cbd oil side effects

CBD Oil Side Effects: Ask a Pharmacist

CBD Oil Side Effects

As people become more familiar with legal hemp plant products like CBD oil, they naturally ask good follow-up questions. One frequently asked question from people new to CBD is, “Does CBD have side effects?” This is similar to the question, “Will CBD get me high?” Because if CBD comes from the same plant as THC, the Cannabis sativa plant, then it’s logical to ask if it has a similar effect. But that’s not the only thing that people wonder about.

Introduction to CBD Oil

These are good questions because any medication or supplement a person takes could have potential side effects or adverse reactions. Most people know that use of CBD doesn’t get you “high,” but they still might not know that they can have other reactions from CBD. So what exactly is CBD? And how does it work in the body to promote health and wellness?

What is CBD?

The Agriculture Improvement Act of 2018, also known as the Farm Bill, defined Cannabis sativa plants with no more than 0.3% tetrahydrocannabinol (THC) as "hemp plants," and legalized their cultivation nationwide. These specific strains of cannabis are rich in the compound CBD, and companies utilizing this main cannabinoid component sprang up overnight.

CBD and THC are just a couple chemical compounds found exclusively in cannabis plants called cannabinoids. Some state laws allow medical marijuana to be sold, which is high in THC content and produces the psychoactive effects identified as feeling "high." The hemp plant is high in CBD content, which is preferred by many people because it doesn't have the same consciousness altering effects as medical marijuana.

When people are looking to experience the wide variety of health benefits that have been attributed to cannabis, but want to avoid getting high, CBD from hemp is what they should look for.  

How do you Take CBD?

CBD is available in a wide variety of formsCBD oil is most common: it is simply the cannabis extract blended with a neutral oil as a carrier. But CBD can also come in CBD capsulesCBD creamCBD gummies, beauty products, coffee, protein powders, vaping products, etc. With CBD, anything can be elevated to a wellness product.

How Does CBD Work?

Preliminary research shows that using CBD can have powerful effects on many functions of the human body resulting in a multitude of health benefits. It does this by interacting with a recently discovered system in the body called the endocannabinoid system (ECS).

The ECS is a network of cannabinoid receptors that are found overlaying the nervous system and throughout the entire body. These receptors bind to cannabinoids produced by the body and work to bring the body to homeostasis, like working to reduce pain or reduce anxiety. Supplementing with CBD from the cannabis plant stimulates the body to produce its own cannabinoids, thereby helping the ECS to operate at maximum capacity.

When all of the CBD compounds including trace amounts of THC work together in the body, it is called the "entourage effect." This effect allows the ECS to work better than it would if some compounds were missing. This is why full spectrum CBD oil is considered to be more effective than THC free products, like broad spectrum CBD or CBD isolates.

What Dosage of CBD is Safe?

WebMD, the popular medical information website, categorizes CBD as “possibly safe” if taken orally (like a capsule) or under the tongue (like a sublingual oil) in doses of up to 300 mg per day. Generally speaking, Cornbread Hemp customers rarely exceed a 100 mg dose of CBD per day. For instance, one Cornbread Hemp CBD capsule is 25 mg of CBD, so it would require 12 capsules per day to achieve a 300 mg daily dose of CBD. Our capsule customers tend to take between one to three capsules per day, far less than 300 mg of CBD.1

The right CBD dosage depends on a wide range of factors including body weight, metabolism, and individual needs. Someone looking for natural alternatives to potentially replace their medications would need much higher doses than someone who is just looking for help sleeping or with mild pain management. (Keep in mind that all health topics and decisions should be discussed with your physician before trying CBD!)

The World Health Organization has concluded that CBD from hemp cannabis extracts do not have any potential for harm, or abuse. CBD may actually rewire the brain circuits responsible for drug addiction, making CBD an important research candidate in the fight against a serious public health crisis: opioid substance abuse.

No one has ever overdosed from CBD, but people might still experience mild side effects from high doses. So this article will help answer the question: “What are the side effects associated with CBD?”

Physiological Side Effects of CBD

CBD is generally considered to be well-tolerated, but it can cause some mild physiological reactions. Physiological means effects felt by the body.2 

Diarrhea is a potential side effect of CBD oil. This reaction is sometimes caused by the carrier oil, not the CBD itself. Hempseed oil and MCT coconut oil are frequently used as carrier oils for CBD. And both have been found to cause diarrhea in some people.3

Drowsiness is sometimes associated with taking too much CBD. While studies show that CBD may help with sleep, they also show that taking too much CBD could cause feelings of grogginess and lethargy. That's why health care professionals do not recommend taking CBD oil before driving.

Neurological Side Effect

Most of the negative CBD effects reported are physiological in nature. CBD can inhibit THC from binding to cannabinoid receptors in the brain, and CBD doesn't have psychoactive properties, so any negative neurological reactions may be attributed to other sources.

