Marijuana: Benefits, Risks, Preparation And Use


Marijuana: Benefits, Risks, Preparation And Use


Marijuana is the phrase used to describe the dried leaves, stems, seeds, or flowers of the marijuana plant, Cannabis sativa, a plant with origins in the ancient world.

Marijuana is one of three main forms of cannabis. Medical marijuana refers to using dried plant parts or extracts to treat certain medical conditions or relieve disease symptoms.

The resins from the cannabis plant that produce effects on the brain, mood, or consciousness are called cannabinoids.

Cannabis extracts make up the most widely used illicit drug in the United States. Illicit refers to the risk of addiction to the drug and the fact it is illegal.

Marijuana can be smoked in hand-rolled cigarettes, special pipes, or bongs (water pipes). The drug also can be added to foods or as a brewed tea to drink.

Active ingredients also can be added to a salve, similar to lip balm, that can be applied to the skin.

The intoxicant effect or high from marijuana is in an active ingredient called delta-9-tetrahydro-cannabinol, or THC.

The compound called cannabidiol (CBD) does not have the intoxicating effects of THC.


Recreational use of marijuana involves no medical professional or reason for use, other personal choices.

People who use marijuana notice rapid effects when they smoke marijuana as the THC moves from the lungs to their bloodstream.

The compound travels to the brain through the blood. The effects are nearly immediate when marijuana is smoked and take up to one hour if marijuana is eaten.

In general, people smoke marijuana recreationally to get high, often defined as a sense of relaxation and mild euphoria or joy.

Medical marijuana, on the other hand, is used to relieve symptoms related to medical conditions, diseases, or treatment side effects.

For example, medical marijuana has been used to help people with nausea and pain and symptoms relating to dementia, heart disease, Parkinson’s disease, and HIV/AIDS.


There are over 100 types of cannabinoids and other substances in cannabis.

CBD has been shown to relieve pain and ease inflammation. There also is some evidence CBD can lessen anxiety and help regulate mood and sleep.

A 2017 report from the National Academy of Sciences stated there was serious evidence cannabis being effective in treating chronic pain in adults and helping people with multiple sclerosis or similar diseases ease symptoms.

Strong evidence also supported the use of oral cannabinoids to ease nausea and vomiting in patients undergoing chemotherapy.

There was some evidence in the report that medical marijuana could improve sleep in people who had trouble sleeping because of problems such as apnea or conditions causing chronic pain.

Slight evidence also was found that medical marijuana could increase appetite in people with HIV/AIDS, improve symptoms of Tourette’s syndrome, and relieve symptoms of social anxiety and posttraumatic stress disorder.

Many other findings were not conclusive until more research is completed.

There is some evidence that increasing the use of medical marijuana for pain in patients can help lead to fewer addictions to opioids, which are narcotic and highly addictive pain killers.

Studying the health effects of medical marijuana presents special challenges, including legal restrictions and inconsistent concentrations of cannabinoid chemicals extracted from plants.

Studies eventually should lead to a better understanding of using medical marijuana as safely and effectively as possible.


Among the harms of medical marijuana are possible addiction and impaired thinking.

Teens who use marijuana regularly can demonstrate lower verbal abilities, impaired thinking, and even decreases in total IQ years later.

In the short term, smoking marijuana can make a person drowsy and less coordinated, impairing driving or performing work tasks.

Long-term effects could include a higher risk of lung diseases such as lung cancer, decreased memory or ability to learn, and lower motivation to study, work, or concentrate on difficult tasks.

Parents and physicians should carefully supervise children and teens who are prescribed medical marijuana.

Symptoms of marijuana use include being dizzy, having red or bloodshot eyes, and forgetting recent events. People generally report that time seems to slow down, and their appetite increases while high.

The effects depend on the amount used, the type of compounds in the marijuana, and whether a person smokes, drinks, or eats the marijuana.


Despite the increasing public acceptance of marijuana, especially medical marijuana, the drug and other cannabinoids are illegal in the United States except for designated research.

However, many states have introduced or passed laws making medical marijuana legal with restrictions and even making limited recreational use legal in nine states.

There typically are restrictions on the legal amount allowed, the age that can purchase, and where marijuana products can be sold.

As of November 2018, 33 states, plus the District of Columbia, Guam, and Puerto Rico had approved public medical marijuana programs.

