Psychedelics and Health Risks

Psychedelics and Health Risks

Published on:

November 27, 2023

Psychedelics and Health Risks

Even though psychedelics are generally well tolerated, each person needs to understand their own unique risk-benefit profile so they can make an informed health decision. An 'informed' decision suggests you know all the potential risks and potential benefits, however with psychedelics, no one can quite predict what is going to happen and so any outcome is possible. With good medical screening and good process most people have an ideal experience but this is not guaranteed so if you choose to use psychedelics, you are choosing to embrace the inherent uncertainty. Nonetheless, this next section will describe the most common psychological and physical risks associated with psychedelic experiences. By understanding these, you can better understand the risks associated with psychedelic use.

Here is a general outline of what will be reviewed: 

Psychological risks (ref): 
  • The Difficult Experience
  • Anxiety, panic and depersonalization 
  • Reliving Trauma
  • Ego dissolution
  • Drug-induced psychosis
  • Hallucinogen persisting perception disorder
  • Comparing Drug Risks: dependence, addiction and harm
  • Acute Drug Toxicity / Overdose risk
  • Serotonin Syndrome
  • Hypertension, cardiovascular disease
  • Emergency medical treatment
  • Behavioral Risks

Potential Psychological Health Risks: 

The Difficult Experience

  • The primary psychological concern with psychedelics use is referred to as ‘bad trip.’ A bad trip can be characterized as transient experiences of intense fear or grief, an experience of rebirth or death, reliving personal trauma, feelings of insanity, isolation, physical distress and paranoia (ref). Within each of these domains, journeyer’s may experience anxiety, panic or depersonalization all of which appear to subside often within minutes, but for some, 24 hours or less after the experience. (ref, ref). These difficult experiences appear to occur when journeyer’s do not tend to the set and setting (ref), have higher levels of trait neuroticism (ref) or consume other recreational drugs at the same time. 
  • Noteworthy, in those who have a ‘bad trip’, up to 84% report having still positively benefited from the experience (ref, ref). Categorically these ‘bad trips’ are often reframed as ‘difficult’ or ‘challenging’ experiences that have potential to lead to changes in well-being with the aid of integrative practices. In some instances people need to seek help from a medical professional such as a counselor or psychologist to help them work through, make sense of and process the content. Whether someone has had a good or difficult experience, it can be beneficial to connect with a mental health provider to help integrate the experience. You can also consider calling the Fireside Project, a psychedelic support line for assistance as well. 

Difficult: Reliving Trauma

  • Journeyer’s who have experienced significant trauma often report experiencing these memories and associated emotions during their psychedelic journey. Psychedelics are know to take us towards our shadows. While using psychedelics such as psilocybin or LSD, and in particular with MDMA, these traumatic memories are often met with less or without anxiety (ref) leading to positive therapeutic outcomes. After the experience, this may not be the case - it is still incredibly challenging to interact with these memories and their associated symptomology.
  • Importantly, the opposite can be true - journeyer's may experience intense fear or panic and require sometime after their journey to stabilize again. It is recommended that those who have experienced trauma to work with a registered mental health professional prior to a psychedelic experience to ensure the journeyer is equipped with the right tools to process and integrate the material safely and learn the skills necessary to navigate trauma. 
  • If you are having difficulties or experiencing one or more of the following symptoms after your psychedelic experience for more than 1-week, seek help from a medical professional: you are easily startled or frightened, always on guard for danger, engage in self-destructive behavior, have trouble sleeping, trouble concentrating, are irritable, are quick to anger or lash out with aggressive behavior, experience overwhelming guilt or shame, have intrusive thoughts or overwhelming fear. You are avoiding activities or places that trigger memories of the event, social isolation and withdrawal, lack of interest in previously-enjoyable activities.

Difficult: Ego Dissolution

  • Another aspect of a journey that can be difficult is the experience of ego dissolution. Ego dissolution, sometimes referred to as ego death or ego disintegration, is common, occurs at higher psychedelic doses, and is where the conceptual boundaries of ‘I’ or ‘self’ disappear, blurring the boundaries between the body and the world, increasing feelings of unity and ‘oceanic boundlessness’ (ref). The greater degree of ego dissolution may be related to greater therapeutic outcomes (ref). Resistance to this aspect of the journey can lead to a difficult experience and so it becomes important to let go, be open and surrender to it. 

