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What are Hallucinogens?

Hallucinogens are a class of drugs that profoundly alter perception, mood, and a host of cognitive processes. They can transport the mind to a world of intensified thoughts and sensory experiences, often vivid and sometimes entirely detached from reality. From natural substances like psilocybin to synthetic LSD, each has unique effects. Wondering how they impact the brain and consciousness? Let's examine the science behind the visuals.
Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Hallucinogens are drugs which affect the central nervous system, producing hallucinations which may be visual, sensory, auditory, olfactory, or tactile. While many drugs can cause hallucinogenic effects, many people use the term specifically to refer to drugs which are taken deliberately with the intent of experiencing hallucinations. Therefore, a drug like LSD is a hallucinogen, whereas an antipsychotic drug like Trifluoperazine which can produce hallucinations is not known as a hallucinogen.

These psychoactive drugs work by disrupting the neurotransmitters in the brain, sending misfired and mixed messages. Depending on the drug and the dosage, someone can experience a variety of hallucinations as his or her brain attempts to cope with the drug, which is often a toxin. In some cases, hallucinogens can actually damage the brain, with repeat use of drugs like LSD being linked with long-term effects like random distortions of the visual field.

The fly agaric mushroom is a psychedelic.
The fly agaric mushroom is a psychedelic.

Researchers tend to break hallucinogens into three basic categories. Deliriants are drugs which induce a state of delirium, characterized by confusion, blurred vision, stupor, compulsive motion, and a dreamlike state. Dissociative drugs interrupt communication between various parts of the brain, causing people to feel disconnected from themselves and the world around them. Psychedelics fundamentally alter perception, distorting the visual field and causing manifestations of things which are not really there. Some cultures believe that psychedelics reveal the hidden nature of the mind.

Hallucinogens produce a variety of hallucinations.
Hallucinogens produce a variety of hallucinations.

Some examples of psychedelics include: ayahuasca, psilocybin, peyote, mescaline, bufotenine, and LSD. Salvia divinorum, fly agaric, and iboga are some instances of well-known dissociatives, while nightshade, henbane, and mandrake can all induce a state of delerium.

Many natural hallucinogens have a very long history in cultures all of the world. Historically, some shamans and other religious officiants consumed hallucinogens in an attempt to communicate with a higher power, or to explore their own minds. The use of such drugs was often tightly controlled, with a religious rather than recreational nature. Today, hallucinogens are most commonly used for recreational purposes, although the religious use of certain hallucinogens such as peyote is protected by law.

Taking the drug LSD may result in visual and auditory hallucinations.
Taking the drug LSD may result in visual and auditory hallucinations.

In many countries, access to hallucinogens is extremely limited by law. Because these drugs are not efficacious in the treatment of medical conditions, and they can be potentially dangerous, some governments have outlawed their production, sale, and possession. People who violate drug laws may find themselves subject to severe punishments. Because some cultures do have a history of using psychoactive drugs in religious practice, special exceptions may be granted to people in certain religions and ethnic groups.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

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Discussion Comments


@Charred - I wouldn’t necessarily characterize everything hallucinogens do to you as destructive. Yes, they block message pathways in the brain, but this is not always bad. What, after all, do pain killers do? They block pain pathways.

They don’t send you tripping, but the principle is the same; hallucinogens just take it to an extreme in my opinion. I wouldn’t recommend research into these drugs for people with normal illnesses.

But if someone is deemed hopeless by medical science, perhaps a brief foray into hallucinogenic drugs, under controlled medical conditions, might not be such a bad thing in my opinion.


@SkyWhisperer - That’s a good point. It’s not something that people like to talk about because talk about religion and spirituality focuses only on God and not the adversary, as if there were only good and not evil in the universe.

I don’t believe God has anything to do with experiences connected to these drugs. The created world is beautiful and majestic enough in its own right, without requiring anyone to “trip out” into a hallucinogenic world.


Some people think hallucinogenic drugs are great spiritual aids. Well, let’s look at that for a moment. If the drugs work by causing your neurons to “misfire” as the article says, then they are not benefiting the brain, are they?

If then you believe that they are an aid to spirituality and enlightenment, then it follows that such spiritually can only occur if you are purposely destroying yourself. Would the experiences you receive be good or bad then?

To paraphrase an old movie, “There is a dark side to the force.” I personally believe that it can open the door to spiritual experiences, but not all of them are good spiritual experiences; there are entities out to destroy you. That’s my take on the shamanism hallucinogen connection.