The laws vary in restrictions on uses but generally require prescriptions from medical providers and designated dosages.

Some countries also have approved medical and recreational use of marijuana. For example, Canada made medical marijuana use legal and then became the second country to pass to allow nationwide sales.

Whether medical marijuana should be legalized and enforcement of federal laws is affected by political and public opinion.


Marijuana can be ingested by smoking or vaporization (heating without combustion).

Smoking or vaporizing gives a more rapid onset of action than other routes, usually within seconds to minutes, and can last from one to three hours.

The dehydrated herb can also be prepared for eating in cookies or other baked goods.

When eaten, the cannabinoids in marijuana have a slower onset of action, sometimes as long as two hours, but the effects can last as long as five to eight hours.

A few drops of cannabis tincture placed under the tongue become effective within 20 minutes.

The essential oil of marijuana consists of beta-caryophyllenes, humules, caryophyllene oxide, alpha-pinenes, beta-pinenes, limonene, myrcene, and beta-ocimene.

The oil expressed from the seeds is used for massage and in making salves used to relieve muscle strain. The duration of action in salves has not been extensively studied.

There are no standard guidelines for dosage ranges as of 2020 because the strength of a specific marijuana preparation is highly dependent on such factors like the growing and harvesting condition of the plant and the specific plant parts (leaves, buds, or flowers) isolated for use.


Marijuana remained a Schedule I drug as of 2020, and its use has been restricted by federal law since 1937.

Penalties include fines and imprisonment. In general, however, the Justice Department does not enforce federal law in states that have legalized or decriminalized cannabis.

Several advocacy organizations, including the American Legion, the American Medical Association, and the American Academy of Family Physicians, have called on the DEA to review the Schedule I classification and reschedule cannabis to facilitate research into its possible benefits.

The study has proven that cannabis operates by increasing heart frequency by 40 beats in 1 minute. 

Research reported by the American Heart Association in February 2000 confirmed that smoking marijuana might speed up a heart stroke in persons with pre-existing heart issues. 

One hour afterward smoking marijuana, the prospect of acquiring a heart attack is almost 5 times higher than if the individual had not smoked, according to the research.

There have been two reported deaths, one in New Jersey in 2017 and another in Louisiana in 2019. The medical examiners determined were caused by heart arrhythmias (abnormal heart rhythms) precipitated by smoking marijuana.

Marijuana practice has also been linked to an increased risk of motor vehicle accidents.

Although there is a test for THC in a driver’s blood, the THC level (limited by several states to no more than 5 nanograms per milliliter of blood) does not measure the extent of impairment in the same way as the blood alcohol content (BAC) test measures impairment caused by alcohol ingestion.

The logic for this difference is that the metabolism of THC varies widely between frequent and infrequent users; besides, different strains of cannabis vary considerably in potency.

It is known, however, that THC impairs a driver’s short-term memory, reaction time, and judgment.

Combining marijuana use with alcohol consumption multiplies the effects of both drugs on a driver; a 2009 collision on the Taconic State Parkway cost the lives of eight people when a driver impaired by both vodka and marijuana drove the wrong way for several miles on the parkway.

About 400 deaths per year on U.S. highways are attributed to drivers impaired by marijuana alone.

The National Highway Traffic Safety Administration (NHTSA) has a website titled “Feel Different Drive Different” ( ) about the risks of driving under the influence of marijuana, which is illegal in all 50 states, including those that have legalized the recreational use of marijuana.

A further health consideration is an impact that marijuana smoking has on the lungs.

 Cannabis exhaust carries more tars and other particulate matter than tobacco smoke.

Although researchers note that it is not easy to separate the effects of marijuana smoke from tobacco smoke because many smokers use both cigarettes and marijuana, heavy marijuana use is connected with an elevated risk of chronic obstructive pulmonary disease (COPD).

Also, a group of Canadian researchers found that long-term smokers who use tobacco and marijuana suffer a steeper decline in lung function than those who smoke only tobacco.

The connection between marijuana use and lung cancer was unclear as of 2020.

Even though marijuana is much less likely than certain other drugs to induce dependence Syndrome, hard users can suffer a withdrawal syndrome characterized by anxiety, irritability, chills, and muscle cramps if they stop use abruptly.

Much more seriously, marijuana has been linked to the onset or worsening of certain psychiatric conditions, including panic disorder, schizophrenia, and depersonalization disorder. Persons diagnosed with or at risk of these conditions should not use marijuana.

