Everyone’s heard rumors about cannabis having the wrong effect on some people. Snopes talks about old wives’ tales that smoking too much pot will make you lose your mind. 

The question is, what’s the truth behind those rumors? 

The answer could be drug-induced psychosis or HPPD (hallucinogen persisting perceptual disorder)

Both of these disorders can happen after heavy cannabis use. They’re rare unless you have certain risk factors. 

They share a few similar symptoms, including seeing things that aren’t there. 

The differences are that: 

  • Drug-induced psychosis is usually acute or goes away once you’re not under the influence anymore
  • HPPD is typically chronic or long-lasting, even when you’re not high anymore
  • Drug-induced psychosis includes behavioral symptoms, like paranoia and agitation
  • HPPD causes perceptual symptoms, such as seeing fractal patterns or seeing trails behind moving objects

Learn how cannabis can cause these disorders:

What is Acute Drug-Induced Psychosis?

Drug-induced psychosis is a rare side effect of cannabis. It’s more common with stimulant drugs, like cocaine. 

The effects include: 

  • Agitation
  • Delusions
  • Hallucinations
  • Mood changes
  • Paranoid behavior

Drug-induced psychosis goes away when the drug leaves your system. It usually doesn’t last longer than a few hours. 

With cannabis, psychosis is usually a result of mixing drugs or taking too much. Taking cannabis with stimulants or psychedelics can increase the risk. 

The ingredient in weed that makes you feel high is tetrahydrocannabinol or THC. Too much THC can cause adverse effects in some people. Some strains of weed have more THC than others. High-THC dosing could be a risk factor for psychosis. 

Most of the time, the psychosis goes away on its own when the drug wears off. If treatment is necessary, antipsychotic drugs can stop the symptoms. 

Still, drug-induced psychosis can be a medical emergency. Delusions can make you want to harm yourself or hurt other people. Call 911 if someone who’s with you has drug-induced psychosis. 

What is Hallucinogen Persisting Perceptual Disorder?

Hallucinogen persisting perceptual disorder (HPPD) is a rare visual disorder. It sometimes happens after taking empathogenic drugs. It occurs in up to 5% of regular users of psychedelic drugs. 

It’s more common after taking acid, but it can happen after heavy cannabis use. 

The symptoms are visual flashbacks of things that the user “saw” while using drugs. A person with HPPD may see: 

  • Blurred patterns
  • Halos around lights
  • Intense colors
  • Light fractals
  • Movement outside of your field of vision
  • Trails behind moving objects
  • Visual static

HPPD can happen intermittently or constantly. It’s usually permanent, though a case study says Lamictal may stop symptoms. 

Like cannabis-induced psychosis, HPPD is rare with marijuana use. It usually happens with psychedelic drugs. However, cannabis has psychedelic properties when you combine it with certain drugs or take high doses of THC. 

It’s more likely that you’ll get HPPD if you:

  • Use cannabis with psychedelic or empathogenic drugs like acid, mushrooms, or molly
  • Use cannabis often and in large doses
  • Use high-THC cannabis
  • Have risk factors for psychosis, such as poly-drug abuse or mental disorders

How Does Cannabis Cause Psychosis and HPPD?

By itself, it’s doubtful that cannabis will cause psychosis or HPPD. Cannabis doesn’t have psychedelic properties unless you take large amounts of THC (or combine it with other drugs). 

Instead, it’s several factors that put you at high risk for developing these conditions. 

They include: 

  • Your mental health history
  • Your use of other drugs

What Are the Risk Factors for Psychosis and HPPD?

You may be at higher risk for psychosis or HPPD after using cannabis if you: 

  • Have a history of psychosis
  • Have bipolar disorder
  • Have schizophrenia
  • Use other drugs, including stimulants, psychedelic drugs, and empathogenic drugs

Cannabis and Bipolar Disorder

People with bipolar disorder may have a high risk of adverse effects from cannabis

It’s uncertain why, but we do know that cannabis and bipolar disorder both affect serotonin and dopamine. These are chemicals in the brain that affect mood and other functions. 

Cannabis and Schizophrenia

People with schizophrenia develop HPPD and psychosis at a higher rate than other people. 

That means they’re at high risk for psychotic symptoms if they use cannabis. 

Cannabis and Other Drugs

Your risk of developing HPPD increases if you combine these drugs with cannabis: 

  • Stimulant drugs, such as cocaine or amphetamines
  • Psychedelic drugs, such as LSD or mushrooms

Get Treatment for Cannabis Addiction

True, cannabis doesn’t cause dependence. But that doesn’t mean it’s not an addictive substance. 

Anyone can develop an addiction to any substance, whether it causes dependence or not. That’s because addiction is psychological. Don’t wait any longer to get help for your cannabis problem!


  1. Cannabis use and the risk of developing a psychotic disorder. (n.d.).
  2. Hallucinogen-persisting perception disorder. (n.d.).
  3. A persisting perception disorder after cannabis use. (n.d.).

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