General Information about Marijuana

What is marijuana?

Marijuana is defined by Washington state law as all parts of the plant cannabis, whether growing or not, with a THC concentration greater than 0.3 percent on a dry weight basis. Hashish and hash oil are other products derived from the cannabis plant. Hashish is made from the resin of the plant. Hash oil is obtained from the plant by separating resins from the buds/flowers, using solvent extraction methods. Hashish and hash oil are more concentrated and therefore more potent than smoked marijuana.

The main psychoactive chemical in cannabis is delta-9-tetrahydrocannabinol, commonly known as THC. Marijuana potency has increased significantly over the past few decades, primarily due to changes in how it is grown.

How is marijuana used or consumed?

Marijuana can be:

  • Smoked in hand-rolled cigarettes, pipes or water pipes,
  • Consumed in marijuana-infused food products, usually called edibles, or
  • Through powders or oils.

Smoking  or vaporizing marijuana

Marijuana can be smoked in hand-rolled cigarettes, pipes or water pipes. The effects of smoking marijuana are felt within seconds or minutes. Due to the increased potency of marijuana, it is often no longer necessary for a consumer to take repeated hits or smoke an entire joint to feel the effects.

Vaporizing marijuana is similar to using an e-cigarette. Because vaporizers heat marijuana below the combustion point, it is believed they produce a lower level of tar than cigarettes (Grottenham, 2001). However, more research on the potential use of vaporizers to reduce harm is needed.

It should be noted that marijuana smoke contains a similar range of harmful chemicals as tobacco smoke (Hoffman et al, 1975). Here is a summary of what is known about smoking marijuana based on scientific research:

  • Based on the current scientific research, there is no definitively proven "safe" way of inhaling marijuana (smoke or vapor).
  • Inhaling marijuana smoke in the long-term is likely to result in damage to the respiratory tract.
  • Smoking both marijuana and tobacco increases the risk of damage from both substances.
  • While marijuana smoke contains carcinogens, research about the association between marijuana smoking and cancer is limited and conflicting. The same is true for other lung-related diseases.
  • Marijuana smoking does appear to increase cough, sputum production, airway inflammation, and wheeze.
  • Using a water pipe or bong does nothing to reduce exposure to tar and carcinogens in marijuana smoke; using a vaporizer may reduce the harm associated with smoking marijuana; however vaporizers may carry their own risks and more research is needed.
  • Learn more about respiratory effects at

Edible products
Marijuana-infused food products can be made with the dried, useable marijuana or with concentrated cannabis oil. Edibles made with concentrates tend to be higher in THC and therefore stronger. In addition, it can take up to two hours to feel the effects, making it easier to consume too much. The effects from consuming edibles also last longer, impairing the user for a longer period of time.

Because of their similarity to non-infused products, edibles pose a unique danger to children and pets. To avoid accidental ingestion and poisoning, keep edibles far away from children and pets. 

If your child accidentally ingests a marijuana-infused product or if you are worried about the health and safety of yourself or others, call the Washington Poison Center at 1-800-222-1222 for free, fast, expert help. All calls are confidential. If the symptoms are severe, call 911 or go to an emergency room.

What are the potential health risks of marijuana use?

Although marijuana may help reduce symptoms of certain medical conditions, it also may have some harmful effects depending on how often it is used, who is using it, and whether other substances are also being consumed.

There is clear evidence that regular use of marijuana increases the risk of heart, lung and mental health problems. Less is known about the health issues that might be caused by casual or infrequent use.

What are the short-term effects of using marijuana?

The effects of marijuana may include:

  • A happy, relaxed or “high” feeling
  • Slower reactions
  • Dizziness
  • Trouble with thinking, learning and memory
  • Confusion, anxiety, panic or paranoia
  • Fast heart rate
  • Increased blood pressure
  • Less interest in normal activities
  • Hunger
  • Dry mouth
  • Red eyes
  • Psychosis (rarely) – seeing or hearing things that are not real.

These effects typically last two to three hours after marijuana is smoked or inhaled. When consuming edibles, the effects take longer to be felt (possibly up to two hours) and may last 4 to 10 hours.

Is marijuana addictive?
Contrary to common belief, marijuana is addictive. Estimates from research suggest that about nine percent of users become addicted to marijuana; this number increases among those who start young (to about 17 percent, or 1 in 6) and among people who use marijuana daily (to 25-50 percent). (National Institute on Health)

More detailed information about marijuana and addiction can be found here.

What about marijuana use by women who are pregnant or breastfeeding?
As with alcohol and cigarettes, there likely is no “safe” amount of marijuana use during pregnancy. THC, the chemical in marijuana that makes a person “high,” can pass from mother to the unborn child through the placenta. This means the unborn child is exposed to THC used by the mother. Smoking also passes carbon monoxide to the unborn child, which disrupts the oxygen supply and can result in growth issues, possible premature birth, miscarriage or stillbirth. There is some evidence marijuana use during pregnancy can result in babies with low birth weight, certain birth defects and symptoms similar to fetal alcohol syndrome. THC can also be passed from the mother’s breast milk, potentially affecting the baby.

To learn about marijuana and other potential health impacts, including marijuana and mental health, go to

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