From what I understand, a lot of shamanic religions favor the use of hallucinogens in their ceremonies. In fact, I read somewhere that the very famous Greek oracles of ancient times maybe have been basically getting high off of gas emissions at the Temple of Delphi and having drug induced visions.

I personally find all the different viewpoints about hallucinogens fascinating. Some people think they're recreational and others think they can bring about a spiritual awakening. Who knows what the real truth is?


@strawCake - I think these days, most people who haven't done drugs still know some people who have and are aware of the possible effects. Even though a lot of hallucinogens are illegal, you can still buy hallucinogens pretty easily in most places.

I have to say though that I've noticed that the popularity of certain drugs tends to fluctuate. For example, I'm 26, and when I was in high school ecstasy and pot were both really popular. I don't know anyone that's ever done LSD, although my mom has told me stories about her friend's adventures with LSD in the 1970s. Everyone my age that I know who does hallucinogens prefers "magic mushrooms."

Sometimes I wonder what wacky hallucinogenic drugs they'll invent next!


I think the thing about hallucinogens is that you never really know how you're going to react to them until you try. I've never personally done hallucinogens, but I have a few friends that have had different experiences with them, so that's where I get my hallucinogen info.

Anyway, one of my friends has tried a few different hallucinogens, and she says she has a different experience each time. The first time she tried 'shrooms, she had a great time, but then the next time she took them she had a horrible experience.

I'm personally too scared to lose control that way. It seems like you're playing a game of chance every time you decide to do a hallucinogen.


@StarJo – It sounds like your friend had a bad trip. My old friend also had a terrifying experience while on LSD, and his was so bad that it sent him to the insane asylum.

He said it started out just weird. A cat in the room sounded just like it was saying, “I know” instead of “meow,” and this made him think the cat could read his mind. Also, a Doberman's nose appeared as long as the room.

Then, it got to be horrible. He looked in a mirror and saw his own face melting off his skull. Then, he was at his funeral, and no one could hear him telling everyone he wasn't dead, so he believed that he was.

He watched himself get buried. One of his friends heard him screaming back in reality and could not console him. He had to be committed, and it took months of therapy for him to be able to function normally again.


I have a friend who says he is a retired hippie. He told me about his experience with dropping acid back in the sixties, and though some of it was beautiful, some sounded terrifying.

He said that beautiful things seemed magnified in their beauty. Colors and light were intensified, and so was pleasure.

However, the flip side was also true. Ugly or scary things were unbearably awful.

He said he saw giant spiders one time, and even though his friend told him they were just regular sized garden spiders, to him, they were as big as a car. This really bothered him, and this was also the last time that he dropped acid.


@lighth0se33 – I've never been around people who have eaten mushrooms, but I have been at a party with friends who drank a punch made from them. I made sure to steer clear of it, because I only came to the party to make sure they all got home safely.

It was pretty bizarre to be the only sober person in a field full of people hallucinating. My friends seemed very happy, and they didn't do anything too outlandish, but I could tell that their mental state was drastically altered.

Obviously, I drove them home. They kept commenting on how close we seemed to the road and how it looked like passing cars were headed right for us. It all made me a bit nervous, but I managed to get them home without anyone deciding to grab the steering wheel or jump out of the vehicle.


I left a group of my friends right before they were about to go eat hallucinogenic mushrooms. I knew what they had planned, and I didn't want to be a part of it.

I did hear about what happened later, though. They all sat around in a dimly lit room, staring at the glow-in-the-dark clock. One of them took the clock off the wall and turned all the lights out.

She then ran through the room, holding the clock, so it appeared to be moving on its on. They though it was pretty hilarious at the time, and they all took turns doing this.

If only fun things like this happened every time they took hallucinogens, then I wouldn't worry. I have heard about bad trips, though, and I fear that one day, one of them will either lose his mind or seriously hurt himself while under the influence.


@stl156 - I've never tried any of these things either, but I have read a lot of autobiographies and stories from musicians who experimented with those types of things.

From what I understand, hallucinogens like LSD are not physically addictive like cocaine, just mentally. In other words, your mind really wants the drugs, but you shouldn't suffer physical withdrawal symptoms. Like you would imagine, if you take hallucinogens, you see strange things that aren't there.

As far as cocaine and other stimulants go, I think they make your mind so active that every sensation you feel is amplified. Just a regular light bulb from a lamp might feel like a spotlight shining in your eyes.

