what are the side effects of medical marijuana


What Is Medical Marijuana?

Medical marijuana, also known as cannabis, is an herbal medication made from the dried buds and leaves of a type of cannabis plant.

The active ingredients in marijuana are known as cannabinoids, which are naturally occurring compounds that many plants and animals make (your body also manufactures some cannabinoid compounds).

Cannabinoids play an important role in thinking, memory, and sensory perception, according to the National Institute on Drug Abuse (NIDA).

Marijuana contains hundreds of cannabinoids, including delta-9-tetrahydrocannabinol, or THC, believed to be the most important and active cannabinoid in marijuana.

THC alters brain signals and affects mood, pain perception, appetite, and inflammation.

Marijuana also contains cannabidiol, or CBD.

In addition to treating pain and inflammation, some studies suggest CBD may be useful in treating seizures, epilepsy, mental illness, and addiction.

Other studies suggest that marijuana could be useful in managing health problems such as:

  • Severe weight loss
  • Nausea and vomiting (caused, for example, by chemotherapy)
  • Chronic pain
  • Spasticity from multiple sclerosis (MS)
  • Anxiety disorders
  • Insomnia and other sleep disorders
  • Anorexia
  • Arthritis
  • Migraines
  • Parkinson’s disease
  • Alzheimer’s disease
  • Glaucoma

Medical marijuana in herbal form differs from man-made forms of cannabis, such as Marinol (dronabinol), which also have medical uses.

Marijuana Benefits and Use

The use of marijuana for medical purposes dates back at least 3,000 years.

By the 1800s, doctors were routinely using marijuana to treat pain, inflammation, and convulsions.

But the use of medical marijuana to treat health problems is still the subject of ongoing debate.

In 1906, the U.S. Congress passed the Pure Food and Drug Act, which required that over-the-counter preparations containing cannabis be labeled as such.

The safety of marijuana was eventually called into question, and in the early 1930s the Uniform State Narcotic Act encouraged states to regulate it as a narcotic.

Under the Controlled Substances Act of 1970, marijuana was classified as a Schedule I drug. That means it was considered to have no medical use and a high risk for abuse, which has stymied research into its potential benefits.

Even so, marijuana was given to certain patients on an individual basis between 1978 and 1992 under the Compassionate Use Investigational New Drug program.

Since then, scientists have continued their efforts to study how marijuana affects the brain and other parts of the body.

At one time, the American Medical Association (AMA) opposed any regulation of cannabis that would limit research into its medical benefits.

The Food and Drug Administration (FDA) has not yet approved medical uses for marijuana.

But the agency has approved a drug that contains a synthetic version of a substance found in marijuana, along with another medicine that contains a substance that acts similarly to compounds found in the plant.

Marijuana Strains

The type of medical marijuana you take will probably depend on your illness and symptoms.

There’s some controversy about the physical effects of each kind of marijuana. There are three main plants, which are:

Sativa These plants are tall and have long, narrow leaves. They’re usually grown outdoors. Some people believe sativa plants have more of a stimulant effect. This type of marijuana is sometimes used during the day because it’s known to increase energy and alertness.

Indica These plants are short, have wider leaves, and are typically grown indoors. Indica plants are thought to be sedatives and have a more calming effect when taken medicinally. For this reason, this type of marijuana is sometimes taken at night.

Hybrid A hybrid is a combination both sativa and indica plants, and contains characteristics of both.

Taking Marijuana for Medical Purposes

Medical marijuana can be consumed by:

Inhaling smoke With this method, you pack a small amount of dried cannabis into a pipe or rolling paper.

Then, you light it and inhale the smoke from the mouthpiece of the device. While it’s inexpensive and easy, smoking marijuana could be harmful to your lungs because many other toxins are produced by the creation of smoke.

Using a vaporizer To vaporize marijuana, place a small amount of dried cannabis or cannabis extract into a vaporizer machine and inhale it.

This option allows you to inhale a vapor instead of smoke.

Consuming edibles You can infuse cannabis into butter or oil and cook it in different foods.

Medicinal marijuana is often mixed into brownies, cookies, lollipops, ice cream, gummy bears, chocolate bars, and other foods.

Consuming cannabis this way is a popular alternative to inhaling it, though some experts have cautioned that the potency of edibles varies immensely, and can cause strong side effects that last for hours.

In a 2015 report, the Centers for Disease Control and Prevention (CDC) noted that “because absorption is slower [with edibles], the onset of effects is delayed … and duration of intoxication is longer when THC is ingested compared with when it is smoked.”

