Is Marijuana Harmful? Positive and Negative Effects of Marijuana, Weed

Both negative effects of weed and positive effects of weed are common. But is marijuana harmful or do the positive effects of marijuana outweigh the risks?

The question, "is marijuana harmful?" does not have a simple answer. Marijuana, also known as weed, from the cannabis plant, is known to help some people while it may harm others. Marijuana's harmful effects depend on the individual, the source and why they are using marijuana. Sometimes the positive effects of weed outweigh the negative effects of weed.

Is Marijuana Harmful? - Positive Effects of Weed

The positive effects of marijuana have been known and sought for thousands of years as evidenced by the charred cannabis seeds found at an ancient burial site in modern-day Romania, from third millennium B.C.1 In modern times, the positive effects of weed include both illicit and legitimate uses.

Marijuana is the most widely-used illegal narcotic in the Western world and is used mostly for the positive effects of weed known as a "high." (read: what is marijuana) This intoxication includes positive effects of marijuana like:

  • Euphoria
  • Relaxation, decreased anxiety (read: marijuana and anxiety)
  • Enhanced sensory experiences
  • Laughter
  • Talkativeness

Is Marijuana Harmful? - Medical Uses and the Positive Effects of Weed

Positive effects of marijuana are also seen in medical uses, however (medical marijuana). Marijuana is legal for some medical treatments in Canada and in parts of the US and Europe. Medical use exploiting the positive effects of marijuana has been around for thousands of years. Positive effects of weed commonly used for the medical benefit include:2

  • Decreasing of inner-eye pressure
  • Pain reduction
  • Nausea and vomiting suppression
  • Appetite stimulation

These noted positive effects of marijuana have led to its testing and use in a variety of medical conditions. Evidence strength varies depending on the treated condition, but the positive effects of weed are often used in treating:3

  • Cancer - specifically the pain, nausea, and vomiting associated with cancer treatment
  • Chronic pain - strong evidence for use in cases where other pain medications aren't working
  • Multiple sclerosis (symptoms) - strong evidence for use for pain, muscle spasm and urinary problems
  • Glaucoma - due to marijuana's ability to reduce ocular pressure

Other medical conditions thought to possibly benefit from the positive effects of marijuana include:

  • Eczema
  • Epilepsy
  • Huntington's disease
  • Insomnia

Is Marijuana Harmful? - Negative Effects of Weed

While positive effects of weed can be seen both recreationally and medically, there are many negative effects of weed to also consider.

Some of the main negative effects of marijuana are due to its illicit nature. Because marijuana is illegal, not only can people have legal action brought against them for growing, selling or buying marijuana, but users never know exactly what active compounds are in the marijuana they're using.

Major harmful effects of weed are seen when tolerance develops and marijuana is abused. Once a user becomes tolerant to the effects of a drug, they tend to increase their dosage, increasing the likelihood of marijuana addiction and the other negative effects of weed. The state of tolerance also indicates the user will experience the negative effects of weed withdrawal during periods of drug abstinence. If a user abuses marijuana, the negative effects of weed are seen in the person's life as they choose to use marijuana above all else.

Other negative effects of weed include:4

  • Altered senses
  • Dizziness, tiredness, fatigue
  • Reduced coordination and balance
  • Cognitive impairment (read: marijuana psychological effects)
  • Anxiety, panic, paranoia
  • Hallucinations
  • Mood alterations
  • Altered blood pressure, dizziness
  • Increased heart rate
  • Flushing
  • Dry mouth
  • Nausea, vomiting
  • Tooth discoloration
  • Increased appetite
  • Skin rash
  • Dry eyes
  • Blurred vision
  • Cough, sore throat

More detailed information on how marijuana affects the body and brain.

article references

APA Reference
Tracy, N. (2021, December 15). Is Marijuana Harmful? Positive and Negative Effects of Marijuana, Weed, HealthyPlace. Retrieved on 2024, June 16 from

Last Updated: December 30, 2021

Medically reviewed by Harry Croft, MD

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