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Answers to FAQ about the effects of marijuana

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Get scientific answers to the most popular questions asked on the internet about marijuana.  CJ Liu interviews Dr. Scott Swartzwelder from Duke Institute for Brain Sciences about the 4th edition of the book he recently co-authored “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy”.

Answers to FAQ asked on the internet about Marijuana

Marijuana facts: Marijuana strains, Different grades, medical marijuana, synthetic marijuana, marijuana as a depressant?

*Marijuana Varieties and strains:

According to “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy”, there are three grades of pot:

  1. Low-grade marijuana – product of all leaves from both sexes of the cannabis plant.
  2. Medium-grade – product of the dried flowering tops of the female cannabis plant raised with and fertilized by male plants.
  3. High-grade (Sinsemillia) – product of the flowering tops of the female plant raised in isolation of male plants. Powerful marijuana called “hospital pot” will have two to three times the amount of THC. Anyone taking potent marijuana should be aware that it could often result in powerful and sudden highs, which may land unsuspecting smokers in the emergency room with panic attacks.

Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014): p 171

*VIDEO: Describes why pot on street is so strong and importance of legalized marijuana

Dr. Scott Swartzwelder talks about how marijuana sold on the streets today is much stronger than marijuana from the past. He also touches on how states where marijuana is legalized (WA, CO) have much safer pot due to the regulations that were put into place and why different strains of marijuana create different highs and have more variability than you’d expect?

*What is synthetic marijuana? What are the risks in using it?

Here are some quick notes and paraphrasing from “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” about synthetic marijuana. Synthetic marijuana has many names such as, Spice, K2, fake weed, Yucatan Fire, Skunk, Moon Rocks, Black Mamba, Mr. Smiley, Incense, and Blaze. My sense is that buyers should be very cautious when trying the synthetics that have often been described by authors as containing a grab bag of psychoactive compounds that don’t actually contain marijuana.

The authors further explained that while the packages may state “all natural ingredients”, the actual product is dried plant material not marijuana. With these synthetics you may experience some of the same pleasant effects as marijuana (relaxation and altered perceptions), but don’t be surprised of potential unpleasant effects such as, paranoia, hallucinations, extreme anxiety, agitation and confusion.   Other effects noted by the authors include vomiting, rapid heart rate, increased blood pressure, and decreased blood supply. If you’re still not convinced to not try this, consider this last reason: Many of the new fangled compounds contained in synthetics are unfamiliar to the folks in the medical community which makes it more difficult for doctors to respond swiftly in emergency situations.

* VIDEO:Dangers of synthetic marijuana

Dr. Scott Swartzwelder shares the danger of synthetics (

Finding and Using Marijuana: Marijuana Edibles, Marijuana dispensaries, Marijuana vaporizer

*How safe are dispensaries?

Are all medical marijuana facilities safe?

*What is a marijuana vaporizer?  What is the difference between ingesting, smoking or vaporizing pot?

Here is a quick summary and paraphrasing from the “Drug Basics” chapter in “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” about the different ways of taking drugs that will impact how quickly and strongly a drug impacts you (Kuhn, Swartzwelder, Wilson, p319).

Inhaling drugs through a vaporizer or smoking marijuana joints into the lungs delivers the quickest effect. When you inhale a drug, it dissolves through air sacs of the lungs and into the capillaries.  Because the surface area of the lungs is very large and the blood supply of the lungs goes directly to the heart and then out to other tissues, the levels of drug rise very rapidly and can affect you in minutes.  A benefit of vaporizing pot is that it does not create smoke that can be irritating to the lungs and create a “cough”.  However, one of the downsides of vaporizing is that it’s hard to gauge intake.  One thing to note if you inhale marijuana is that the amount of THC that enters into the body varies from 10-20% of THC for cigarettes versus 40-50% of THC for a pipe.

Ingesting a drug requires the drug to pass through the walls of the stomach or intestine and then enter the capillaries.  A large part of any drug is removed by the liver, the organ that rids the body of toxins. Other creative or appetizing ways of using marijuana, such as ingesting a brownie or a gummy, may appeal to your palette but the high can last for hours.  You may be disappointed to find yourself peaking out 3 hours later. Another caution about ingesting is that people often consume a higher quantity at the onset and, as a result, consume greater amounts of THC than they would by smoking.

