Bufotenine is a hallucinogenic serotonin analog found in frog or toad skins, mushrooms, higher plants, and mammals (especially in the brains, plasma, and urine of schizophrenics). Bufotenine has been used as a tool in CNS studies and misused as a psychedelic.

Bufotenine:
https://drugs.ncats.io/drug/0A31347TZK

Bufotenin is a naturally occurring psychedelic drug. It is found in a wide array of flora and fauna, including several species of psychoactive toads, most notably the Colorado River toad. The overall effects of bufotenin are generally described as less pleasant than those of other psychedelics such as LSD.

The Colorado River toad (Incilius alvarius), also known as the Sonoran Desert toad, is a psychoactive toad found in northern Mexico and the southwestern United States. Its skin and venom contain 5-MeO-DMT and bufotenin. The toad's primary defense system are glands that produce a poison that may be potent enough to kill a grown dog. These parotoid glands also produce the 5-MeO-DMT and bufotenin for which the toad is known.

Bufotenin is not habit-forming and the desire to use it can actually decrease with use. It is most often self-regulating. Tolerance to the effects of bufotenin are built almost immediately after ingestion. After that, it takes about 1 hour for the tolerance to be reduced to half and 2 hours to be back at baseline (in the absence of further consumption).

Although many psychoactive substances are safe to use on their own, they can quickly become dangerous or even life-threatening when combined with other substances.

Excerpt from psychonautwiki.org:
https://psychonautwiki.org/wiki/Bufotenin

In the United States, another toad species, Bufo alvarius, known as the Colorado River toad or the Sonoran Desert toad, causes similar effects. Although it isn't illegal to own a Colorado River toad in the United States, the active chemical in toad venom, bufotenine, is a controlled substance. This is the same chemical contained in cane toad venom. Bufotenine related drug arrests reappeared in Southwestern states such as Arizona in the mid 1980s and '90s, following its original heyday in the 1960s.

People looking to get high obtain the venom by applying pressure on the toad's paratoid glands, located behind its eardrums. This will cause the toad to ooze the milky substance, which someone may then directly lick off the amphibian or collect to dry and eventually smoke. Taking bufotenine is a crapshoot, however, since people won't know how much of the concentrated toxin they're ingesting until it's too late. That means they could experience mind-altering hallucinations or cardiac arrest and death.

Archaeological evidence points to South American Indian tribes using Colorado River toad venom in religious ceremonies dating back to 1150 B.C.

Excerpt from howstuffworks.com:
https://animals.howstuffworks.com/amphibians/hallucinogenic-frog1.htm

The Colorado River toad, also known as the Sonoran Desert toad is native to Northern Mexico and the Southwestern U.S., including New Mexico, Arizona, and even Southern California. Bufotenine is the active chemical in toad venom. Both the Colorado River toad and the Sonoran Desert toad use venom to paralyze their enemies. If a person licks or smokes a small amount of the bufotenine in the toad venom, they will most likely experience some mind-altering hallucinations, including fast-moving images or blurred vision. Bufotenine contains the chemical 5-MeO-DMT, similar to DMT, a naturally-occurring substance that's often used in the synthetic production of LSD. The chemical interacts with neurotransmitters in the brain of the user, leading to a range of physical and mental side-effects.

Users can react to the psychedelic effects of bufotenine in different ways. Dosing the drug can be difficult, with many users not sure how much they should be taking. In small amounts, the user may experience an altered state of mind and hallucinations. Some users may also experience heart palpitations or see their pupils dilate. But too much and the user could seizure, go into cardiac arrest or even die. The high generally only lasts for around 10 minutes but can be lethal in large doses.

Excerpt from scrubsmag.com:
https://scrubsmag.com/an-exclusive-interview-with-noelia-pena

Erowid Experience Vault:
https://erowid.org/experiences/subs/exp_Bufotenin.shtml

shroomery.org Experiences:
https://www.shroomery.org/forums/showflat.php/Number/17143621

DMT Nexus Experiences:
Bufotenine is definitely very hallucinogenic. The visual effects from it are stronger than any other hallucinogen. But it's hardly "psychedelic", in that there are next to no mental effects unless massive amounts are taken. It's quite unique in that way. It's almost purely visual. It's effects are very unlike 5-MeO-DMT or DMT.

https://www.dmt-nexus.me/forum/Default.aspx?g=posts&t=1699

(PDF 25 pages) Bufo Toads and Bufotenine: Fact and Fiction Surrounding an Alleged Psychedelic:
http://the-eye.eu/public/Psychedelics/Psychedelic%20Praxis%20Library%203.0/Collections%20by%20Substance/5-MEO-DMT%2C%205-HO-DMT%2C%20%26%20Toads/1996%20-%20Bufo%20Toads%20and%20Bufotenine%20-%20Fact%20and%20Fiction%20Surrounding%20an%20Alleged%20Psychedelic.pdf

Bufotenin:

Bufotenin is a chemical constituent in the poison and eggs of several species of toads belonging to the genus Bufo, but most notably in the Colorado River toad (formerly Bufo alvarius, now Incilius alvarius) which is the only toad species in which bufotenin is present in large enough quantities for a psychoactive effect.

• A tryptamine derivative related to the neurotransmitter serotonin
• It is an alkaloid found in some species of toads (especially the skin), mushrooms and higher plants.
• Bufotenin is also known by the chemical names 5-hydroxy-N,N-dimethyltryptamine (5-HO-DMT)
• First isolated from toad skin, and named by the Austrian chemist Handovsky at the University of Prague during World War I

Bufotenin is similar in chemical structure to the psychedelics psilocin (4-HO-DMT), 5-MeO-DMT, and DMT, chemicals which also occur in some of the same fungus, plant, and animal species as bufotenin.

The name bufotenin originates from the toad genus Bufo, which includes several species of psychoactive toads, most notably Incilius alvarius, that secrete bufotoxins from their parotoid glands.