Understanding Medical Cannabis (Marijuana)

Author: Marisa Healy, BSN, RN
Last Reviewed:

What is marijuana?

Marijuana is made up of the dried leaves and flowers of a plant called Cannabis. There are two main types (species) of plants used as medical marijuana: Sativa and Indica. In the U.S., Federal law prohibits the use of cannabis. However, many individual states have legalized cannabis or the chemicals found in cannabis, called cannabinoids and terpenes.

Many people think of marijuana or cannabis as a plant used to get “high.” However, it has been found that compounds in the plant can be changed or taken out to lessen or get rid of the psychoactive effects (“high”). We will review the compounds found in cannabis and how they can be used to help with many cancer symptoms and some medication side effects. 

Cannabis Plant Species

There are two kinds of species, or kinds, of cannabis: Sativa and Indica. In the past, these two species were thought to have many different effects on the body. The truth is that most cannabis is a hybrid (mix) of the two. Each kind can affect people differently based on their body’s biology and tolerance, along with the terpenes made by specific strains (discussed below). 

  • Sativa plants grow in moist areas and are tall and skinny with long, thin leaves. Sativa species were thought to be more uplifting and energizing.
  • Indica plants grow in very dry or arid areas and have a shorter, stubbier plant with wide leaves to catch moisture. Indica species were thought to be more relaxing and calming, some even sedating

What are Cannabinoids?

The cannabis plant has more than 110 chemical compounds called cannabinoids, with even more that we don’t know about yet. Of these, 2 have been the focus of most studies on medical use: THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol). These chemicals have effects on the body like medicines do. They can affect the central nervous system and the immune system in different ways:

  • THC is the part of cannabis that has psychoactive effects – it can produce a “high” feeling. It has been found to help with pain, nausea, and insomnia.
  • CBD is the part of cannabis that has been found to help with anxiety, inflammation, and pain. It has no psychoactive effects.

The Balance of CBD and THC

Cannabis strains are grown to have different amounts of THC and CBD to meet the different needs a person may have for cannabis. This is called the THC: CBD ratio. THC and CBD work better together than either does alone. In general, the products fit into 3 groups:

  • THC dominant: These strains have less CBD and can cause a strong “high,” sleepiness and anxiety. The degree of “high” can vary based on your tolerance. For this reason, it is often suggested to start with a low dose and work your way up.
  • CBD dominant: These strains have less THC than CBD, allowing you to have a clear head to maintain your normal roles & responsibilities. When there is more CBD than THC, you will likely not have any psychoactive change.
  • Balanced CBD and THC: These strains tend to have a slightly higher amount of either component, but are more balanced than the strains listed above. When there is a similar amount of CBD and THC, the CBD will cancel much of the psychoactive effects of the THC compound.

How do Cannabinoids work?

We have receptors throughout our body that make up the endocannabinoid system (ECS). This is one of the most widely spread receptor systems throughout our bodies. Everyone’s ECS is different. Our bodies naturally make “endocannabinoids” that work with the ECS receptors. The ECS system helps our body keep balance (called homeostasis). Cannabinoids that come from plants (like cannabis plants) are also able to work with these receptors.

The two major ECS receptors are CB1 and CB2 receptors. 

  • CB1 receptors are most commonly found in the nerve cells of the brain and spinal cord. It is these receptors that THC interacts with to cause its psychoactive effects or “high.” 
    • CB1 receptors can also be found in the spleen, GI tract, reproductive and urinary systems, endocrine system and white blood cells. The fact that these receptors are found in so many areas of the body explains why cannabinoids can be used for different things. 
    • CB2 receptors are commonly found in the immune and hematopoietic (blood cell) systems. They are also found in the brain to a lesser degree than CB1 receptors. 

What are Terpenes?

Terpenes are compounds or essential oils found in many plants and some insects. They cause some of the taste and smell of the object. Terpenes bind to receptors like cannabinoids, causing certain effects in the body, and can act directly on tissues and cells in the immune system. There are hundreds of terpenes, but a handful are more common. 

Many cannabis analysis labs list terpene content on product labels, allowing you to choose a strain based on the terpenes it has. The more common cannabis terpenes are Myrcene, Terpinolene, Limonene, Humulene, Pinene, Linalool, and Caryophyllene. 