So, why does any of this matter?  Smoking or inhaling can result in the drug hitting too quickly and reaching a dangerous drug level before you are able to respond appropriately and get help. Eating marijuana offers a more gradual high and may last for much longer durations than you are expecting.  Plus, some experienced smokers feel that eating marijuana gives a different experience that is more akin to a mild mushroom or LSD trip.

*VIDEO- Different kind of highs you will get based on smoking or eating pot

What happens if you smoke, vaporize, or eat marijuana?  Why does one give me a faster high? ( some people don’t like eating marijuana?  (  Why vaporizers have less carcinogens? (

*How to get marijuana out of your system?

THC remains in the body for a long time.  Listen to the video with Dr. Scott Swartzwelder for advice on how long before you get a clean reading for a pre- employment drug screen.

*VIDEO: How do you get the buzz to stop?

*How long does marijuana stay in your system?   How long does marijuana stay in your system? How long does marijuana stay in your blood? Your urine? (The book mentions it’s in your fat)

In the section of “How THC Moves through the Body” in “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” the author explains that you may feel the effects on heart rate and blood vessels in minutes:

In a few hours of smoking, the THC dissipates from the brain but accumulates in significant concentrations in the liver, kidneys, spleen, and testes.  While the high may wear off in a few hours, about half of the THC is still in the blood twenty hours after smoking. Some of the effects of marijuana on mental and physical functions may last for days. Once the blood that is carrying THC passes through the liver, some of the THC is converted into other compounds and may remain there for several days. THC stays in fatty deposits of the body much longer because it is easily absorbed by and stored into fat.  Any THC that is stored in fatty deposits is released over a long time before being eliminated. Bottom line, about 30% of ingested THC (and its metabolites) can remain in the body a full week after smoking. Remnants from a single large dose of THC may be detectable up to three weeks later.  Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014) p173.

*VIDEO:  How to avoid a positive drug test?  (

*Pregnancy and Marijuana? Effects on Reproduction

In the section of “How THC Moves through the Body” and “The Reproductive System” in “Buzzed:The Straight Facts About the Most Use and Abused Drugs from Alcohol to Ecstasy” the author explains that you may feel the effects on heart rate and blood vessels in minutes.

THC crosses from the blood of a pregnant woman into the placenta and reaches the developing fetus.  Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014) p173.

Although marijuana does not make people sterile as some rumors have asserted, longer-term use of marijuana does have some effects on reproductive function. Marijuana suppresses the production of hormones, which translates to a decreased sperm count and may cause impotence in those consuming high doses over long periods of time  Woman who regularly use marijuana over a long period of time may experience irregular menstrual cycles, which may decrease the probability of conception (Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014) p181.

According to the authors of “Buzzed:The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy”, lethal overdose is virtually impossible (Kuhn, Swartzwelder, Wilson, p167).  If you find yourself anxious or fearful, the best solution is to remove yourself from the environment, people, or situation that is causing the stress.

As a life coach, finding any technique that helps in calming your central nervous system should be helpful. Some exercises I would suggest is taking a deep breathe, yoga stretches, listening to soothing music, being with a friend, etc.

Safety and Usage: Is marijuana addictive? Withdrawal symptoms, marijuana deaths and overdose

*Is marijuana addictive?  Can one develop a tolerance? How do you know if you are addicted?

The four principles of addiction from “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” are:

  • Addiction is the repetitive, compulsive use of a substance despite negative consequences to the user.
  • Addictive drugs initially activate circuits in the brain that responds to normal pleasure, like food and sex. Every brain has these circuits, so every human could potentially become addicted to a drug.
  • Drug taking persists for many reasons including changes in the brain, the desire to experience pleasure from the drug, and the desire to avoid the discomfort of withdrawal.
  • Many different factors in the life of an individual, such as family, history, personality, mental health, social and physical environment, and life experience, plays a role in the development of an addiction.

Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014): p 329

In the Tolerance, Dependence and Withdrawal section on marijuana covered in “Buzzed: The SFurther, heavy marijuana users do become dependent in the same ways that users of some other drugs do with cravings and  difficulty controlling the use of the drug, or have a psychological dependence.  However, the authors report that the numbers of people who have these addictions are relatively small.  (Kuhn, Swartzwelder, Wilson, p183)

*VIDEO: Can you get addicted to pot? How do you know if you are addicted? (

* Can you have withdrawal? What are withdrawal symptoms?

