Frequently Asked Questions

What are cannabinoids?
CBD and THC chemical structure

Cannabinoids are chemical substances made by the cannabis plant. The best known cannabinoids are THC and CBD; in addition, these plants make smaller amounts of over 100 other cannabinoids.

Tetrahydrocannabinol (THC) is the best known and primary psychoactive (mind-altering) cannabinoid associated with getting “high.” Selective breeding over the last few decades has increased THC levels in cannabis. For cannabis edibles, 10mg of THC is considered a “single serving.” See our factsheet on Cannabis Edibles.

Cannabidiol (CBD) is another cannabinoid commonly heard about. In certain cannabis strains, there may be larger concentrations of CBD, which does not cause a high and has other distinct and positive effects. Until recently, American strains of cannabis contained little or no CBD. This has begun to change as more medical cannabis patients seek strains that are high in CBD and low in THC.

For more about cannabinoids, check out our interactive e-learning module, Our Bodies & Marijuana.

Why do I need to know about percentages of THC and CBD?


THC and CBD on a scale

The percentage of THC is often taken as a measure of cannabis potency (how strong the drug is). It’s possible that very high THC numbers may be more dangerous to the user. However, this would only be the case if someone uses too much. Additionally, if a cannabis sample is of higher potency, a smaller amount may be required to produce the desired effect, which could be a good thing if it means reduced exposure to smoke. Cannabis in the form of butane hash oil (BHO, butane honey oil, wax, shatter or dabs) is extremely potent compared to other forms.

If you try a higher potency cannabis for the first time, it is advisable to use a small amount and wait to see what the effects are before taking more.


Compared to THC, which often makes people sleepy, CBD tends to increase alertness in low to moderate doses. It may also blunt the peak high from THC while mildly prolonging its effects.

CBD has a tendency to reduce anxiety or even paranoia from THC as well. Additionally, research has shown that it may reduce the drug abuse liability (tendency toward addiction) of cannabis. Thus, early research would suggest that having a greater amount of CBD in cannabis may help make it safer.

For more about THC and CBD, check out our interactive e-learning module, Our Bodies & Marijuana.

What should I know about high-THC cannabis products?

High-THC cannabis concentrates, like shatter, wax, butters and oils used for dabbing and also as ingredients to produce vaping cartridges, infused joints, and as the main mind-altering ingredient for edibles. Concentrates contain THC levels varying from 60-90%. These levels are a 6-to-9-fold increase over what was considered “highly potent” cannabis back when the main method of use was smoking the cannabis plant.

Science has shown us that the higher the “dose” (amount) of THC someone uses, the more likely they are to experience negative health effects in response; this is called a “dose-response” relationship.

In 2020, experts from the University of Washington and Washington State University published a report, “Cannabis Concentration and Health Risks: A Report for the Washington State Prevention Research Subcommittee (PRSC),” that identified three primary areas of concern related to these negative health effects:

  • Young people are more vulnerable to high-THC products, especially when it comes to developing “cannabis use disorder” (cannabis addiction).
  • Young adults, people with lower incomes, racial and ethnic minorities, and those reporting poor mental health are more likely to “dab,” the riskiest method of using high-THC concentrates, leading to disproportionate rates of harm among more vulnerable groups.
  • High THC products can have lifelong mental health consequences. Daily cannabis use, especially of high-THC products, increases the risk of developing a psychotic disorder (like schizophrenia) and can worsen symptoms in people with an existing psychotic disorder.

Learn more about the potential health risks and policy recommendations that could help limit harm to public health in our factsheet Policies to Help Limit Harm from High-THC Cannabis Products.

Can getting high cause memory problems?
Head with missing puzzle pieces

Some people who get high a lot say their memory is poor. That’s one of the common reasons people give for deciding to quit using pot.

Here’s what scientists tell us:

  • The THC in pot has the ability to affect cannabinoid receptors, specific sites in the brain.
  • One type of cannabinoid receptor, CB1, is concentrated in parts of the brain associated with memory, such as the hippocampus.
  • For some, being high feels like getting lost in their thoughts, forgetting what they are doing, and not staying concentrated on a goal. This kind of experience is probably due to pot’s effects on short-term memory.
  • On the other hand, scientists also think that long-term daily pot use may cause subtle impairments in memory and attention that persist even when a person isn’t high.

There are different types of memory. For example:

  • Knowing: You know what a cobra is, even though you’re not sure when you saw one in a zoo or read about them in a book.
  • Remembering: You remember what you did on your last birthday, who you were with, and what kind of cake you had. You remember what you studied last week in school.
  • Procedure: You can ride a bike today because you once learned the skills involved.

