National Drug Strategy
National Drug Strategy

Comorbidity of mental disorders and substance use: a brief guide for the primary care clinician

3.1 Cannabis/ hallucinogens

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Table of contents

Cannabis (marijuana, hash, grass, dope)
Lysergic acid diethylamide (LSD, acid)
Psilocybin (magic mushrooms)
Datura (angel's trumpet)
Anticholinergic drugs, (benztropine, benzhexol, orphenadrine)


Cannabis is by far the most commonly used hallucinogen. Cannabis is derived from the hemp plant and contains the active substrate tetrahydrocannabinol (THC). THC exerts its effects via the central nervous system producing a mixture of hallucinogenic, delusional and depressant effects along with other centrally-mediated peripheral autonomic effects.

The drug is often used in group settings as it enhances sociability and at low doses causes a high that includes feelings of relaxation and happiness. In larger doses (larger amounts, parts of the plant with higher concentration, more potent cultivars), cannabis may produce effects similar to LSD.

LSD is a hallucinogenic or psychedelic drug. LSD and regular cannabis use can trigger underlying mental disorders and produce delusions, paranoia and schizophrenia-like states, particularly in people with a family history. These substances can also produce extreme anxiety states or panic attacks, not only while the person is under the influence of the drug, but for some time after.

Psilocybin causes similar effects to LSD; however, these effects are not usually as intense or long lasting. Anticholinergic drugs, e.g. benztropine, benzhexol or orphenadrine may be prescribed to alleviate extrapyramidal symptoms in patients with psychosis. However, these drugs may themselves lead to hallucinations and are therefore sometimes sold for recreational use. Several psychotropic drugs have less marked anticholinergic effects, e.g. tricyclic antidepressants or thioridazine, and may interact with prescribed or illicit drugs to produce an anticholinergic psychosis.

Effects sought from the substance:
Cannabis: Relaxation, increased appetite (and antiemetic effects), feelings of happiness, analgesia, sleepiness as well as feelings of sharpened sensory awareness. Hallucinogens: (e.g. LSD and psylocybin): Perceptual changes such as hallucinations.

Associated harms:
Cannabis: Hallucinations, anxiety, panic attacks, paranoia, nausea, impaired judgment and motor coordination, dependence, reduced motivation, persistent cognitive impairment while using the drug, acute and chronic lung problems.
Hallucinogens (e.g. LSD and psylocybin): Dissociation, disordered thought, flashbacks and frightening hallucinations and delusions which can lead to violence.

Overdose:
Cannabis: Risk is small.
Hallucinogens (e.g. LSD and psylocybin): LSD is not so much associated with overdose; however, a 'bad trip' may result in hallucinatory experiences which take on a menacing quality accompanied by paranoid delusions, often resulting in accidental or intentional self harm.

Withdrawal:
Cannabis: Unlikely although symptoms may include anorexia, disturbed sleep, irritability and moodiness.
Hallucinogens (e.g. LSD and psylocybin): There is little evidence of dependence, and therefore withdrawal, as drugs tend to be aversive rather than reinforcing.

Psychological presentations commonly associated with use (likely to resolve on cessation of substance use):
Cannabis: Depression(4-6), anxiety(6-13), precipitation of psychotic symptoms(2, 14, 15).
LSD: Precipitation of schizophrenia.

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