Using tinctures or sprays A tincture is a concentrated form of medical marijuana that’s often mixed with alcohol, glycerin, or medium-chain triglyceride (MCT) oil (found in coconut oil).

You can squirt or spray the solution under your tongue. It can also be mixed with water or other beverages. A downside to using this method is that it can be expensive.

Wearing a dermal patch A small patch can deliver marijuana through the skin. It’s most often worn on the wrist, foot, or ankle. One dose can last up to eight hours.

Applying other topical products Salves, ointments, lotions, oils, and sprays are all used for applying medical marijuana. These topical options typically don’t cause a “high.”

Medical vs. Recreational Usage

Marijuana is taken for medical purposes to ease symptoms associated with different illnesses.

But it’s also used for recreational purposes to alter a person’s state of consciousness and achieve a “high.”

According to the World Health Organization (WHO), marijuana is the most popular recreational drug used in the world.

Marijuana Legalization

The use of marijuana is illegal in the United States under federal law.

But the federal government allows states to pass laws that decriminalize recreational or medicinal use of the drug if the state has a regulation system in place.

California became the first state to allow the use of medical marijuana in 1996.

According to the National Conference of State Legislators (NCSL), 24 states and the District of Columbia currently allow for comprehensive public medical marijuana programs.

Several other states have approved “limited access” laws.

The NCSL maintains an up-to-date list of the states that have enacted medical marijuana laws.

Marijuana Warnings

One reason medical marijuana use remains controversial is that the amount of THC in each cannabis plant is variable and depends on how it was grown, prepared, and stored.

The more THC a plant has, the stronger its effects.

Marijuana also contains hundreds of other chemicals, the amounts of which can vary from plant to plant.

Using medical marijuana can impair your ability to drive, operate machinery, or perform any activity that requires you to be alert.

Before you use medical marijuana, it’s important to talk with your doctor about any medical conditions you have. You should also talk to your doctor about your history of alcohol and drug use.

After you smoke marijuana, your heart rate can increase by 20 to 100 percent for up to three hours.

Research suggests this effect can increase the risk for heart attack in the first hour after using the drug. This risk could be higher for people who are older or have existing heart disease.

Research also suggests that use of the drug may increase the risk of schizophrenia in people who are vulnerable to it.

Using marijuana can lead to dependency on the drug. An estimated 1 in 11 marijuana users will become addicted to the drug, according to NIDA.

The number goes up to about one in six among people who start using marijuana as teenagers.

There’s increasing evidence that marijuana may be harmful for adolescents.

Those who start using marijuana at a young age may be at greater risk for long-term or permanent effects on thinking and memory.

They may also be at greater risk for developing psychosis later in life.

People who smoke marijuana are at greater risk for chronic bronchitis (a form of chronic obstructive pulmonary disease, or COPD) and infection, though there’s no evidence linking the drug to lung cancer.

Marijuana and Pregnancy

Tell your doctor if you’re pregnant, might become pregnant, or are breastfeeding before using marijuana.

Children whose mothers used marijuana during pregnancy are at greater risk for difficulties with attention, memory, and problem-solving later in childhood.

Marijuana can be passed to infants through a mother’s breast milk. The drug can also affect the quality of a woman’s breast milk and how much she’s able to produce.

Marijuana Side Effects

Marijuana targets parts of the brain involved in pleasure, memory, concentration, and coordination. Because of this, it may affect how you think and feel.

Users of medical marijuana may experience the following side effects:

  • Changes in mood
  • Lack of coordination
  • Trouble thinking and solving problems
  • Increased appetite
  • Difficulty concentrating
  • Urinary retention
  • Constipation
  • Slurred speech
  • Dizziness
  • Red eyes
  • Dry mouth and throat
  • Impaired judgment
  • Slower reaction time
  • Lethargy

Tell your doctor if you experience any of these side effects.

If you have more serious side effects, stop using medical marijuana and call your doctor right away.

More serious side effects include:

  • Feelings of anxiety or paranoia
  • Increased heart rate
  • Depression
  • Problems with memory and learning

When smoking marijuana, users inhale up to five times more tar and absorb up to five times more carbon monoxide than tobacco smokers.

Smoking marijuana can also cause some of the same problems as tobacco, such as:

  • Phlegm and mucus production
  • Coughing
  • Trouble breathing
  • Upper respiratory infections

Those who are addicted to marijuana and stop using it may experience:

  • Trouble sleeping
  • Irritability
  • Hot flashes
  • Nausea

Marijuana Interactions

Always tell your doctor about any drugs you’re taking.