  • Myrcene is the most common terpene in cannabis and is thought to have a calming effect. It tends to be stronger in the Indica strands. Myrcene is found in mangos, lemongrass, and thyme. It can be used as an antioxidant and anti-inflammatory. This makes it useful in treating pain caused by inflammation.
  • Terpinolene is thought to have energy and is common in the Sativa species. It may work as an antioxidant and antibacterial agent. It is found in plants such as lilac, nutmeg, and cumin.
  • Limonene is found in many citrus fruits, rosemary, juniper, and peppermint. It is thought to lift mood and relieve stress. It may work for anxiety, depression, and inflammation.
  • Humulene can be described as woody or earthy and is found in hops, sage, and cloves. It may work for inflammation, pain, and as an anti-bacterial.
  • Pinene is found in pine needles, rosemary, basil, parsley, and dill. It can promote alertness and memory retention, while also counteracting some of the THC effects. It may work as a bronchodilator, analgesic, anti-inflammatory, anxiolytic, and is gastroprotective.
  • Linalool, commonly found in lavender and birch bark, offers mood enhancement and can be sedative. It tends to be more common in the Indica species and may be used to treat anxiety, depression, insomnia, pain, inflammation, and neurodegenerative disorders.
  • Caryophyllene is used for pain, inflammation, anxiety, stress, depression, and ulcers. It may be helpful in opioid withdrawal symptoms as well. Caryophyllene is found in common kitchen spices such as black pepper, cloves, cinnamon, and oregano.

Terpenes seem to work together with cannabinoids to promote the unique effects of each compound. This is known as the “entourage effect.” Some studies have found that using one cannabinoid, without the entourage of compounds found in the cannabis strain it came from, leads to fewer benefits.

How is cannabis used in cancer care?

Cannabis products are most often used for symptom management in people with cancer. It may be used to help pain, nausea, anxiety, and insomnia, and can stimulate (rev up) the appetite when weight loss is a concern. Some of cannabis’ compounds are being studied for their ability to slow down or stop cancer cell growth, though research is needed to understand how it works and which products and cancer types will have the best results. 

How is cannabis taken?

Cannabis can be taken or used in its whole plant form (often the flowers or “buds” of the plant) or compounds taken from the plant (THC or CBD). It can be taken in 3 main ways: 

  • Inhalation (through smoke or vapor).
  • Consumption (by mouth).
  • Topically (through creams, lotions, ointments, etc). 

It is important to point out that different states have legalized different methods or products, so you may not have these options available where you live.

Inhalation of Cannabis

Cannabis can be smoked in a pipe, hookah, or rolled into a “joint” (rolled in cigarette paper) or “blunt” (rolled in tobacco paper). Cannabis can also be inhaled in vapor form – called vaporized. This is done using a vaporizer, which heats the product enough to release the cannabinoids but does not ignite or burn the product. Vaporization has shown to be a cleaner method of inhaling cannabis as there is no smoke or carcinogens being inhaled. There have been health concerns around vaping marijuana in the news, but it is important to remember these health problems happened using unregulated products that had other toxic ingredients.

There are many different types of vaporizers that use different cannabis forms, such as the bud of the plant, and an oil or wax/resin (also called shatter). These may be used by adding them to the vaporizer or may come in pre-filled cartridges that fit in the vaporizer. 

Vaporization tends to work more quickly than oral methods – in as little as 1 to 15 minutes. It often lasts 1-3 hours, which is shorter than ingested (swallowed) methods. During vaporization, CBD and THC are inhaled into the lungs along with other compounds. This can be a concern, particularly for people with lung disease or cancers affecting the lungs.

Taking Cannabis by Mouth

There are a few ways to take cannabis by mouth, such as tinctures, capsules, oils, and edibles. 

  • Tinctures are liquids that are mainly used sublingually, meaning it is placed under the tongue to sit for about 30 seconds. This lets it be quickly absorbed and can start working in 15-30 minutes. Sublingual cannabis tends to last about 2-4 hours in the body. A tincture can also be swallowed directly or placed in a liquid beverage, though this takes longer to work (30-90 minutes).
  • Oils can be used as a sublingual (under the tongue), can be swallowed, or taken in a capsule/softgel. 
  • Cannabis oils, tinctures, flower, or ingredients infused with cannabis (such as butter or vegetable oil) can be used to make foods or drinks that produce the effects of cannabis. These are called edibles. Consuming cannabis in this way will have an effect in about 30 to 90 minutes, but will offer the longest duration of action – 4 to 8 hours.

Using Topical Cannabis

Topical cannabis is made by heating the cannabis flower to activate the cannabinoids and making an extract from this. This can be made into a lotion, cream or ointment. These can provide pain relief to the area they are applied. The cannabinoids are not absorbed into the bloodstream, so there is no risk of psychoactive effects or getting high. Topical cannabis tends to work quickly – anywhere from 1 to 10 minutes and can last up to 5 hours. 

