Ibogaine Drug Interactions

Almost every interaction list circulating on this subject is a single undifferentiated column of drug names. That is not usable, because the two mechanisms behave differently, need different precautions, and have very different consequences when ignored.

Mechanism one: the enzyme

Ibogaine is converted to noribogaine by a single liver enzyme, CYP2D6. In human liver preparations the high-affinity component of that reaction accounts for more than 95 per cent of total clearance. One enzyme does essentially all the work.

That enzyme’s activity varies enormously between people on genetic grounds. In fourteen genotyped patients given a single dose, clearance was 0.82 litres per hour at an activity score of zero and rose by about 30.7 litres per hour for each point of score, a span of roughly thirty-seven fold.

Anything that inhibits that enzyme therefore acts like a dose increase.

The best direct evidence is a study of 21 healthy volunteers pretreated for six days with paroxetine or placebo. Exposure to ibogaine and its metabolite was about twice as high after paroxetine. The authors recommend genotyping, and at least halving the intended dose in poor metabolisers.

Two caveats keep that honest. The dose studied was 20 mg, a small fraction of a treatment dose. And there was no cardiac endpoint, so it establishes that a common antidepressant doubles exposure, not what doubled exposure does to a heart.

Which drugs inhibit it

From the drugs’ own approved labels, not from a secondary list.

Three that are not this problem

Worth stating plainly, because they are commonly assumed to be.

Lamotrigine is cleared predominantly by glucuronidation, and its label records that it does not reduce the clearance of drugs eliminated by CYP2D6. Valproate is metabolised almost entirely by other routes, with cytochrome oxidation a minor secondary pathway. Carbamazepine is a potent inducer of several enzymes, and its label mentions CYP2D6 zero times.

On carbamazepine specifically: the concern people raise is that it would speed ibogaine’s clearance. No published source establishes any pharmacokinetic interaction between carbamazepine and ibogaine, and the regulator’s own table lists no CYP2D6 inducers at all. We say so rather than repeating the claim.

Mechanism two: the heart

This is the one that kills, and it is entirely separate from the enzyme.

Ibogaine blocks a cardiac potassium channel and lengthens the QT interval, the period during which the heart’s electrical system recovers between beats. In the same fourteen patients, QT prolongation tracked ibogaine concentration and not noribogaine, which did not correlate at all.

Any drug that lengthens that interval adds to the effect. From the labels:

Citalopram carries the most explicit warnings of the group. Dose-dependent QTc prolongation, torsades de pointes, ventricular tachycardia and sudden death have occurred; avoid in congenital long QT syndrome, bradycardia, low potassium or magnesium, and in patients taking other drugs that prolong the QTc interval; discontinue if QTc persists above 500 milliseconds.

Haloperidol carries the sentence that transfers most directly: avoid concomitant use with drugs that may increase the risk of QTc prolongation, and cases have been reported even in the absence of predisposing factors.

Ziprasidone is described in its own label as having a greater capacity to prolong the interval than several other antipsychotics.

Escitalopram, by contrast, carries QT prolongation only as a post-marketing adverse reaction with no equivalent dose-dependent guidance, and quetiapine has a conditional profile: not associated with a persistent increase in trials, but never systematically evaluated in a dedicated study.

Methadone deserves its own paragraph

Because of who seeks ibogaine, this is the most consequential combination on the page.

A meta-analysis of 22 observational studies found a pooled prevalence of QT prolongation of 34 per cent among people on methadone maintenance, with pooled torsades at 2 per cent. An earlier study of 167 methadone patients against 80 controls found a QTc of 500 milliseconds or more in 16.2 per cent against zero, and torsades in 3.6 per cent.

So a substantial share of the people most likely to consider ibogaine already have a lengthened QT interval before they take anything. Nobody has studied the combination.

Lithium is neither, and still a problem

Lithium is not metabolised by any cytochrome enzyme; the word does not appear in its label. At therapeutic levels it shows no QT signal.

At toxic levels it does. In a cohort with 112 intoxication episodes, QT prolongation occurred in 24 per cent, and in 54 per cent of those the QTc exceeded 500 milliseconds.

Alcohol

This is the most searched question on this page and it has the least evidence behind it, so here is exactly what is and is not known.

No published study measures ibogaine and alcohol together in humans. Nobody can give you an interaction magnitude, because nobody has produced one.

What is documented sits either side of that gap. Chronic alcohol use depletes magnesium and potassium, and both losses lengthen the QT interval, which is the same direction ibogaine pushes. Heavy drinking damages the liver, and the liver is where the only enzyme that clears ibogaine lives.

And alcohol withdrawal is dangerous in its own right, unlike opioid withdrawal: severe withdrawal can kill through seizures and delirium, and requires medical management. A person who stops drinking in order to travel for treatment may be in withdrawal at the moment of dosing, and vomiting during treatment removes the electrolytes that withdrawal has already lowered.

Ibogaine for alcoholism sets out how little evidence supports the treatment itself.

How to use this page

The useful move is not to memorise a list. It is to take everything you take, including things people forget are drugs, and ask two questions of each.

Does it inhibit CYP2D6? If so it acts as a dose increase, and for paroxetine and bupropion it keeps doing so after you stop. If the drug in question is an antidepressant, coming off antidepressants covers the washout that clinics require.

Does it prolong the QT interval? If so it adds to the mechanism that has killed people, and that addition is not gradual in its consequences.

A drug that does neither has had its two known interaction routes removed. It has not been shown safe, because no drug has, and the review that recommends genotyping also recommends that treatment happen only under controlled medical supervision with rigorous monitoring.

Ibogaine and the heart covers the mechanism itself, and who should never take ibogaine covers the conditions rather than the drugs.