This includes other prescription drugs, over-the-counter (OTC) drugs, and dietary supplements that may interact with marijuana and cause problems.

Certain drugs are known to interact with marijuana. For instance:

  • Cocaine and amphetamines may worsen high blood pressure, increase heart rate, and damage the heart muscle.
  • Drugs that suppress the central nervous system, such as barbiturates, benzodiazepines, opioids, muscle relaxants, and antihistamines, could interact with medical marijuana. These are drugs used to treat seizures, pain, depression, cough and colds, sleep issues, and anxiety. Using medical marijuana while taking these medications could intensify their effects on the central nervous system and cause increased sleepiness.

Marijuana and Alcohol

Marijuana targets areas of the brain involved in memory and concentration, and can affect movement, coordination, and reaction time.

Even a moderate dose of marijuana can impair your ability to drive, operate machinery, or perform any activity that requires you to be alert.

These effects can increase dramatically if you combine marijuana with alcohol.

Marijuana Dosage

Because people using marijuana for medical purposes may smoke it or consume it in foods or teas, it’s hard to pinpoint precise doses.

Medical marijuana users often regulate their own dosing and determine how much they need to produce the desired effect, which depends on the needs of individual patients and their tolerance of the drug’s side effects.

The clinical response to marijuana is more rapid when it’s inhaled by smoking than when it’s ingested in edibles, since marijuana quickly enters the bloodstream after inhalation.

The effects may begin within minutes, peak within 30 minutes, and last for two to five hours.

In some cases, the effects on attention or specific behaviors can last up to 24 hours. When the drug is ingested in food or tea, it’s metabolized in the liver and absorbed by the body more slowly.

The strength and amount of marijuana needed to produce the desired effect depends on how much THC the marijuana contains.

The average concentration of THC in marijuana ranges from 1 to 5 percent. Sinsemilla, derived from the unpollinated female cannabis plant, may have THC concentrations of up to 17 percent.

Marijuana Overdose

It’s unlikely that you would overdose on marijuana, but high doses – especially from consuming edible marijuana – can cause a temporary psychotic reaction.

Some people may also experience intense paranoia, panic attacks, or extreme anxiety. Others may have hallucinations.

People who use marijuana long-term or frequently may experience impaired thinking or attention, even after not using the drug for an extended period of time.

Missed Dose of Marijuana

There’s no specified dosing or timing for use of medical marijuana.

Doses vary from person to person and are based on symptoms.

The best advice is to follow your doctor’s direction and use medical marijuana only when and as needed.

By Everyday Health Staff | Medically Reviewed by Robert Jasmer, MD

Latest Update: 2016-05-18
Copyright © 2014 Everyday Health Media, LLC

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Medical marijuana, also known as cannabis, is an herbal medication made from the dried buds and leaves of a type of cannabis plant.

Medical Marijuana (Cannabis)

  • What Is
    • What Is Marijuana and How Does It Work?
  • Side Effects
    • What Are Side Effects Associated with Using Marijuana?
  • Drug Interactions
    • What Other Drugs Interact with Marijuana?
  • Warning and Precautions
    • What Are Warnings and Precautions for Marijuana?
Brand Name: Cannabis, Ganja, Hash, Hashish, Hemp, Mary Jane, Pot, Reefer, Weed
Generic Name: marijuana
Drug Class: Analgesics, Herbals

What Is Marijuana and How Does It Work?

Tetrahydrocannabinol (THC), a component of marijuana, acts both centrally and peripherally on endogenous cannabinoid receptors. Activation of cannabinoid receptors affects serotonin release, increases catecholamines, inhibits parasympathetic activity and inhibits prostaglandin biosynthesis.

Marijuana can be used to decrease intraocular pressure, analgesia, anti-vomiting (antiemetic) effects and as an appetite stimulant.

Marijuana is available under the following different brand names: Cannabis, Ganja, Hash, Hashish, Hemp, Mary Jane, Pot, Reefer, and Weed.

The United States (U.S.) Drug Enforcement Administration (DEA) classifies marijuana as a Schedule 1 substance under the Controlled Substances Act (CSA). Schedule I drugs are recognized as having a high potential for abuse with insufficient evidence for safety and efficacy with no currently accepted medical use for treatment in the U.S.

