Ibogaine is a psychoactive indole alkaloid derived from plants such as Tabernanthe iboga, characterized by hallucinogenic and oneirogenic effects. Traditionally used by Central African foragers, it has undergone controversial research for the treatment of substance use disorders. Ibogaine exhibits complex pharmacology by interacting with multiple neurotransmitter systems, notably affecting opioid, serotonin, sigma, and NMDA receptors, while its metabolite noribogaine primarily acts as a serotonin reuptake inhibitor and κ-opioid receptor agonist.

The psychoactivity of the root bark of the iboga tree, T. iboga, one of the plants from which ibogaine is extracted, was first discovered by forager tribes in Central Africa, who passed the knowledge to the Bwiti tribe of Gabon. It was first documented in the 19th century for its spiritual use, later isolated and synthesized for its psychoactive properties, briefly marketed in Europe as a stimulant, and ultimately researched—and often controversial—for its potential in treating addiction despite being classified as a controlled substance. Ibogaine can be semisynthetically produced from voacangine, with its total synthesis achieved in 1956 and its structure confirmed by X-ray crystallography in 1960. Ibogaine has been studied for treating substance use disorders, especially opioid addiction, by alleviating withdrawal symptoms and cravings, but its clinical use and development has been limited due to regulatory barriers and serious safety risks like cardiotoxicity. A 2022 systematic review suggested that ibogaine and noribogaine show promise in treating substance use disorders and comorbid depressive symptoms and psychological trauma but carry serious safety risks, necessitating rigorous clinical oversight.

Ibogaine produces a two-phase experience—initially visionary and dream-like with vivid imagery and altered perception, followed by an introspective period marked by lingering side effects like nausea and mood disturbances, which may persist for days. Long-term risks include mania and heart issues such as long QT syndrome, and potential fatal interactions with other drugs.

Ibogaine is federally illegal in the United States, but is used in treatment clinics abroad under legal gray areas, with growing media attention highlighting both its potential and risks in addiction therapy. It has inspired the development of non-hallucinogenic, non-cardiotoxic analogues like 18-MC and tabernanthalog for therapeutic use. In 2025, Texas allocated $50 million for clinical research on ibogaine to develop FDA-approved treatments for opioid use disorder, co-occurring substance use disorders, and other ibogaine-responsive conditions.

Ibogaine is derived from the root of Tabernanthe iboga, a plant known to exhibit [hallucinogenic effects in people who use consume it. It is described as having a typical dose range of 1,000 to 1,500 mg orally, with these doses producing hallucinogenic effects, and a duration of 18 to 36 hours. However, lower doses like 200 to 400 mg orally are also active. In addition, very low doses of ibogaine like 8 to 30 mg orally have been used and reported to produce stimulant effects. The onset of the drug is 1 to 3 hours and peak effects have been described as being reached after 2 hours. With full hallucinogenic doses, ibogaine is described as having three different phases of effects. The first phase is the acute or visionary phase, which onsets after 1 to 3 hours and has a duration of 4 to 8 hours; the second phase is the evaluative or introspective phase, which starts after 4 to 8 hours and has a duration of 8 to 20 hours; and the third phase is residual stimulation, which onsets after 12 to 24 hours and has a duration of 24 to 72 hours or longer. Each of these phases is described as having distinct qualitative effects.

The visionary phase is a dream-like, conscious state called oneirophrenia. Visual effects are almost always present and are often described as films or slideshows. These may be accompanied by increases in long-term recall of visual memory, resulting in autobiographical content. Other changes to sensation and perception may occur, including auditory hallucinations or distortions. Nausea and vomiting can be severe. Subjects may experience extreme confusion and/or a depressed mood. The visionary stage typically lasts 4–8 hours, but may last longer with especially high doses.

The introspective is poorly defined, often simply as 24 or 36 hours post-treatment. Sensation and perception return to normal, but nausea, headaches, and other side effects linger. Insomnia, irritability, and mood changes are often seen, including depression and sometimes mania. Depression can persist well after 36 hours, known as a "grey day"; the effect is well-recognized. A persistently low mood can progress into major depressive disorder, a chronic condition. For the treatment of opioid or alcohol addiction, the subjective experiences do not appear to be important, although they are correlated to some secondary measures (e.g. satisfaction in self-assessments).

Immediate adverse effects of ibogaine ingestion may include nausea, vomiting, tremors leading to ataxia, headaches, and mental confusion. In long-term use, manic episodes may last for several days, possibly including insomnia, irritability, emotional instability, delusions, aggressive behavior, and thoughts of suicide. In the heart, ibogaine causes long QT syndrome at higher doses, apparently by blocking hERG potassium channels and slowing the heart rate. Ibogaine should not be used during pregnancy or breastfeeding.