Drug-Induced Psychosis

  • Those who have or have a family history of schizophrenia, bipolar or borderline personality disorders may trigger a drug-induced psychosis and therefore should not use psychedelics. Drug-induced psychosis (DIP) which may include symptoms of delusions and or hallucinations appears to occur more frequently with cannabis and hallucinogen use compared to alcohol, opiate and sedative use (ref). Although DIP is a rare event, it is a risk and may not preclude those who have no history of the aforementioned psychiatric conditions.  

Hallucinogen Persisting Perceptual Disorder

  • Another rare psychological adverse reaction is the development of Hallucinogen Persisting Perceptual Disorder (HPPD) (ref). More commonly referred to as ‘flashbacks’, HPPD is a condition resulting in transient visual hallucinations from the drug experience weeks, months or years after psychedelic use. There are no well established risk factors for this condition (ref). Consider that the reason this is a rare side-effect is because it may be under-reported. There is a support group for HPPD.

Comparing Drug Risks: 

  • Legal drugs such as alcohol and tobacco and illegal drugs such as crack cocaine and heroin appear to produce far greater numbers of psychological and physical harms when compared to psychedelics (ref). According to the National Survey on Drug Use and Health, 19.7 million American adults had a substance use disorder in 2017 with 74% of them suffering with an alcohol use disorder (ref).
  • Alcohol, tobacco, crack cocaine and heroin are commonly known to create dependence. Additionally, these drugs are also known to result in high numbers of drug-specific mortality, physiologic harm and psychological harm to themselves and others especially when compared to psychedelics (ref, ref). Dependence and other harms from these drugs may in part be due to their affinity for dopaminergic neurons that primarily activate the reward centers of the brain (ref). However, dependence and addiction is also largely attributed to an interplay between a person’s genetics, the environment, and early life exposure (ref). To this end, there is no significant body of literature demonstrating the addictive nature of psychedelics, however, there is a small body of research looking at the potential of psychedelics to treat addiction disorders such as smoking (ref) and alcohol dependence (ref). 
  • With psychedelics tolerance develops quickly, commonly does not lead to symptoms of withdrawal and therefore is not commonly a class of drugs that leads to dependence and addiction (ref, ref). Psychedelics appear to rarely lead to physical or psychological dependence with acute and chronic adverse effects being relatively infrequent and generally, mild (ref, ref).
  • Because psychedelics exert their effects primarily through the serotonergic pathways versus the dopaminergic pathways, it has been suggested there is less addiction potential (ref). Also, because psychedelics occasion profound and intense experiences, it is this characteristic that motivates users to have significant time gaps between each journey.


  • To summarize, the one primary risk associated with psychedelic use is the difficult experience. Despite the difficulty, these experiences often lead to personal growth. There are two rare risks that may occur, drug-induced psychosis and HPPD. 
  • Psychedelics are drugs people quickly develop tolerance to, do not result in symptoms of withdrawal, have an affinity to serotonergic versus dopaminergic receptors, and produce intense experiences, provide some insight into why psychedelics are not typically viewed as drugs of abuse. 
  • Experts recommend those who have had a difficult experience to process the event through integration practices (ref) Some people may choose not to discuss the nature of their journey in part due to stigma but also due to not having the tools or support(s) to do so. Having the right tools after a psychedelic journey is a critical step to reducing any short or long term negative effects and to increase the potential for benefit and personal growth (ref). To learn more about what to do after your psychedelic experience, refer to the Integration Guidebook. 

Physical Adverse Events: 

Acute Drug Toxicity

  • The primary physical safety concern with psychedelics is acute drug toxicity. Psilocybin and LSD are referred to as indolealkylamine hallucinogens which are compounds that have an affinity for serotonin receptors. Indolealkylamines are generally well tolerated, are considered ‘low risk’ for toxicity, and is one reason why there are no known reports of overdose reported in the literature (ref, ref). One study suggested the lethal dose of psilocybin in humans has been estimated at 1000 times an effective dose, which is an amount that is likely not possible for an individual to consume when in the form of psilocybin-containing mushrooms. (ref)
  • A “therapeutic index” (TI) is a ratio that compares the blood concentration at which a drug becomes toxic and the concentration at which the drug is therapeutic (ref) to estimate a margin of safety. In general, a higher TI score indicates a better safety profile. Conversely, if a TI is small (the difference between the two concentrations is very small), the drug must be dosed carefully and the person receiving the drug should be monitored closely for any signs of drug toxicity (ref). 
  • Indolealkylamines such as LSD and Psilocybin TI score is approximately 1000 suggesting a low risk of toxicity (ref). For context, cannabis has a TI score just greater than 1000, while alcohol, cocaine, MDMA and codeine have a TI score of 10, 15, 16 and 20 respectively (ref). Importantly, a drugs TI score is influenced by the set, setting and social context. For example, if a drug user is in an environment with other users that use at abusive levels, the risk for toxicity increases. Alcohol, although TI is 10, this can change if a person has a genetic predisposition to addiction, use too frequently, mix with other drugs or drive a car. 
  • MDMA can be used safely, although its risk for toxicity is higher when compared to psilocybin and LSD. Taking too much MDMA and mixing it with other drugs can lead to serious life threatening complications such as serotonin syndrome and other adverse health events (ref, ref). It is also known that taking MDMA with prescribed medications such as monoamine oxidase inhibitors or even caffeine and alcohol can increase risk of a poor, toxic and even lethal experience. 
  • It has been suggested that the main risk with MDMA comes from the misguided idea that a user must consume lots of water to avoid overheating. This leads to hyponatremia or water toxivity. 1-2 cups of water per hour is often all that is needed when dancing, but within the context of a private setting while lying down, perhaps 1 cup per hour is all that is needed. Studies also show that MDMA impairs thermoregulation and when paired with a warm environment and dancing for extended periods of time could lead to hyperthermia. This again is less of a risk in the private setting while lying down.