From what I've read, meth is more like a combination of things. It is definitely a stimulant that can keep people awake for days at a time, but I think it can also have hallucinogenic effects. I have read stories of people who have killed themselves on meth because they thought they saw and felt bugs or other things crawling on them.


I never knew there were so many different types of hallucinogens in terms of the effects they could have. I have never taken any recreational or legal hallucinogens, so I am not really familiar with how they act in the body. I would assume it is possible to get a hallucinogens addiction, isn't it? Does they work the same way most other drugs do by making the body produce certain hormones and proteins and then expecting the feelings to constantly continue?

What happens during hallucinogen withdrawal? Are there any specific symptoms that are unique to people who have been addicted to the drugs? I suppose it could also be the case that different drugs have different symptoms.

The other thing I was wondering is what exactly separates hallucinogenic effects from similar effects from other drugs. I have watched videos of people who have taken cocaine and think that things exist that aren't really there. The same is even more true for meth. Cocaine and meth are classified as stimulants, though.


@Emilski - I can't really think of any other common hallucinogenic plants. If I remember correctly from a botany class I took in college, mandrakes are actually a type of nightshade. The interesting thing about nightshades is that there are a lot of them that are very much edible by humans. Tomatoes and tobacco are both in that family.

I'm not a scientist, so I don't know all of the mechanisms that plants use to cause their hallucinogenic effects, but they can affect different animals in very different ways. A lot of plants that are fine for humans to eat aren't fine for other animals. Onions and chocolate are good examples in the case of dogs. I know farmers with horses and cows also have to take a lot of precautions to make sure certain plants are eradicated from their farms.


@turquoise - Good point, and I think I agree with you. There are a lot of ways that someone can have a religious experience without using some type of mind-altering drug. The thing I have always thought was most interesting about hallucinogens and any drug for that matter is how they were discovered. There had to have been a lot of people who died eating poisonous plants to discover the beneficial ones. I'm sure whoever discovered peyote had an interesting experience afterward.

I know peyote is a type of desert plant, but what are some of the other hallucinogenic plants that are common in the United States? I have heard of some of the ones mentioned in the article like nightshade and mandrake, but couldn't tell you what they look like.

Do those types of plants have any historical use as being a type of medicine or anything?


@turquoise- I don't think that hallucinogens are so bad, if they're used in controlled doses. In fact, they might even prove to be beneficial for some psychological disorders.

There are some studies going on right now to find out if hallucinogens could be used to benefit those with terminal illness that have intense anxiety and fear over death. And some of these studies have shown positive results.

Interestingly, the hallucinogen experiences which help these patients are exactly the spiritual feelings that you mentioned. We still need more hallucinogen information but it's possible that doctors might start using limited amounts of hallucinogens for these kinds of treatments.


@anamur-- Yes and no. There have been studies done on this and people do report that hallucinogen effects include spiritual experiences and feelings. Feelings like transcendence, unity and feeling whole with the universe. But trying to experience these spiritual emotions with hallucinogens are dangerous in my opinion.

Because hallucinogens also have psychotic effects on people which includes negative emotions and perceptions you mentioned like distortion of reality, paranoia, fear and panicking. So if someone takes hallucinogens for the purpose of a spiritual experience, there is no guarantee that this is what they're going to get. They could end up having psychotic experiences. They could even have both followed by each other.

So even though some use of it by religious groups is allowed in the US, I think hallucinogens for this or any purpose is unpredictable and risky. I think people could have same or similar spiritual experiences through safe methods like meditation and prayer instead.


Does anyone know more about the religious or spiritual use of hallucinogens? I've always thought that hallucinogens were used only recreationally and always resulted in negative outcomes like fear, nightmare like visions and so forth.

It's shocking to know that people who want to be closer to God or a higher being or who want to discover their subconscious would use hallucinogens.

Do hallucinogens really work this way? Can it really bring people closer to God?

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    • The fly agaric mushroom is a psychedelic.
      By: Jag_cz
      The fly agaric mushroom is a psychedelic.
    • Hallucinogens produce a variety of hallucinations.
      By: vlorzor
      Hallucinogens produce a variety of hallucinations.
    • Taking the drug LSD may result in visual and auditory hallucinations.
      By: sebra
      Taking the drug LSD may result in visual and auditory hallucinations.
    • The production, sale and possession of hallucinogens is outlawed in many countries.
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      The production, sale and possession of hallucinogens is outlawed in many countries.
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      The side effects of deliriants may include blurry vision and a trance-like state.
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      Mixing hallucinogens with alcohol often exaggerates their effect.
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      General anesthesia has been known to cause hallucinations.