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How Does Marijuana Work?

science of marijuana

The science behind medical cannabis is complicated. Why? The cannabis plant contains up to 150 cannabinoids, 220 terpenes/terpenoids, and 20 flavonoids, all of which have different effects when used independently or combined. This makes cannabis a very versatile medication but also challenging to figure out.

However, we know that cannabis is a “pharmacy in a plant,” meaning it can potentially treat a range of common conditions. Learn the science of marijuana and how the plant works in your body in our comprehensive guide. 

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The Endocannabinoid System

Before we delve into the science of marijuana, we first need to discuss a little about the human body, namely the endocannabinoid system (ECS). The body produces natural versions of tetrahydrocannabinol (THC) and cannabidiol (CBD), called endocannabinoids. 

When the body does not produce enough cannabinoids (clinical endocannabinoid deficiency), or if their production is dysregulated in some other way, inflammation can go haywire, leading to health problems. THC, CBD, and other cannabinoids in the cannabis plant help replace these lost cannabinoids and have anti-inflammatory effects. This is what makes marijuana medicine. 

Download Free Guide to the ECS

Cannabinoid Receptors

There are two main primary cannabinoid receptors:

  • CB1 receptors, which are mostly found in the brain, central nervous system (CNS), and peripheral organs and tissues.
  • CB2 receptors are found in the immune system, peripheral nervous system (PNS), brain, and gastrointestinal system.
The Endocannabinoid System (ECS). How THC moves along the ECS. Synaptic signaling.
The Endocannabinoid System (ECS). Synaptic signaling of THC across the presynapse and postsynapse.


There are two main endocannabinoids (cannabinoids the human body produces naturally):

  • Anandamide (AEA)
  • 2-Arachidonoylglycerol (2-AG)


The endocannabinoid anandamide targets CB1 receptors. THC is anandamide’s mimetic phytocannabinoid, meaning the two compounds have similar properties and behaviors. CB1 receptors were first cloned in 1990.

The enzyme that breaks down anandamide and THC is called fatty acid amide hydrolase (FAAH). Regular cannabis users who use THC-rich varieties have lower levels of FAAH, meaning more anandamide is available in the body, leading to pleasurable effects.


The endocannabinoid 2-Arachidonoylglycerol (2-AG) is active on both CB1 and CB2 receptors. CB2 receptors were first cloned in 1993. 

Like anandamide, 2-AG plays a pivotal role in pain management, immunity, and appetite. It is also the most abundant endocannabinoid found in the body. 

The Compounds in Cannabis

The naturally occurring compounds in cannabis give the plant its therapeutic properties. Among these compounds are phytocannabinoids, terpenes, and flavonoids. 


Phytocannabinoids are cannabinoids derived from the cannabis plant. There are six main or “big” cannabinoids, including:


THC is the primary psychoactive compound found in the cannabis plant and directly attaches itself to receptors (CB1 receptors) in the brain. THC is often the cannabinoid found in the highest concentrations in the cannabis plant.

THC is an effective painkiller and could also be useful as an anti-inflammatory, spasticity, antiemetic (nausea/vomiting prevention), appetite stimulant, and treatment for an overactive bladder. 

THC could be useful for treating chronic pain, neuropathic (nerve) pain, the side effects of chemotherapy, insomnia, nausea/vomiting, anxiety, tremors, and tics. THC could be beneficial for treating chronic pain, autoimmune disorders, cancer, nausea, multiple sclerosis (MS), Parkinson’s Disease, Alzheimer’s Disease, and insomnia.

Acidic cannabinoids are converted into their non-acidic form when they age and are exposed to heat. The acidic form of THC is tetrahydrocannabinolic acid (THCA). THCA converts into THC when it loses a carbon dioxide molecule from its chemical structure. This is called decarboxylation, which activates the cannabinoid.

Download Free Guide to THC


CBD is the second most prevalent cannabinoid in the cannabis plant, after THC. It accounts for up to 40% of the plant’s extract. CBD has a physiological effect on the body and can be used as a mood enhancer. While it is not psychoactive in the same way as THC (i.e., it’s not as intoxicating), CBD does have a non-typical form of psychoactivity.