Serotonin Syndrome

  • Serotonin Syndrome is a drug reaction due to too much serotonin in the central nervous system. Serotonin syndrome presents as a collection of signs and symptoms that occur along a spectrum from mild to severe resulting in mental status changes, autonomic hyperactivity, and neuromuscular abnormalities (ref). 
  • When taking a psychedelic in isolation, Serotonin Syndrome is rare and seems to occur when a psychedelic is combined with a serotonergic drug, one of which is generally a monoamine oxidase inhibitor (ref, ref). 
  • Because combining psychedelics and other serotonergic drugs such as SSRI’s, SNRI’s and MAOI’s may have negative interactions, it is recommended journeyer’s discuss with their primary healthcare provider if psychedelics are right for them and if it is, how to taper from these medications two to six weeks prior to the experience, if this is a possibility. 


  • Psilocybin, LSD and MDMA all result in modest increases in blood pressure and heart rate when compared to placebo (ref). It is therefore recommended that those who have an uncontrolled heart condition or uncontrolled hypertension do not take psychedelics in case of a cardiovascular event. Additionally, psychedelics also raise body temperature and increase pupil size, both of which are transient and benign. 

Behavioral Risks:

  • Psychedelics can be disinhibiting and therefore journeyer’s may engage in risky behaviors they would not otherwise engage in such as climbing, driving, cycling or sexual acts. Having a sitter during the psychedelic can help ensure the journeyer’s safety. 
  • Journeyer’s may be more likely to share secrets or other personal information they would not otherwise share. Additionally, journeyer’s may not be able to provide valid informed consent and be more suggestible. With both of these scenarios in mind, having a sitter that you trust, that is non-judgemental, and supportive will be paramount here. 

Emergency Department Visits:

  • For psilocybin and LSD, there are very few cases that present to the emergency department. In one recent study, 0.2% and 1.0% of reported psilocybin and LSD users respectively sought emergency medical treatment, commonly presenting with symptoms of anxiety, panic, paranoia and suspiciousness (ref, ref). Poor ‘mindset’, poor ‘setting’ and mixing substances were the most reported reasons for incidents (ref). Most medical events reported had cleared up within 24 hours. 
  • Emergency department reports describe patients who use ‘ecstasy’ in a large variety of dosages, often in combination with other substances such as alcohol, GHB or cannabis (ref). The most severe clinical signs from MDMA were hyperthermia, hyponatraemia and agitation, all of which are more likely to occur at doses greater than 120mg (ref) or when mixing substances. Of note, this data does not confirm if patients were using recreationally at parties or festivals, or confirmed through toxicology reports of the purity of the substance.


In summary, psilocybin and LSD appear to have a low risk for drug toxicity. MDMA carries a higher risk for toxicity, but seems to be tolerated well and can be used safely. Psilocybin, LSD and MDMA all result in modest increases in blood pressure and heart rate when compared to placebo. Psychedelics are disinhibiting and may lead to risky behaviours. Also, psychedelics make it difficult for journeyers to provide valid informed consent. Because psychedelics have a low toxicity potential, are drugs people quickly develop tolerance to, do not result in symptoms of withdrawal, have an affinity to serotonergic versus dopaminergic receptors, and occasion intense experiences provides some insight into why psychedelics are not typically viewed as drugs of abuse. If you have questions about any of the risks, we encourage to bring these up with your primary healthcare provider.