Drug & supplement interaction

Iboga + Thioridazine

Thioridazine brand name: Mellaril.

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

Thioridazine falls into 3 drug categories that Iboga can interact with; the most serious is rated moderate. Theoretically, iboga may have an additive effect with drugs that prolong the QT interval.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Iboga and Thioridazine

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Iboga interacts with whole categories of medication. Thioridazine falls into 3 of those categories, so it can interact with Iboga in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

QT INTERVAL-PROLONGING DRUGS

1 of 3

Why this applies to Thioridazine

Thioridazine falls under QT INTERVAL-PROLONGING DRUGS — the group Iboga interacts with.

Theoretically, iboga may have an additive effect with drugs that prolong the QT interval.
Numerous case reports suggest that ibogaine, a constituent in iboga, can cause QT interval prolongation.
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 key concern with this combination: thioridazine (Mellaril) is well known for affecting your heart's electrical timing, something we call QT prolongation. In fact, thioridazine carries one of the strongest warnings of any antipsychotic for this very reason. Iboga, through its compound ibogaine, has its own track record of doing the same thing, and there have been case reports linking it to dangerous heart rhythm changes and even deaths.

Stacking two QT-prolonging substances can add up, raising the risk of a serious irregular heartbeat. The evidence for iboga here is anecdotal, but given thioridazine's already significant heart risk, I'd treat this pairing as something to avoid. Please loop in your doctor or pharmacist before combining anything with thioridazine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. O'Connell CW, Gerona RR, Friesen MW, Ly BT. Internet-purchased ibogaine toxicity confirmed with serum, urine, and product content levels. Am J Emerg Med. 2015; 33(7):985.e5-6. PubMed
  2. Vlaanderen L, Martial LC, Franssen EJ, van der Voort PH, Oosterwerff E, Somsen GA. Cardiac arrest after ibogaine ingestion. Clin Toxicol (Phila). 2014;52(6):642-3. PubMed
  3. Asua. Growing menace of ibogaine toxicity. Br J Anaesth. 2013;111(6):1029-30. PubMed
  4. Hoelen DW, Spiering W, Valk GD. Long-QT syndrome induced by the antiaddiction drug ibogaine. N Engl J Med. 2009;360(3):308-9. PubMed
  5. Paling FP, Andrews LM, Valk GD, Blom HJ. Life-threatening complications of ibogaine: three case reports. Neth J Med. 2012;70(9):422-4.
  6. Pleskovic A, Gorjup V, Brvar M, Kozelj G. Ibogaine-associated ventricular tachyarrhythmias. Clin Toxicol (Phila). 2012;50(2):157. PubMed
  7. Litjens RP, Brunt TM. How toxic is ibogaine? Clin Toxicol (Phila). 2016;54(4):297-302. PubMed
  8. Grogan J, Gerona R, Snow JW, Kao L. Ibogaine consumption with seizure-like episodes, QTc-prolongation, and captured cardiac dysrhythmias. J Emerg Med 2019;57(4):e99-e104. PubMed
  9. 105383 Knuijver T, Schellekens A, Belgers M, et al. Safety of ibogaine administration in detoxification of opioid dependent individuals: a descriptive open-label observational study. Addiction 2021. PubMed
  10. Steinberg C, Deyell MW. Cardiac arrest after ibogaine intoxication. J Arrhythm 2018;34(4):455-457. PubMed
Moderate

ANTICHOLINERGIC DRUGS

2 of 3

Thioridazine also falls under ANTICHOLINERGIC DRUGS.

Theoretically, iboga might decrease the effectiveness of anticholinergic drugs.
In vitro research shows that iboga can inhibit acetylcholinesterase and might increase acetylcholine levels. However, the constituent ibogaine does not appear to have this effect.
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. Thioridazine has anticholinergic properties, meaning it tamps down a brain chemical called acetylcholine. Some lab studies suggest Iboga might do the opposite, raising acetylcholine levels, which could in theory work against thioridazine and blunt some of its effects. I want to be honest, though: this is based only on test-tube research, and the main compound in Iboga (ibogaine) did not show this effect. So the real-world concern here is weak and theoretical.