Another “topical” method is known as transdermal, such as through a patch placed on your skin. These compounds are absorbed into your bloodstream. THC is absorbed, so there is a risk of psychoactive effects. These are available as either THC alone or a balanced formula containing both THC and CBD.

How does cannabis from a dispensary differ from recreational marijuana?

A dispensary has trained staff to help you choose products. They can help you choose the right product and ratio of THC:CBD for your needs. Marijuana from a dispensary is highly regulated and labeled with ingredients and amounts so you can understand and be comfortable with what you are using. Recreational marijuana is not regulated. You cannot be sure what you are getting, if there are contaminants, or if it is safe. 

What about the CBD products I see in the mall/grocery store/etc.?

CBD products found in stores and online are made from the hemp plant, which contains less than 0.3% THC and will not cause any “high” effect. The main difference between hemp and marijuana is that hemp produces much less THC and does not have many of the other helpful compounds found in cannabis. For this reason, CBD oil from hemp may not have the same effects as CBD from cannabis. 

When purchasing CBD oil from a cannabis dispensary, you will need to look at the THC content. The staff in a shop can help you find how much THC is best for your needs. However, remember that every person’s body is different and it may take a little experimenting before you find the best product for your needs.

CBD and THC oils generally come in 3 types:

  • Full-spectrum– Has all the compounds found in the source product, such as THC, CBD, terpenes, and other cannabinoids.
  • Broad-spectrum– Has many of the compounds from the source plant, but THC is removed.
  • CBD isolate– Has only CBD with all other compounds removed.

How can I access cannabis?

Unfortunately, there is no one answer to this. Each state has its own laws and processes for gaining access for medical use. In a few states, cannabis is legal for all adults. In most states, you must have a health condition on that state’s list of conditions to qualify for medical cannabis. If you have a qualifying condition, you will need to get a medical marijuana card to visit a dispensary (the place cannabis products are sold), buy, and carry products. In some states, you are also able to grow small amounts of cannabis.

The first step is to visit a provider registered with your state who can recommend or certify you for medical cannabis use. In some states, this must be a doctor (MD or DO), while nurse practitioners (NPs) and physician’s assistants (PAs) can do so in other states. You can learn more about finding a provider in the links at the end of this article. Since marijuana is federally illegal at this time, they cannot write a prescription as they do with other medications. Instead, the provider recommends marijuana for your situation and may provide some guidance as to the type that might benefit you most. For instance, a person with breathing problems may be advised to not use vaporized cannabis. You will then need to follow your state’s process for obtaining your card.

How can I learn more?

There are many resources for information about medical marijuana and CBD. Regulations differ from state to state, and you must abide by the laws in your state. Many states do not allow reciprocity, meaning you cannot use your card to purchase medicinal cannabis outside of the state where you are registered. There may also be legal concerns with traveling across state lines with products.

If you are interested in learning more, the list below can help you get started in your research: 


Birdsall, S. M., Birdsall, T. C., & Tims, L. A. (2016). The use of medical marijuana in cancer. Current oncology reports18(7), 40.Cannabis and Cannabinoids (PDQ®)–Health Professional Version. (2011, March 16). [PdqCancerInfoSummary]. National Cancer Institute. https://www.cancer.gov/about-cancer/treatment/cam/hp/cannabis-pdqClark, C. S. (2018). Medical Cannabis: The oncology nurse's role in patient education about the effects of marijuana on cancer palliation. Clinical journal of oncology nursing22(1).DeMarco, C. (n.d.). CBD oil and cancer: 9 things to know. Retrieved January 8, 2020, from https://www.mdanderson.org/publications/cancerwise/2019/09/cbd-oil-and-cancer--9-things-to-know.htmlKramer, J. L. (2015). Medical marijuana for cancer. CA: a cancer journal for clinicians65(2), 109-122.State Medical Marijuana Laws. (n.d.). Retrieved January 8, 2020, from https://www.ncsl.org/research/health/state-medical-marijuana-laws.aspx#1Tuesday, M. B., August 6, & 2019. (n.d.). What Is CBD Oil, and Can It Help People with Cancer? Memorial Sloan Kettering Cancer Center. Retrieved January 8, 2020, from https://www.mskcc.org/blog/what-cbd-oil-and-can-it-help-people



November 12, 2015

An Introduction to Cannabis

by The 4Wholeness Team


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