Drug & supplement interaction

Strophanthus + Cyclothiazide

Cyclothiazide brand names: Fluidil, Anhydron.

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

Strophanthus has a moderate interaction with Cyclothiazide. Theoretically, concomitant use of potassium-depleting diuretics and strophanthus can increase the risk of cardiac glycoside toxicity due to potassium depletion.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Strophanthus and Cyclothiazide

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

Moderate

DIURETIC DRUGS

Why this applies to Cyclothiazide

Cyclothiazide falls under DIURETIC DRUGS — the group Strophanthus interacts with.

Theoretically, concomitant use of potassium-depleting diuretics and strophanthus can increase the risk of cardiac glycoside toxicity due to potassium depletion. Some diuretics that can deplete potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide), and others.
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 concern with pairing these two. Cyclothiazide is a thiazide-type water pill, and like its cousins (hydrochlorothiazide, chlorthalidone), it tends to flush potassium out of your body over time. Strophanthus, meanwhile, contains heart-acting compounds (cardiac glycosides like ouabain) that behave a lot like digoxin. When potassium runs low, the heart becomes more sensitive to these glycosides, which raises the risk of toxicity.

In real life that could show up as nausea, dizziness, vision changes, or an irregular or unusually slow heartbeat. I'll be honest: this warning is theoretical, based on how the two work rather than strong human studies. Still, Strophanthus is potent and not a casual supplement. Please don't combine these without your doctor or pharmacist guiding you and checking your potassium first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 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

Strophanthus Also Interacts With Other Medications

Strophanthus has 3 major, 119 moderate known drug interactions in our database — the Cyclothiazide one above is one of them. If you take anything else, check it against the full list below.

Major 3 Moderate 119 No known interaction 2,708 (incl. Cyclothiazide)
Taking anything else?

Check Another of Your Medications Against Strophanthus

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

Everything else you take

See Every Supplement That Interacts With Cyclothiazide

This page covers Strophanthus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Cyclothiazide page lists 210 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 · 175 moderate · 25 minor.

From our pharmacist’s overview on the Cyclothiazide page

“Cyclothiazide (Fluidil, Anhydron) is a thiazide diuretic for high blood pressure and fluid retention, and its 210 supplement interactions warrant real vigilance, especially the ten rated major. Most entries pull in one of two directions.”

Reviewed by 2 · Jul 18, 2026

Open the Cyclothiazide interaction page

How much people look this up

Where Strophanthus and Cyclothiazide 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 Strophanthus
Top half

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

29 days ago today
Medication Cyclothiazide
Top half

#1,252 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 Strophanthus

What is Strophanthus?

  • Heart failure
  • Angina (chest pain)
  • Irregular heartbeat
  • Circulation support
  • Traditional African arrow poison (historical)

Strophanthus is a plant that contains powerful heart-affecting compounds called cardiac glycosides (the best known is ouabain/g-strophanthin). Because these substances can strongly affect heart rhythm and are toxic in the wrong amount, Strophanthus is not a casual supplement and should never be used without close medical supervision. Reliable modern evidence for its supplement use is limited.

Read the full Strophanthus monograph & all interactions
Keep checking

Other Drugs & Strophanthus

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

3Major
119Moderate
0Minor
2,707No known interaction
3 Major 119 Moderate 2,707 No interaction
Major

3 interactions

Moderate

119 interactions

Showing 60 of 119 moderate interactions — see all 119 on the Strophanthus page.

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Strophanthus list.

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

Can you take Strophanthus with Cyclothiazide?
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 Strophanthus and Cyclothiazide 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 Cyclothiazide and Strophanthus?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.