Withdrawal happens with chronic use. Some effects include agitation, irritability, restlessness, anxiety, difficulty eating, tremors and seizures. Others have reported experiencing insomnia, sweating and mild nausea. The jury is still out on whether THC has some effect on the brain’s reward system. While all the above is true, Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” cautions that we should not infer that marijuana is the equivalent to addictive qualities of narcotic drugs such as cocaine or heroin (Kuhn, Swartzwelder, Wilson, p183).

VIDEO: For any drug, how can you predict what your withdrawal symptoms may beWhat happens to your tolerance to pot over time? (

*Have there been any deaths with marijuana?

According to the authors of “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy, no one has ever died from an overdose (Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014): p 167)

However, the authors of the article noted reports of small children eating large doses of cannabis in cookies and going into a coma. Although there isn’t much research, there are also dangers with combining marijuana with other heart or blood pressure medications which suppresses the function of the immune system (Kuhn, Swartzwelder, Wilson, p167)

All in all, it’s important to remember that marijuana does place a greater workload on your heart. In addition, while under the influence, your judgment and reflexes are impaired which may result in automobile accidents and other dangerous mistakes.

* How dangerous is marijuana compared to other drugs out there?

*VIDEO: Dr. Scott Swartzwelder describes a continuum of drugs from most dangerous to least.

* How dangerous is marijuana to teens?

VIDEO:  8 minute video on research on effects of marijuana on teen brain development.

Side effects of marijuana: Does marijuana kill brain cells, marijuana benefits, Depression/Anxiety, Is marijuana bad for you?

*Can marijuana kill brain cells?

According to the authors of “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” :

At present the weight of the scientific evidence suggests that at the dose, and for the periods of time, that most people use marijuana, the answer is “no”.   Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014): p 177.

 *What are the effects to the brain short-term and long-term? (Stress, hippocampus, learning, memory)

The authors of Buzzed, who are from Duke University School of Medicine wrote extensively in their book “Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” about the effects of the brain that include several interesting studies that I would suggest reading. Listen to a quick summary from Dr. Scott Swartzweleder.

While people are high, they are significantly less able to store new information than when they aren’t high. In fact, the single most common and reproducible cognitive effect of marijuana is this interference with memory processing, specifically the ability to form new memories.  Marijuana appears to have residual effects on cognitive functions (including memory) for up to forty-eight hours.  Furthermore, a person who smokes marijuana every few days is probably never completely free of its effects on thinking and problem solving; living consistently in a somewhat compromised cognitive state.  Kuhn, Swartzwelder, Wilson, Buzzed, 4th ed. (2014) p 185

*VIDEO: How is the brain affected by pot? (

*What are potential health risks of taking marijuana (short-term and long-term)?

Buzzed: The Straight Facts About the Most Used and Abused Drugs from Alcohol to Ecstasy” mentions several studies with regard to health issues. Although marijuana does affect heart rate with increases of twenty to thirty beats per minute, there is no direct evidence that it will lead directly to a heart attack or heart disease (Kuhn, Swartzwelder, Wilson, p179). In terms of lungs, many of the toxic compounds such as tar, carbon monoxide, and cyanide are found in comparable levels in both tobacco and marijuana smoke. Benzopyrene, a carcinogen, has a great concentration in marijuana. However, there has been no definitive evidence that links marijuana smoking with lung cancer (Kuhn, Swartzwelder, Wilson, p180)

*VIDEO: What are potential health risks? What are the physical harm you can do from marijuana use?

Living and Using Marijuana: Driving and marijuana

*How is driving impaired when using marijuana?

Marijuana decreases your attention and concentration, which makes operating any kind of heavy machinery very dangerous.  As described by Dr. Scott Swartzwelder, marijuana also changes perception and sense of time, causes slower reflexes and easy distractibility..

* Video: When is it safe to drive after marijuana use?   Is there an equivalent that you can check to see if you are “ok” to go on the road?

Dr. Scott Swartzwelderwhat happens when you drive while you are stoned ( and

When is it safe to drive after smoking pot? Legal limits for smoking and driving (

About Professor H. Scott Swartzwelder

SCOTT SWARTZWELDER, PH.D., is a professor in the Psychiatry and Behavioral Sciences, Professor of Psychology and Neuroscience  at Duke University, Durham, North Carolina.  Professor of and Faculty Fellow of the Center for Child and Family Policy. Senior Research Career Scientist with the U.S. Dept. of Veterans Affairs.