Scientists think that problems with the second kind of memory can happen when someone is high. It can be particularly difficult to remember recently learned information. This may explain why students who frequently get high may see their school grades suffer, as pot’s effects on memory get in the way of learning.

REMEMBER: Being high can interfere with memory for recently acquired information.

Is driving while high a big deal?
Illustration of driver on road

Many of us know people who are absolutely certain they can drive safely after getting high. You’ll hear them saying, “I’ve done it lots of times and never got into an accident. Besides, I’m really careful.”

The fact is that sometimes they’re right — they’ve driven while high and nothing bad happened.

But here’s the deal: the same thing is true for some people who drive after drinking alcohol. Sometimes they, too, make it home without having an accident.

But, then there are the times when a driver who has been drinking causes a wreck, sometimes hurting or killing others, because the skills they needed to drive safely were impaired. The same is true for pot.

Driving high increases the risk of accidents.

Why? It’s because driving while high can cause impairment such as:

  • Lane weaving
  • Slower tracking of events
  • Divided attention
  • Slower reaction time

Combining pot with alcohol makes these risks of an accident even worse.

Some good ideas:

  • Plan ahead and avoid the need to drive after getting high.
  • If you must drive, give yourself a safety margin and wait at least 3 or 4 hours if you’ve used cannabis by inhaling. But, because ingesting cannabis (for example, eating edibles) delays and prolongs the effects, the safety margin will need to be hours longer.
  • Don’t let anyone convince you to get into a car driven by someone who is high or has been drinking.
  • Don’t put others at risk because of your pot use!

For more, see our topics page on Legal Issues & Safety.

Can I get addicted to cannabis?

Most people who get high do so occasionally. It doesn’t take over their lives, or take priority over responsibilities at home, school, work, or with friends.

For some people, however, their pot use looks a lot like an addiction.

Here are some of the signs:

  • They intend to limit how often they get high, but they break their own rules.
  • They want to cut back or even quit, but they don’t follow through.
  • Being high takes up much more of their time than they want it to.
  • Things that are important to them (friendships, family, school, work, sports, music, etc.) are sacrificed so they can get high instead.
  • They worry about some problems that pot might be causing in their lives, but continue getting high anyway.

Want to minimize your risk of addiction? Keep your use to weekly or less often. For more about addiction to cannabis, see our factsheet on Cannabis Use Disorder.

If you or someone you know wants help, take a look at our Get Help page.

Why should teens hold off on using cannabis?

Some teens get high and think pot’s no big deal. However, doctors strongly urge teens to wait until they are 21 or older before using pot. Why?

It’s because of what is still developing in an adolescent’s brain. Parts of the brain, the pre-frontal cortex, for example, may not develop the way they are supposed to if the person smokes a lot of pot while they are a teen.

What does that mean? It may mean:

  • Problems with memory
  • Difficulty learning
  • A harder time planning
  • Struggling with solving problems

And here’s what makes it more serious: It is possible these problems will be permanent.

There’s more information to think about. Teens who use a lot of pot may have an increased likelihood of depression, anxiety, psychosis, or other mental illness.

REMEMBER: Getting high is legal for adults and it’s tempting for teens. But many teens decide to wait until they’re adults. People who begin getting high before they are adults, and who do it frequently, are risking a lot.

For more, see our Factsheet on Cannabis and Adolescents.

Can using cannabis affect my mental health?
Watercolor of person's head with colors streaming from top

This is an important question, but there’s a lot scientists can’t tell us yet.

Question: Can some people become seriously depressed if they get high, maybe even to the point of committing suicide? What about anxiety or psychosis?

Answer: Yes, but scientists aren’t sure that pot causes these problems. Maybe it’s something else going on in a person’s life that causes these things to happen.

There’s an important exception: People with a vulnerability for or history of psychosis have been found to have higher risk for having a psychotic episode if they get high.

In summary, there’s a possibility of risk to mental health, but more research is needed to clarify this issue.

Question: So how do I take care of myself if I use cannabis?

Answer: Tune in to what your body is telling you:

  • If you seem to be frequently depressed or anxious after getting high, consider the possibility that pot isn’t working for you.
  • If you’re having suicidal feelings and thoughts when you get high, pot could be contributing to this, or, at the very least, not helping. Help is available at
  • If you’re a teen, scientists believe the risk of mental health problems, now and later in life, are greater for you if you get high.
  • Be careful with cannabis that has high THC and low CBD content — it may lead to anxiety or panic.

