Drug & supplement interaction

English Ivy + Thioridazine

Thioridazine brand name: Mellaril.

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

Thioridazine falls into 2 drug categories that English Ivy can interact with; the most serious is rated moderate. Theoretically, English ivy might increase the levels of drugs metabolized by CYP2C19.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

English Ivy and Thioridazine

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

English Ivy interacts with whole categories of medication. Thioridazine falls into 2 of those categories, so it can interact with English Ivy in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 2

Why this applies to Thioridazine

Thioridazine falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group English Ivy interacts with.

Theoretically, English ivy might increase the levels of drugs metabolized by CYP2C19.
In vitro research shows that English ivy inhibits CYP2C19 enzymes. So far, this interaction has not been reported in humans.
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 idea behind this pairing. Your body uses an enzyme called CYP2C19 to help break down thioridazine (Mellaril). English ivy, in lab tests, appears to slow that enzyme down. If it did the same thing in people, less thioridazine would get cleared, so the drug could build up and you might feel its effects and side effects more strongly. With this medicine that can mean extra drowsiness, dizziness, a dry mouth, or low blood pressure when you stand up.

My honest take: this is only a theoretical concern from test-tube studies, and it hasn't actually been seen in real patients. Still, thioridazine is a serious medicine with known heart-rhythm risks, so I'd play it safe. Please check with your pharmacist or doctor before combining the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rehman SU, Kim IS, Choi MS, Kim SH, Zhang Y, Yoo HH. Time-dependent Inhibition of CYP2C8 and CYP2C19 by Hedera helix Extracts, A Traditional Respiratory Herbal Medicine. Molecules. 2017;22(7). PubMed
Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 2

Thioridazine also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, English ivy might increase the levels of drugs metabolized by CYP2D6.
In vitro research shows that English ivy inhibits CYP2D6 enzymes. So far, this interaction has not been reported in humans.
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 gist: your body relies on a liver enzyme called CYP2D6 to break down thioridazine. In lab studies, English ivy appears to slow that enzyme down. If that held true in people, thioridazine could clear more slowly and build up in your system, which can mean stronger effects and more side effects like drowsiness, dizziness, dry mouth, or a faster heartbeat.

The part that matters most with thioridazine is its known effect on heart rhythm (a QT prolongation risk). Higher levels could make that worse, so I'd be cautious here. That said, this is theoretical, based only on test-tube data and never reported in real patients. Please don't stop or change anything on your own. Just run the ivy cough product by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rehman SU, Kim IS, Choi MS, Kim SH, Zhang Y, Yoo HH. Time-dependent Inhibition of CYP2C8 and CYP2C19 by Hedera helix Extracts, A Traditional Respiratory Herbal Medicine. Molecules. 2017;22(7). PubMed

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

English Ivy Also Interacts With Other Medications

English Ivy has 279 moderate known drug interactions in our database — the Thioridazine one above is among them. If you take anything else, check it against the full list below.

Moderate 279 No known interaction 2,551 (incl. Thioridazine)
Taking anything else?

Check Another of Your Medications Against English Ivy

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

From our Q&A

Questions About English Ivy or Thioridazine

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

This page covers English Ivy only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Thioridazine page lists 168 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 11 major · 125 moderate · 32 minor.

From our pharmacist’s overview on the Thioridazine page

“Thioridazine (Mellaril) is an older antipsychotic already known for disturbing the heart's rhythm, and the supplements that worry me most here do the same thing, stretching the QT interval further. Grapefruit in large amounts sits in that group, alongside ephedra and several other major-rated entries.”

Reviewed by 2 · Jul 18, 2026

Open the Thioridazine interaction page

One more smart check

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

We hold 118 real supplement products containing English Ivy, each one broken down to its full ingredient list — and combination products often carry several ingredients besides English Ivy. Your product may carry other ingredients that interact with Thioridazine too, on top of English Ivy — 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 English Ivy and Thioridazine 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 English Ivy
Steady interest

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

29 days ago today
Medication Thioridazine
Steady interest

#2,445 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 English Ivy

What is English Ivy?

English Ivy
  • Cough and chest congestion
  • Bronchitis
  • Asthma symptoms
  • Sore throat
  • Skin irritation

English ivy leaf extract is most commonly used in cough and cold syrups to help loosen mucus and ease coughing, and it is a popular ingredient in many European herbal products. Some research suggests it may help with certain coughs, but the evidence is still limited and mixed. The raw plant is poisonous if eaten and can irritate skin, so only use properly prepared commercial products and check with your pharmacist first.

Read the full English Ivy monograph & all interactions
Medication

About Thioridazine

What Is Thioridazine Used For?

Brand name: Mellaril

Thioridazine Hydrochloride tablets are used for the management of schizophrenia — but only in patients who have already tried at least two other antipsychotic medications without adequate results, either because those drugs didn't work well enough or caused intolerable side effects.

Because thioridazine carries serious heart-rhythm risks, it is considered a last-resort option for schizophrenia, not a first-line treatment. It is not approved for dementia-related psychosis or any other psychiatric condition.

See full Thioridazine drug information
Keep checking

Other Drugs & English Ivy

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

0Major
279Moderate
0Minor
2,550No known interaction
279 Moderate 2,550 No interaction
Moderate

279 interactions

Showing 60 of 279 moderate interactions — see all 279 on the English Ivy page.

No interaction 2,550 drugs checked — show the list

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

Showing the 60 most looked-up of 2,550 medications checked with no known interaction — see the full English Ivy list.

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

Can you take English Ivy with Thioridazine?
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.
Why are there 2 interactions listed for English Ivy and Thioridazine?
Thioridazine belongs to more than one drug category, and English Ivy interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the English Ivy and Thioridazine 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 Thioridazine and English Ivy?

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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.