Marijuana is not approved by the U.S. Food and Drug Administration (FDA) for medical use in the U.S. and remains classified as an illicit drug by the DEA. However, several states have adopted individual State Medical Marijuana Laws including: Alaska, California, Colorado, Hawaii, Maine, Maryland, Michigan, Montana, Nevada, New Mexico, Oregon, Rhode Island, Washington, and Vermont.

In October of 2009 the U.S. Justice Department announced that it will no longer enforce federal drug laws on persons who use marijuana for medicinal purposes or their sanctioned suppliers, as long as state laws are followed.

Dosages of Marijuana Should Be Given As Follows:

  • Tincture: 5-15 drops or 1-3 drops of fluid extract.
  • 1-3 grains (65-195mg) cannabis for smoking, potency highly variable.
  • Drug deteriorates rapidly
  • Treatment of HIV-associated wasting syndrome.
Dosage Considerations

Dosing of marijuana preparations is highly dependent on a variety of factors, including growing and harvesting conditions, plant parts isolated.


What Are Side Effects Associated with Using Marijuana?

Side effects associated with use of marijuana, includes the following:
  • Tolerance
  • Psychological or physical dependence
  • Withdrawal symptoms
  • Altered senses
  • Dizziness
  • Drowsiness (somnolence)
  • Fatigue
  • Reduced coordination
  • Cognitive impairment
  • Impaired balance
  • Euphoria
  • Paranoia
  • Hallucinations
  • Mood alterations
  • Panic
  • Anxiety
  • Low blood pressure (hypotension)
  • High blood pressure (hypertension)
  • Rapid heart rate (tachycardia)
  • Flushing
  • Fainting (syncope)
  • Dry mouth (xerostomia)
  • Nausea
  • Vomiting
  • Distortion of taste (dysgeusia)
  • Tooth discoloration
  • Loss of appetite
  • Increased appetite
  • Oral thrush
  • Diarrhea
  • Constipation
  • Urinary retention
  • Skinrash
  • Dry eyes
  • Blurred vision
  • Cough
  • Sore throat (pharyngitis)

What Other Drugs Interact with Marijuana?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Drug Interactions

May potentiate CNS depression w/ concomitant use with CNS depressants (e.g., barbiturates, ethanol, anxiolytics, sedatives, and hypnotics, sedating H1-blockers, SSRIs, and TCAs).

Use of marijuana with sedating anticholinergics may result in additive tachycardia and drowsiness.

Cannabidiol, an inactive constituent of cannabis, may weakly inhibit cytochrome P450 enzymes (CYP1A2, 2C19, 2D6, & 3A4).

Cannabis is also a minor substrate for CYP2C9, 2C19, 2D6, 3A4.

Severe interactions of marijuana include:

  • Astemizole
  • Cisapride
  • Pimozide
  • Terfenadine

Marijuana has serious interactions with at least 21 different drugs.

Marijuana has moderate interactions with at least 286 different drugs.

Marijuana has mild interactions with at least 84 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Marijuana?


This medication contains marijuana. Do not take cannabis, ganja, hash, hashish, hemp, Mary Jane, pot, reefer, or weed, if you are allergic to marijuana or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

  • Hypersensitivity
  • Co-administration with dronabinol (Cannabis derivative)
Effects of Drug Abuse

Effects associated with use of marijuana, includes the following conditions: tolerance, psychological or physical dependence, withdrawal symptoms, altered sensorium, dizziness, drowsiness (somnolence), fatigue, reduced coordination, cognitive, impairment, impaired balance, euphoria, paranoia, hallucinations, mood alterations, panic, anxiety, low blood pressure (hypotension), high blood pressure (hypertension), rapid heart rate (tachycardia), flushing, fainting (syncope), dry mouth (xerostomia), nausea, vomiting, distortion of taste (dysgeusia), tooth discoloration, anorexia, increased appetite, oral candidiasis, diarrhea, constipation, urinary retention, skin rash, dry eyes, blurred vision, allergy, cough and sore throat (pharyngitis).


Use caution if there is a history of substance abuse or mental illness, hepatic disease, cardiovascular disease, seizure disorder, in use with geriatric patients or when operating machinery or driving. Non-pharmaceutical preparations may be contaminated with fungus, which may be hazardous to patients with compromised immune systems.

Pregnancy and Lactation

There is insufficient data regarding safety to the fetus in pregnancy, therefore avoid use in pregnancy.

THC found in Marijuana is reported to be concentrated and is secreted into breast milk, therefore avoid use when lactating.

Medical Marijuana (Cannabis) What Is What Is Marijuana and How Does It Work? Side Effects What Are Side Effects Associated with Using Marijuana? Drug