Even though CBD may not affect the brain like THC does, preliminary research and trials suggest that CBD may still affect the brain other positive ways. CBD could have anxiolytic properties, meaning it may be used to help treat anxiety and depression.

The clinical trials conducted by Crippa et al. published in the September 2010 edition of the Journal of Psychopharmacology found that CBD changed the way the participants’ brains responded to anxiety, and they began to feel better. The researchers found that CBD increased the blood flow to the areas of the brain that are linked to anxiety disorders and stress.5

The anxiolytic properties of CBD can be more attributed to the effect CBD has on the body by helping with oxidative stress, rather than directly on the mind. But this balancing of the body can have auxiliary effects on the mind's state of well being. For example, stress is often accompanied by high blood pressure. Once blood pressure normalizes, then the stress felt by the body is reduced, which could help the person relax mentally. Researchers are still studying the benefits of CBD being used to treat anxiety related issues, but it seems that the results are more promising with every clinical trial.

CBD's Effects on the Immune System

CBD may help play a role in regulating the immune system since CBD receptors have been found on immune cells. Several studies have shown that CBD can help control the inflammatory response of the body which may be important for those with chronic pain.6 

The preliminary research tells us that CBD has potential immunosuppressant qualities. If future clinical trials confirm current research and anecdotal reports, then CBD will be shown to have anti-inflammatory effects. Inflammation is caused by the immune system to ward off infection and injury. By suppressing this response, CBD could have effects on the immune system.7 

A review of available research on CBD and the immune system was published in February 2020. While the authors confirm the data indicates that CBD likely possesses anti-inflammatory qualities, they also stress that more research is needed in human studies to fully understand the effects and benefits CBD has on the immune system.8

CBD and Drug Interactions

When a person swallows a CBD capsule, the stomach digests the gelatin capsule, and the CBD enters the system through the liver. The liver plays a key role in drug metabolism by digesting compounds that enter the body through the digestive system. That’s why this particular organ is so important when it comes to CBD and how it might interact with prescription medications.

Because CBD passes through the same liver pathway as many medications, CBD can affect how the liver metabolizes these medications. Specifically, CBD can neutralize a liver enzyme called cytochrome P450.9

This is important information to know for someone wanting to use CBD to address their health problems, especially for someone taking blood thinners.10 Any medication that comes with a “grapefruit warning” might also interact with CBD. That’s because CBD and grapefruit juice interfere with the P450 liver enzymes in the same way.11 It's worthy to note that those with liver disease should exercise extreme caution with CBD oil to avoid further liver injury.  

Allergic Reactions to CBD Oil

In rare instances, a person can be allergic to cannabis, and this can include hemp derived CBD oil and CBD topical products. If a person with a cannabis allergy ingests cannabis, they can experience symptoms that include:

  • Coughing
  • Congestion
  • Sneezing
  • Itchy eyes
  • Runny nose
  • Sore throat
  • Nausea

If a person with a cannabis allergy touches cannabis, or puts a cannabis derived topical preparation on their skin, they could experience symptoms similar to contact dermatitis, which include:

  • Dry skin
  • Hives
  • Itchy skin
  • Inflamed skin
  • Blisters

In very rare circumstances, a person with a cannabis allergy can experience anaphylaxis, or a severe allergic reaction.12 Seek medical attention immediately if you think you are experiencing an allergic reaction.

CBD Oil for Pregnant or Breastfeeding Women

CBD may not be safe for people who are pregnant or breast feeding, according to medical information website WebMD. CBD has been detected in the breast milk of users of cannabis products, and it is unknown how that can effect an infant. Until more research is completed, it is recommended to avoid CBD if you’re pregnant or breastfeeding.13

Side Effects from Bad CBD Oil

The FDA has not yet issued regulations on the labeling accuracy of cannabidiol extracts, nor the adequate testing of said products. This has allowed shady characters to run dishonest businesses and take advantage of unsuspecting consumers. Many of these bad CBD products are labeled incorrectly, or are contaminated with dangerous chemicals. Taking bad CBD products like these could cause a person to experience negative effects because of exposure to a range of unwanted substances, including: 

  • Pesticides
  • Heavy metals
  • Solvents
  • Mold
  • Fungus
  • Bacteria
  • Rancid carrier oil
  • Synthetic cannabinoids
  • Higher THC level than desired

Exposure to any of these can cause acute illness and long term health issues. Side effects of too much THC could cause dry mouth, altered mood and thoughts, changes in appetite, and the sensation of feeling “high.”

