlorothiazide

What Is Hydrochlorothiazide Used For?

Brand names: Esidrix, Hydro, Microzide, HydroDiuril, Hydro-D, Oretic, Aquazide H, Aquazide, HCTZ

Hydrochlorothiazide treats high blood pressure (hypertension) in adults and children, either alone or combined with other blood pressure medicines. Lowering blood pressure reduces the risk of strokes and heart attacks. The capsule form is indicated specifically for hypertension management.

It also treats edema (fluid buildup) associated with congestive heart failure, liver cirrhosis, and kidney diseases including nephrotic syndrome. The tablet form is additionally indicated for edema caused by corticosteroid and estrogen therapy, as well as conditions such as acute glomerulonephritis and chronic renal failure. Inzirqo (the oral suspension) is indicated for both hypertension and edema in adult and pediatric patients.

See full Hydrochlorothiazide drug information
Keep checking

Other Drugs & Reishi Mushroom

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

0Major
374Moderate
0Minor
2,455No known interaction
374 Moderate 2,455 No interaction
Moderate

374 interactions

Showing 60 of 374 moderate interactions — see all 374 on the Reishi Mushroom page.

No interaction 2,455 drugs checked — show the list

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

Showing the 60 most looked-up of 2,455 medications checked with no known interaction — see the full Reishi Mushroom list.

See the full Reishi Mushroom interactions page
See every supplement checked against 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
Reishi Mushroom monograph › Uses, safety, and every drug interaction in one place Hydrochlorothiazide supplement interactions › Every supplement checked against Hydrochlorothiazide, ranked by severity Hydrochlorothiazide 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 Reishi Mushroom and Hydrochlorothiazide Together: Common Questions

Can you take Reishi Mushroom with 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 Reishi Mushroom and 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 Hydrochlorothiazide and Reishi Mushroom?

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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.