Drug & supplement interaction

Lily-of-the-valley + Cyclothiazide

Cyclothiazide brand names: Fluidil, Anhydron.

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

Lily-of-the-valley has a moderate interaction with Cyclothiazide. Theoretically, using lily-of-the-valley with diuretics can increase the risk of cardiac glycoside toxicity.

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

Lily-of-the-valley 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 Lily-of-the-valley interacts with.

Theoretically, using lily-of-the-valley with diuretics can increase the risk of cardiac glycoside toxicity.
Lily-of-the-valley contains cardiac glycosides. Concomitant use of potassium depleting diuretics and lily-of-the-valley can increase the risk of cardiac glycoside toxicity due to potassium depletion and electrolyte imbalance.
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 connection worth knowing. Cyclothiazide is a thiazide-type water pill, and like other diuretics in its family, it can flush potassium out of your body over time. That matters here because lily-of-the-valley contains natural heart compounds (cardiac glycosides) that act a lot like digoxin. When your potassium runs low, your heart becomes more sensitive to those glycoside effects, which can tip you into toxicity.

In real terms, that could mean an irregular or slowed heartbeat, nausea, dizziness, or confusion. I'll be honest, this is a theoretical concern based on how these things work, not something proven in studies, and lily-of-the-valley is poisonous and shouldn't be used to self-treat anyway. Please don't change your cyclothiazide on your own, just check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Burnham TH, ed. Drug Facts and Comparisons, Updated Monthly. Facts and Comparisons, St. Louis, MO.

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

Lily-of-the-valley Also Interacts With Other Medications

Lily-of-the-valley has 26 major, 130 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 26 Moderate 130 No known interaction 2,674 (incl. Cyclothiazide)
Taking anything else?

Check Another of Your Medications Against Lily-of-the-valley

Covers the 2,830 medications we’ve checked against Lily-of-the-valley. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Cyclothiazide

This page covers Lily-of-the-valley 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

One more smart check

Taking Lily-of-the-valley as Part of a Dietary Supplement Product? Check It for Interactions

We hold 10 real supplement products containing Lily-of-the-valley, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lily-of-the-valley. Your product may carry other ingredients that interact with Cyclothiazide too, on top of Lily-of-the-valley — 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 Lily-of-the-valley 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 Lily-of-the-valley
Steady interest

#1,192 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Cyclothiazide
Top half

#1,031 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 Lily-of-the-valley

What is Lily-of-the-valley?

Lily-of-the-valley
  • Heart failure (historical)
  • Irregular heartbeat (historical)
  • Fluid retention/edema
  • General heart tonic (traditional)

Lily-of-the-valley is a poisonous plant that contains powerful heart-affecting compounds called cardiac glycosides, similar to the drug digoxin. While it was used historically for heart conditions, it is dangerous and is not recommended for self-treatment. All parts of the plant are toxic, and accidental poisoning can be life-threatening.

Read the full Lily-of-the-valley monograph & all interactions
Keep checking

Other Drugs & Lily-of-the-valley

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

26Major
130Moderate
0Minor
2,673No known interaction
26 Major 130 Moderate 2,673 No interaction
Major

26 interactions

Moderate

130 interactions

Showing 60 of 130 moderate interactions — see all 130 on the Lily-of-the-valley page.

No interaction 2,673 drugs checked — show the list

We also checked Lily-of-the-valley against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,673 medications checked with no known interaction — see the full Lily-of-the-valley list.

See the full Lily-of-the-valley 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
Lily-of-the-valley 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 Lily-of-the-valley and Cyclothiazide Together: Common Questions

Can you take Lily-of-the-valley 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 Lily-of-the-valley 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 Lily-of-the-valley?

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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.