There have been many news reports of poorly labeled CBD oil products.14 There have also been reports of products containing synthetic cannabinoids sending people to the hospital, making bad CBD a serious health risk.15

Choosing the Best CBD

Looking at all the cannabidiol extracts sold online can be daunting, and we now know that they may contain harmful properties! So how do you know who to trust? And which is the best CBD product to get? Luckily, there are a few things you can look for when choosing a CBD oil to make sure you are getting a safe and potent product:

USDA Certified Organic: The only way to know for sure that a CBD product is free of any of the potential contaminants listed above is to look for high quality products carrying the USDA organic seal. USDA certified organic CBD oils are the only products guaranteed to be free from harmful contaminants. Cornbread Hemp is the first brand in the Midwest to attain the USDA certified organic seal on a CBD product; this is a telltale sign of quality. 

Third Party Lab Testing: A trustworthy CBD company will provide third party lab tests to prove that their products do not contain harmful materials. These tests must be from a third party to ensure that the results were not altered by the company. Third party lab reports, called Certificates of Analysis (COA), can also tell you the potency of the product. Marijuana CBD will have high amounts of THC, which you may not be looking for. Federally legal full spectrum hemp CBD will have less than 0.3% THC. Cornbread Hemp makes it easy by having scannable QR codes on every product label that takes you directly to the lab reports

Domestically Sourced: Cornbread Hemp uses the flowers from organic hemp grown in Kentucky for their base extract. Cannabis loves growing in the Bluegrass state, and by using only the flowers, Cornbread Hemp's CBD oil is more potent than companies who use leaves and stems for their extract material.

Quality Ingredients: To make their USDA certified organic CBD oils, Cornbread Hemp uses organic MCT coconut oil as a carrier. The MCT oil molecules are small, and are the perfect vehicle to carry CBD across skin membranes.

Full Spectrum: Cornbread Hemp's products are all full spectrum, meaning they have the full range of cannabinoids, including CBD and THC (in trace amounts). This allows for the entourage effect to increase the amount of health benefits you can enjoy. THC free products tend to not work as well, and there is no guarantee you can pass a drug test with them anyway.

Bottom Line: CBD Oil Side Effects

Reputable health organizations regard CBD from hemp to be safe with no risk of overdose or abuse. There have only been a few mild side effects reported with CBD use in human studies, including fatigue, dry mouth, and intestinal discomfort.

However, CBD intake does have the potential to affect how the body digests prescription drugs, which could lead to more serious reactions. Use of CBD might also directly affect the liver and immune system, so anyone with liver problems, a compromised immune system, or any other health conditions should consult their doctor before using CBD.

In the end, the simple answer is that more research is needed to gather the scientific evidence needed to fully understand the health benefits of CBD. It may lead to advances in how we help people relieve pain, anxiety, and depression. More evidence is also needed to fully determine if CBD side effects are a significant problem, or something mild and easy to navigate.16

About the Author
Dr. Leslie Mudd, PharmD

A board certified oncology pharmacist with 25 years experience at the James Graham Brown Cancer Center in Louisville, Kentucky. Dr. Leslie Mudd now serves as the Cornbread Hemp resident pharmacist and medical expert. Read Dr. Mudd's Full author bio here.


CBD may not be safe for people who are pregnant or breast feeding, according to medical information website WebMD. CBD has been detected in the breast milk of users of cannabis products, and it is unknown how that can effect an infant.

An anxiolytic is a medication or other intervention that reduces anxiety. CBD may be an anxiolytic for some people.

Diarrhea can result from taking CBD, but it may not be the CBD that's causing it. It may be the MCT carrier oil. Also drowsiness can occur. Be careful when driving or operating machinery.


1, 13 https://www.webmd.com/vitamins/ai/ingredientmono-1439/cannabidiol-cbd

 3, 4, 9. https://medium.com/alphagreen/everything-you-need-to-know-about-cbd-oil-side-effects-80a62fe6c876

5. Crippa JA, et al. “Neural basis of anxiolytic effects of cannabidiol (CBD) in generalized social anxiety disorder: a preliminary report.” Journal of Psychopharmacology. 2011 Jan;25(1):121-30. doi: 10.1177/0269881110379283. Epub 2010 Sep 9. PMID: 20829306.https://pubmed.ncbi.nlm.nih.gov/20829306/ 

6. Nagarkatti, Prakash et al. “Cannabinoids as novel anti-inflammatory drugs.” Future medicinal chemistry vol. 1,7 (2009): 1333-49. doi:10.4155/fmc.09.93   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828614/ 

7. https://canex.co.uk/how-does-cbd-affect-the-immune-system-and-autoimmune-disease/

8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173676/

10. https://www.healthline.com/nutrition/cbd-oil-benefits#TOC_TITLE_HDR_9 

12. https://www.medicalnewstoday.com/articles/321343#symptoms 

14. https://jamanetwork.com/journals/jama/fullarticle/2661569?mod=article_inline

16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569602/