Drug & supplement interaction

Strophanthus + Phenolphthalein

Phenolphthalein brand names: Modane, Evac-Q-Tab, Modane Mild.

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

Strophanthus has a moderate interaction with Phenolphthalein. Overuse or misuse of laxatives may cause electrolyte depletion and increase risk of strophanthus toxicity.

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

Strophanthus and Phenolphthalein

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

Moderate

STIMULANT LAXATIVES

Why this applies to Phenolphthalein

Phenolphthalein falls under STIMULANT LAXATIVES — the group Strophanthus interacts with.

Overuse or misuse of laxatives may cause electrolyte depletion and increase risk of strophanthus toxicity.
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 to keep in mind. Phenolphthalein is an old-fashioned stimulant laxative that gets your bowels moving. When laxatives like this are used too often or for too long, your body can lose important minerals, especially potassium, through frequent loose stools. That mineral loss is where the real concern comes in.

Strophanthus works much like digoxin, and these heart-affecting compounds become more dangerous when your potassium runs low. So combining the two could raise the risk of Strophanthus toxicity, things like an irregular or dangerously slow heartbeat, nausea, or weakness. To be clear, this is a theoretical caution based on how the two work, not a heavily documented event. Strophanthus already requires close medical supervision, so please loop in your doctor or pharmacist before mixing these.

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 Phenolphthalein 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. Phenolphthalein)
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 Phenolphthalein

This page covers Strophanthus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenolphthalein page lists 46 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Jalap (major), Oleander (major), Alder Buckthorn (moderate) and Aloe (moderate).

By severity: 3 major · 34 moderate · 9 minor.

From our pharmacist’s overview on the Phenolphthalein page

“Phenolphthalein is a stimulant laxative itself, and that is the heart of the problem with these combinations. Most of the herbs on file, jalap being one, act the same way, so pairing them can drain fluid and potassium quickly.”

Reviewed by 2 · Jul 18, 2026

Open the Phenolphthalein interaction page

How much people look this up

Where Strophanthus and Phenolphthalein 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 Phenolphthalein
Top half

#1,101 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 Phenolphthalein, 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 Phenolphthalein supplement interactions › Every supplement checked against Phenolphthalein, 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 Phenolphthalein Together: Common Questions

Can you take Strophanthus with Phenolphthalein?
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 Phenolphthalein 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 Phenolphthalein and Strophanthus?

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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.