Considerations for seniors

Marijuana does not appear on the Beers List, also called the Beers Criteria for Potentially Inappropriate Medication (PIM) Use in Older Adults.

This list of drugs was first drawn up in 1991 by geriatrician Mark Beers and revised several times by the American Geriatrics Society (AGS), most recently in 2019.

There are, however, several reasons why doctors are cautious in recommending medical marijuana to seniors:

  • Changes in the body’s metabolism of drugs. The aging body takes longer to metabolize and clear drugs, which means that the longer-acting a drug, the more likely it is to remain and accumulate in the body.
  • Changes in cognition. Geriatricians who have studied the effects of cannabis in seniors recommend evaluating the patient’s psychiatric and substance abuse history and screening the patient for signs of dementia. It was not known as of 2020 whether marijuana interacts with drugs given to treat dementia.
  • The decline in muscular strength, reaction time, and coordination. Older adults should be cautioned not to drive for at least six hours after vaping or smoking and at least nine hours after consuming baked goods made with marijuana.
  • Polypharmacy. Polypharmacy is the medical term for the concurrent use of several drugs by the same patient. Hence older adults are more likely than younger people to take several prescription medications for such age-related complaints as arthritis, glaucoma, heart disease, high blood pressure, cancer, and type 2 diabetes; the risk of interactions between medications prescribed conditions and marijuana is increased.
  • Higher rates of depression and suicide. Older adults are at increased risk of emotional depression and potential suicide as a result of the losses associated with aging: bereavement following the deaths of loved ones; loss of physical strength and agility; onset of chronic health problems, particularly liver and kidney disorders; social isolation; loss of purpose following retirement from work; and financial difficulties. They are hence at increased risk of developing a substance use disorder with cannabis.
  • Generational characteristics of older adults. The Baby Boom generation is the initial generation of older adults to have developed some familiarity with marijuana in their younger years; people in this group are likely to have fewer reservations about the medical uses of marijuana than earlier generations. According to the National Survey of Drug Use and Health (NSDUH), the scale of adults aged 50 to 64 who reported cannabis use in the past year from 2002 to 2014 more than tripled, from 2.9% to 9.0%. This percentage has likely increased over the past half-decade. The most commonly reported reasons for using medical marijuana in this age group are musculoskeletal disorders and chronic pain.


Side effects of marijuana used for medical purposes include dizziness, dry mouth, nausea, euphoria, confusion, drowsiness, and hallucinations.

Extreme use of marijuana is associated with nausea, vomiting, and abdominal pain, a triad called cannabinoid hyperemesis syndrome (CHS).

Other side effects that have been reported with the recreational and medical use of marijuana are skin rash, dry eyes, constipation, blurred vision, tooth discoloration, flushing, low blood pressure, high blood pressure, panic attacks, paranoia, fatigue, loss of balance, physical or psychological dependence, and withdrawal symptoms.


Marijuana interacts with a wide range of other drugs. Pimozide (Orap), an antipsychotic agent, is one drug that should never be taken together with marijuana.

Drugs that should not be used with marijuana if an alternative is available include erythromycin, several statins, ergotamine (a drug used to treat migraines), and immunosuppressants everolimus, and sirolimus, and thioridazine (an antipsychotic).

Seniors who take insulin for diabetes management or blood pressure medications may need to have dosage adjustments in these drugs if they use recreational marijuana.

There are an additional 267 drugs that require close monitoring if used with marijuana; the complete list can be seen at /drug/cannabis-ganja-marijuana-343687#3.




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American Psychiatric Association, 800 Maine Ave. SW, Ste. 900, Washington, DC 20024, (202) 559-3900,, .

American Society of Health-System Pharmacists (ASHP), 4500 East-West Hwy., Ste. 900, Bethesda, MD 20814, (866) 279-0681,

National Institute on Drug Abuse (NIDA), 6001 Executive Blvd., Rm. 5213, MSC 9561, Bethesda, MD 20892, (800) 662-4357 (national drug abuse helpline), (301) 443-1124, , .

U.S. Drug Enforcement Administration (DEA), 600-700 Army-Navy Dr., Arlington, VA 22202, (202) 307-1000,

U.S. Food and Drug Administration (FDA), 10903 New Hampshire Ave., Silver Spring, MD 20993, (888) 463-6332,