Some say that CBD gives them a broadly relaxed feeling. Less “on-edge” and more emotionally “even.” This relaxing feeling, combined with CBD’s anti-inflammatory effects, could help it treat pain and insomnia.

CBD also calms down inflammation in the brain and nervous system, especially when combined with THC. This can make CBD useful for epilepsy, Parkinson’s disease, Alzheimer’s disease, multiple sclerosis (MS), and neuropathic (nerve) pain.

Minor Cannabinoids

Beyond THC and CBD, cannabis contains minor cannabinoids like THCV, CBG, CBN, and CBC. 


In low doses, tetrahydrocannabivarin (THCV) is not psychoactive, has an appetite-suppressing, energizing effect, and blocks THC. In high doses, THCV is psychoactive and combines with THC for even more significant psychoactive effects.

THCV can have the following effects:

  • Reducing appetite and reversing insulin resistance – low doses – useful for obesity and diabetes.
  • Energizing – low doses – useful for depression.
  • Antipsychotic – low doses.
  • Psychoactive – high doses – a more “clear-headed” and less sedative effect compared to THC, but still somewhat sedative in high doses.
  • Anti-inflammatory.


Cannabigerol (CBG) is sometimes referred to as the “parent cannabinoid,” as the plant converts cannabigerolic acid (CBGA, which is what CBG is before it is exposed to UV light and/or heat) into tetrahydrocannabinolic acid. 

CBG may counteract the psychoactive effects of THC. CBG does not make you feel “high” or “stoned.” However, CBG does still have a physiological impact. It could be said that CBG is more of a “non-intoxicating” cannabinoid than a non-psychoactive one.

CBG can boost anandamide without psychoactive effects, and it could be a great alternative or addition to THC. CBG may be very useful in the treatment of chronic pain, cancer, and superbugs like MRSA. Low doses of CBG can also beat nausea, but high doses could cause stomach upset.


Unlike many other cannabinoids, cannabinol (CBN) does not stem from cannabigerol (CBG). CBN is a metabolite of THC that is formed as cannabis ages. THC degrades into CBN over time and exposure to ultraviolet (UV) light.

CBN could be useful for the following:

  • Chronic Pain CBN is a mild painkiller and anti-inflammatory.
  • Anti-epileptic CBN’s slight sedative effects could be useful for the treatment of seizures and convulsions.
  • Appetite stimulant CBN’s slight affinity for CB1 receptors could help stimulate the appetite.
  • Antibacterial CBN could slow bacterial growth, making it useful for the treatment of superbugs like MRSA.
  • Insomnia CBN has sedative effects.


Cannabichromene (CBC) is the third most prominent cannabinoid found in the cannabis plant. The precursor to CBC is cannabichromene carboxylic acid (CBCA), cannabichromenic acid.

CBC is thought to be up to 10 times more potent than CBD for treating stress and anxiety and has significant anti-inflammatory, pain-reducing, antiviral, anti-tumor, and bone-growth-stimulating properties.


Terpenes are a class of hydrocarbon-based compounds that give cannabis its unique smell. You will also see the term terpenoids used. Terpenoids are a class of terpenes but are modified chemically in some way to act differently when ingested.

Cannabinoids and terpenes share the same chemical precursor, geranyl phosphate. This means that terpenes and cannabinoids are linked. Terpenes can control the amount of THC that crosses the blood-brain barrier (BBB) and can influence the way cannabinoids behave in other ways.

The cannabis plant contains many different terpenes, with some of the most prominent being alpha- & beta-pinene, limonene, linalool, myrcene, humulene, eucalyptol, trans-nerolidol, terpineol, delta-3 carene, and camphene. Another terpene, beta-caryophyllene, is also a cannabinoid as it targets CB2. Beta-caryophyllene is a dietary cannabinoid found in black pepper and could be useful in treating inflammation and addiction

The terpenes found in CBD and cannabis oil, and what they do.
The terpenes are found in cannabis and full-spectrum CBD (cannabidiol) oil.


