Adverse Effects of Cannabis and Cannabinoids

There has never been a lethal overdose from Cannabis or cannabinoids.


Plant-based cannabinoids such as tetrahydrocannabinol (THC) and cannabidiol (CBD) mimic endocannabinoid molecules (e.g., anandamide) that are produced naturally by our bodies.

In contrast to opioid receptors, there are no cannabinoid receptors located in the brainstem areas that control (and can fatally suppress) respiration.

Potential Adverse Effects:

  • Tachycardia (rapid heartbeat)
  • Arrhythmia (irregular heartbeat)
  • Hypotension (low blood pressure)
  • Conjunctival injection (red eyes)
  • Bronchodialation
  • Muscle relaxation
  • Decreased gastrointestinal motility

Withdrawal symptoms are observed in some patients.  However, these symptoms are generally reported as mild compared to withdrawal symptoms associated with opiates or benzodiazepines (or alcohol or tobacco).  These symptoms generally resolve within a few days.

Potential Withdrawal Symptoms:

  • Irritability
  • Insomnia
  • Restlessness
  • Hot flashes
  • Nausea
  • Cramping (rare)

Medical cannabis should be used in consultation with a physician who specializes in cannabinoid medicine.

References and Resources

National Cancer Institute (at the National Institutes of Health, part of the U.S. Department of Health and Human Services).  Cannabis and Cannabinoids (PDQ®) – Health Professional Version.  Adverse Effects. 


About markrabe

Mark L. Rabe, MD, ABIHM Integrative Holistic Medicine Centric Wellness 2308 6th Avenue San Diego, CA 92101 Telephone: (619) 546-0420 Fax: (619) 615-2346 E-Mail:

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