The much bigger issue is safety. Both thioridazine and Iboga can dangerously affect heart rhythm (QT prolongation), and combining them could seriously raise that risk. Ibogaine is illegal in the U.S. and has caused deaths. Please don't combine these, and talk with your doctor or pharmacist before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Alper K, Reith ME, Sershen H. Ibogaine and the inhibition of acetylcholinesterase. J Ethnopharmacol. 2012;139(3):879-82. PubMed
Moderate

CYTOCHROME P450 2D6 (CYP2D6) INHIBITORS

3 of 3

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

Theoretically, taking iboga with CYP2D6 inhibitors might increase the levels and clinical effects of ibogaine.
Ibogaine, the active constituent of iboga, is a substrate of CYP2D6. One pharmacokinetic study shows that taking the CYP2D6 inhibitor paroxetine prior to taking ibogaine 20 mg increases the exposure to ibogaine and its metabolite noribogaine by 2-fold when compared with ibogaine alone.
Severity Moderate Likelihood Possible Evidence B

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 key thing with this pairing: thioridazine is a strong blocker of the liver enzyme CYP2D6, and that same enzyme is what your body uses to break down ibogaine, the active compound in Iboga. So if the two were taken together, the thioridazine would slow ibogaine's clearance and let it pile up. In a small study, a different CYP2D6 blocker doubled ibogaine levels, so this is a real, though not heavily proven, concern.

What worries me most is the heart. Both thioridazine and ibogaine can dangerously lengthen the heart's QT interval, raising the risk of serious, even fatal, rhythm problems. Iboga is also illegal in the US and not something I'd ever recommend. Please talk with your doctor or pharmacist before mixing anything with thioridazine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Henstra M, Wong L, Chahbouni A, et al. Toxicokinetics of ibogaine and noribogaine in a patient with prolonged multiple cardiac arrhythmias after ingestion of internet purchased ibogaine. Clin Toxicol (Phila). 2017;55(6):600-602. PubMed
  2. Glue P, Winter H, Garbe K, et al. Influence of CYP2D6 activity on the pharmacokinetics and pharmacodynamics of a single 20?mg dose of ibogaine in healthy volunteers. J Clin Pharmacol. 2015;55(6):680-7. PubMed
  3. Rodriguez P, Urbanavicius J, Prieto JP, et al. A single administration of the atypical psychedelic ibogaine or its metabolite noribogaine induces an antidepressant-like effect in rats. ACS Chem Neurosci 2020;11(11):1661-1672. 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

Iboga Also Interacts With Other Medications

Iboga has 1 major, 500 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.

Major 1 Moderate 500 No known interaction 2,329 (incl. Thioridazine)
Taking anything else?

Check Another of Your Medications Against Iboga

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

From our Q&A

Questions About Iboga 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 Iboga 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 Iboga 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

How much people look this up

Where Iboga 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 Iboga
Top half

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

29 days ago today
Medication Thioridazine
Steady interest

#2,091 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 Iboga

What is Iboga?

Iboga
  • Drug and alcohol addiction
  • Opioid withdrawal
  • Spiritual and ceremonial rituals
  • Fatigue and stimulant effects
  • Mood and emotional issues

Iboga is a Central African shrub whose root bark contains ibogaine, a powerful hallucinogenic compound studied mainly for addiction. It carries serious safety risks, including dangerous heart rhythm changes and deaths, and ibogaine is illegal in the United States and many other countries. We do not recommend its use outside of tightly controlled research settings.

Read the full Iboga 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 & Iboga

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

1Major
500Moderate
0Minor
2,328No known interaction
1 Major 500 Moderate 2,328 No interaction
Major

1 interaction

Moderate

500 interactions

Showing 60 of 500 moderate interactions — see all 500 on the Iboga page.

No interaction 2,328 drugs checked — show the list

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

Showing the 60 most looked-up of 2,328 medications checked with no known interaction — see the full Iboga list.

See the full Iboga 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
Iboga 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 Iboga and Thioridazine Together: Common Questions

Can you take Iboga 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 3 interactions listed for Iboga and Thioridazine?
Thioridazine belongs to more than one drug category, and Iboga 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 Iboga 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 Iboga?

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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.