For more, see our Factsheet on Cannabis and Mental Health.

Do I need to worry about cannabis smoke damaging my lungs?
Illustration of lungs

Question: Are people who smoke pot at risk of diseases of the lung, such as lung cancer or lower respiratory tract infections?

Answer: Scientists have been concerned about this question because cannabis and tobacco smoke have some of the same contents shown to have toxic effects on respiratory tissue.

Question: So, what does the latest research tell us?

Answer: Here are a few of the things we know and don’t know about the effects of cannabis smoke on the lungs:

  • Symptoms of chronic bronchitis are increased by regular cannabis smoking (frequent coughing, sputum production, or wheezing, for example).
  • Airflow obstruction does not appear to be related to cannabis smoking.
  • Bronchodilation can occur when the occasional user inhales THC — this causes decreased resistance in the respiratory airway and increased airflow to the lungs.
  • Chronic Obstructive Pulmonary Diseases (COPD) such as emphysema, do not appear to be caused by smoking cannabis , as long as you are not also smoking tobacco.
  • Pulmonary infection (inflammation in the lungs) may be caused by cannabis smoking — this connection is uncertain and more research is needed.
  • Much more tar from cannabis smoke is deposited in the lungs if someone takes large puffs, inhales it deeply into their lungs, and holds their breath. It’s more tar than the typical user gets from smoking a cigarette.
  • Cancer risk from smoking cannabis is still being studied, with no definitive answers yet. While many studies don’t find an increased risk, it’s still possible there is such a risk for heavier cannabis smokers.

A good idea: Take a look at vaporizers to reduce the risk of lung damage from inhaling smoke. Using edible cannabis products is also an effective way to prevent any lung-related problems.

For more, see our Factsheet on Respiratory Effects of Cannabis .

Is it dangerous to use cannabis during pregnancy?
Illustration of pregnant woman

Just as alcohol crosses the placental barrier, so does THC. But does THC exposure damage the fetus?

The answer is: we don’t know enough yet to be certain about all of the possible risks.

One thing that scientists do believe, however, is that regular cannabis use during pregnancy leads to babies born with reduced weight. Scientists are still looking into some other possible risks to the baby, including behavioral and developmental delays during the baby’s first few months that may persist into childhood and adolescence.

During breast feeding, cannabis consumed by the mother is also consumed by the baby through mother’s milk and may be harmful.

There’s another possibility — one having to do with the parents. For some people, getting high appears to interfere with their ability to reproduce.

DON’T RISK IT! Though we still have many unanswered questions about the risk of exposing your baby to cannabis , the risk is too great. Just don’t do it — don’t get high if you’re pregnant and don’t get high while you are breastfeeding. Also, if you and your partner are unsuccessful in trying to get pregnant and either or both of you are getting high regularly, pot use might be getting in your way.

For more, see our Factsheet on Cannabis and Reproduction/Pregnancy.

Give me a quick overview of what I need to know.

Adults who don’t have heart disease or psychiatric conditions, don’t get high during pregnancy or use when it’s dangerous, and use pot occasionally probably aren’t at risk of any harm to their health. But, keep these things in mind:

  • First time cannabis users may experience anxiety or panic. Use a small amount at first and wait an hour (two hours if consuming edibles; see our factsheet on Cannabis Edibles) to see how it affects you. Going slowly will help you safely determine how much is enough to produce the desired effect.
  • If inhaling, take shallow puffs rather than inhaling deeply in order to reduce exposure to harmful smoke.
  • Cannabis with high levels of THC and low levels of CBD may make anxiety or panic more likely.
  • Driving while high can cause accidents due to impaired attention, reaction time, and other skills needed for safe driving.
  • Using pot during pregnancy may lead to lower birth weight of the baby and other complications.
  • Becoming dependent on pot happens to 33% to 50% of daily users. Teens who begin early are at greater risk of becoming dependent and other problems.
  • People vulnerable to psychosis are at risk of a psychotic episode if they use pot.
  • Regular pot smoking contributes to chronic bronchitis (wheeze, chronic coughs).
  • Older adults with heart disease are at increased risk of angina and heart attack after pot use.
  • Use during adolescence can cause a number of learning problems that may become permanent.
  • Store cannabis (especially edibles) safely so that it is not attractive to or in reach of children and pets.
  • Reduce risk of becoming dependent by using no more than once weekly.

FAQ prepared by Roger Roffman, DSW, University of Washington.