People have been taking LSD for decades, but experts still don’t know all that much about it, especially when it comes to how it affects your brain.

Still, LSD doesn’t appear to kill brain cells. At least, not based on the available research. But it definitely does get up to all sorts of other things in your brain.

Healthline does not endorse the use of any illegal substances, and we recognize abstaining from them is always the safest approach. However, we believe in providing accessible and accurate information to reduce the harm that can occur when using.

LSD influences serotonin receptors in the brain. Serotonin is a neurotransmitter that plays a role in every part of your body, from your mood and emotions to your motor skills and body temperature.

According to a 2016 study, LSD also causes changes in the brain’s blood flow and electrical activity. The same study also suggests it increases areas of communication in the brain.

Together, these effects on the brain can result in:

  • impulsiveness
  • rapid mood changes that can range from euphoria to fear and paranoia
  • altered sense of self
  • hallucinations
  • synesthesia, or a crossing of the senses
  • increased blood pressure
  • fast heart rate
  • increase in body temperature
  • sweating
  • numbness and weakness
  • tremors

How long do these effects take to set in?

The effects of LSD begin within 20 to 90 minutes of ingestion and can last up to 12 hours.

But as with any other drug, everyone responds differently. How much you take, your personality, and even your surroundings affect your experience.

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So far, there’s not much evidence to suggest that LSD has long-term effects on the brain.

People who use LSD can quickly develop a tolerance and require larger doses to get the same effects. But even this tolerance is short-lived, usually resolving once you’ve stopped using LSD for several days.

The big exception here is the association between using LSD and other hallucinogens and the development of psychosis and hallucinogen persisting perception disorder (HPPD).


Psychosis is a disruption of your thoughts and perceptions, resulting in an altered sense of reality. It makes it hard to tell what’s real and what isn’t. You may see, hear, or believe things that aren’t real.

We’ve all heard stories about someone who took LSD, had a super bad trip, and ended up never being the same. Turns out, the chances of it happening are pretty slim.

LSD and other substances can increase the risk of psychosis in people who already have a higher risk for psychosis than others.

A large survey published in 2015 found no link between psychedelics and psychosis. This further suggests there are other elements at play in this connection, including existing mental health conditions and risk factors.


HPPD is a rare condition that involves having repeated flashbacks, which are described as reexperiencing some of the effects of the drug. They might include certain sensations or visual effects from a trip.

Sometimes, these flashbacks are pleasant and feel good, but other times, not so much. The visual disturbances can be particularly unsettling and interfere with daily activities.

In most cases, LSD-related flashbacks happen once or twice, usually within a few days of use, though they can also show up weeks, months, and even years later.

With HPPD, however, flashbacks happen repeatedly. Again, it’s thought to be pretty rare. It’s hard to really know, given that people often aren’t open with their doctors about their drug use.

The cause of the condition is still unknown. People may have a higher risk if they, or their family members, already have:

  • anxiety
  • tinnitus (ringing in the ears)
  • concentration issues
  • eye floaters

Bad trips have nothing to do with it

It’s a common belief that a bad trip causes HPPD, but there’s no evidence to back it up. Plenty of people have had bad trips on LSD without going on to develop HPPD.

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The term “permafried” — not a medical term, by the way — has been around for decades. It refers to the myth that LSD can cause permanent brain damage or a never-ending trip.

Again, we’ve all heard the horror stories of someone who was never the same after they used LSD.

Based on case studies and other research on LSD, HPPD is the only known effect of LSD that bares any resemblance to the “permafried” myth.

A recent in vitro and animal study found that microdoses of LSD and other psychedelic drugs altered the structure of brain cells and promoted the growth of neurons.

This is significant, because people with mood and anxiety disorders often experience shrinkage of neurons in the prefrontal cortex. That’s the part of the brain responsible for emotions.

If these same results can be replicated in humans (emphasis on if), LSD may help reverse the process, resulting in improved treatments for a range of mental health conditions.

There’s no evidence to support the claim that LSD kills brain cells. If anything, it might actually promote their growth, but this hasn’t been shown in humans yet.

That said, LSD is a powerful substance that can lead to some frightening experiences. In addition, if you already have a mental health condition or risk factors for psychosis, you’re more likely to experience some potentially distressing effects afterward.