Flavonoids are compounds in the cannabis plant that contribute to its smell and flavor. The cannabis plant contains up to 20 flavonoids. Cannflavins A, B, and C are of particular interest because they may be:

  • Neuroprotective
  • Antioxidants
  • Have anti-cancer properties in several animal models.
  • Cannflavin A has been the most studied of the cannflavins. Cannflavin A may interact with CBD and THC and may reduce inflammation.

Cannflavins are unique to the cannabis plant and give the plant its distinctive aroma.

How Cannabis Interacts with the Endocannabinoid System

Cannabis binds to receptors in the endocannabinoid system to exert different effects. Many of these effects are therapeutic. There is evidence that cannabis may interact with the ECS sufficiently to treat:

Other Factors That Influence How Marijuana Works

Marijuana may affect you differently depending on several factors. 


At once, the most basic and most important factor, dosage, strongly influences how cannabis makes you feel. Low doses are recommended for beginners, while experienced users can experiment with different CBD:THC ratios. But there are no hard and fast rules for the general population, and your doctor is best qualified to tell you which dosage to take. 

It is also important to note that cannabinoids have biphasic effects. This means that a different dose of the same cannabinoid can have other effects. For example, low doses of THCV are anti-psychoactive and appetite-curbing, as it is a CB1 receptor antagonist. At higher doses, THCV is psychoactive. 

With CBD, low doses are more energizing, while high doses can be sedative. THC can treat anxiety in low doses or prompt it in higher doses. CBG, meanwhile, can treat nausea in low doses but potentially cause it in higher doses.


Some strains contain more THC and are more psychoactive, while others have more CBD and don’t cause to get high. Sativa-dominant strains may make you feel energetic, while indica-rich strains may relax you. But these are generalizations, and each strain will affect each individual uniquely.

It is also a bit of a misnomer to call different cannabis varieties “strains,” as the plants are not necessarily chemically distinct from each other. It is, therefore, more accurate to call different cannabis types “chemical varieties” or “chemovars.” For specific types of cannabis with unique cannabinoid & terpene profiles made by a breeder, the term “cultivar” is often used.

Other Medications

Be careful if using cannabis while taking prescription medications. Many medications, such as blood thinners and tricyclic antidepressants (e.g., amitriptyline, doxepin), are not recommended for use with cannabis. Cannabis could affect the potency of your prescription medication, even rendering it ineffective. Other drugs, like alcohol, should also be avoided when using cannabis. Those taking prescription opioids or sedatives ought to taper their use with the aid of a medical professional if utilizing medical cannabis.

Body Chemistry

How much do you weigh? How old are you? What is the general state of your health? The answers to these questions all impact how cannabis affects you. Your body chemistry can also change from day to day, meaning that the same strain and dosage of cannabis will not always have the same effect on you. 

The Bottom Line

Cannabis has been shown in many scientific studies and increasing clinical trials to be therapeutic. The plant can treat symptoms as mild as minor scarring as serious as nausea and vomiting from chemotherapy. 

The doctors at Leafwell can help you apply for your medical marijuana card now. Connect with us and schedule a virtual consultation today.

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Frequently Asked Questions

Does marijuana affect everyone the same way?

No, marijuana affects everyone differently. Factors such as dosage, strain, other medications you are taking, and your body chemistry all impact how cannabis will affect you. Everyone has their unique endocannabinoid system (ECS).

Can you get addicted to marijuana?

Cannabis is not generally thought to be addictive in the same way as heroin or cocaine. You can, however, overconsume cannabis in one session or over a long period. Be conservative in your use of cannabis to maximize the health benefits and minimize any associated risks.

Cannabis Use Disorder (CUD) is thought to affect about 9 percent of users. However, unlike with opioids, alcohol, or sedatives, cannabis withdrawal is not potentially deadly.

Can marijuana harm the body instead of help it?

In extreme quantities or taken with medications that negatively interact, marijuana can be harmful. Care must also be taken if you suffer from some types of cancer. For example, those with estrogen-positive breast cancer may want to avoid high doses of THC. Those with testicular cancer may also want to be wary of using THC. The best way to use cannabis safely is to get a medical marijuana card with a properly dosed prescription from a physician.

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