What is CBD? The Complete Guide

Last Updated: August 2020

Cannabidiol (CBD) oil is an extremely popular supplement that people use for a variety of conditions, most notably to help with pain and anxiety. Although a derivative of marijuana, it doesn’t get you high. This gives CBD oil a more broad appeal.

If you’re interested in trying CBD oil, it can be difficult to know where to start. Here’s our complete guide to CBD, including what it is, how it works, benefits and downsides, and how to choose a product and dose.

What is CBD?

CBD is a compound extracted from cannabis, or the hemp plant. It’s considered a phytocannabinoid. There are two primary phytocannabinoids found in cannabis: tetrahydrocannabinol (THC) and CBD. While THC can get you high, CBD can’t.

By law, CBD products can’t contain more than 0.3% of THC by volume.

This makes CBD more appropriate for a number of people—not only adults who don’t want to get high, but also children who may benefit from phytocannabinoid use. People even give CBD to their dogs to help with anxiety, seizures, and pain management.

How it works

CBD works by acting on your body’s endocannabinoid system. Endocannabinoids are cannabinoids that your body produces on its own, and the endocannabinoid system is a network of receptors on the cells across your body that endocannabinoids or phytocannabinoids can engage with.

While most endocannabinoid receptors are found on the cells of your brain and central nervous system, there are actually endocannabinoid receptors all over your body.

The endocannabinoid system is tasked with helping to maintain homeostasis, or balance, in your body. This means that it can affect your body in a number of different ways, from the pain response to stress to digestion, metabolism, and more.


CBD has numerous potential benefits, many of them related to its anti-inflammatory and blood pressure-reducing capacity. It’s mostly used for pain and anxiety, but may have some other benefits as well.

Although more research is needed, CBD presents a seemingly safe, natural, and non-addictive alternative to prescription pain and anxiety meds.


CBD has some anti-inflammatory and blood pressure lowering properties. Because these two factors (inflammation and high blood pressure) can worsen pain, CBD oil may be able to reduce pain by improving them. Additionally, it can directly affect the endocannabinoid system to help block pain in some instances—although, more research is needed to fully understand this process.

One survey of 93 current or former CBD users with autoimmune hepatitis showed that about 70% of them used CBD for pain management, 80% of them reported that CBD actually helped them manage their pain, and a handful of them were even able to discontinue use of prescription pain medications after starting CBD.

Although strong evidence for CBD use for pain management is lacking, there is some convincing evidence to support the use of cannabis and cannabinoids in general. 


CBD can directly act on endocannabinoid receptors that are partially responsible for the fear response, dampening the fear response and—therefore—stress levels. Outside of the endocannabinoid system, it may also be able to act directly on certain serotonin receptors, which can also help to reduce anxiety.

One study of 72 adults (47 with anxiety, and 25 with self-reported poor sleep) being followed at a psychiatric clinic found that—after starting CBD—72% of the adults experienced significant improvements in their anxiety levels. Additionally, 66% experienced better sleep, and these improvements were after just one month of CBD use.

CBD may also be beneficial for a number of other mental, personality, or social disorders. For instance, some studies show that it may help with the treatment of seizure disorders, post-traumatic stress disorder, bipolar disorder, depression, and Parkinson’s disease.

Other benefits

Many people have found other uses for CBD as well. Although research on these benefits is extremely limited, they’ve been reported anecdotally. These potential benefits include weight loss, acne control, and nausea.

However, it’s important to remember—even for the more common uses of CBD oil like pain and anxiety—there is a definite lack of high-quality, double-blinded, randomized-controlled trials. Although we can see associations from weaker studies, these high-quality trials are needed to establish that there’s a causal relationship between CBD and these benefits.


Unfortunately, due to something known as the “entourage effect,” CBD alone may not be as effective or helpful for these conditions as cannabis in its entirety. In whole cannabis, CBD, THC, and terpenes—or volatile compounds that provide cannabis its strong scent (as well as some health benefits)—work together synergistically to have a greater effect than each compound in isolation.

Regardless, CBD is still the best alternative for people who don’t want to get high. 

What’s more, while CBD is mostly safe, and has even been found to cause few complications in doses as high as 1,500 mg per day, it may cause some side effects in certain people. Some of these potential side effects include:

  • Changes to your appetite: While cannabis causes “the munchies,” CBD often has the opposite effect. Many people have reported an appetite suppressing effect from using CBD. However, some animal studies have noted increased appetite after CBD use. These appetite changes can also result in changes to your weight. While for some people this may be a good thing, for others it may be an unwanted side effect.
  • Fatigue or sedation: CBD lowers your blood pressure, which is one of the ways in which it can help with managing pain and anxiety. Unfortunately, this can also result in excessive fatigue or even a sedative effect in some people.
  • Dry mouth: Cannabinoids may reduce your body’s saliva production, leading to dry mouth. To help combat this, drink plenty of fluids.
  • Diarrhea: Another possible side effect caused by CBD’s relaxant properties, diarrhea may happen—especially when you first start using CBD—as a result of the muscles of the digestive system relaxing. This allows the products of digestion to travel through your digestive tract more quickly than they normally would.
  • Worsening anxiety: In one mouse study, researchers have noted that—while many subjects had a decreased fear response after cannabinoid use, some subjects had an increased fear response. Note that this study wasn’t specifically about CBD, but about other cannabinoids.
  • Low blood pressure: As mentioned above, CBD can lower your blood pressure. While for some people this is harmless or even beneficial, those with naturally low blood pressure and those taking blood pressure medications will need to be cautious. If you have low blood pressure or are on a blood pressure medication, be sure to consult your doctor before you start using CBD.

If you’re experiencing symptoms after using CBD, you should either decrease your dose or discontinue taking it altogether.

In many human studies, changes in liver markers are also noted as a side effect of CBD use. Liver failure has been induced in rats receiving extremely high doses of CBD, as well. However, it would be nearly impossible for a person to consume the amount of CBD needed to damage their liver to this extent.

Additionally, CBD may react with certain medications, including heart, seizure, and anxiety meds. This is because CBD and many drugs are both metabolized using the cytochrome P450 (CYP450) enzyme. 

A general rule of thumb is that if grapefruit juice is contraindicated with a certain medication, you should be cautious when taking CBD while on that medication as well. 

Grapefruit juice contains compounds called furanocoumarins that can affect your body’s ability to metabolize a drug and remove it from your system by monopolizing CYP450. This can often result in a drug staying in your system longer than it should, essentially providing a higher dose than what was prescribed to you. CBD may have a similar effect in regards to CYP450.

There are over 85 prescription medications that can be affected by grapefruit juice, and therefore CBD potentially. If you’re taking any prescription medications, it’s best to talk to your doctor before you start using CBD.

Choosing a CBD product

Ready to make a purchase? Don’t just buy the first CBD oil you see. To ensure that the product you choose is as safe and effective as possible, here are some things you should look for:

  • USA-grown, organic CBD: To ensure that your CBD top-notch, stick to CBD that’s sourced from USA-grown, organic hemp. This provides some assurance that the hemp meets the agricultural standards required to be grown in the US and is free of pesticides.
  • Third-party testing: CBD oils are considered dietary supplements, and therefore they are only minimally regulated by the Food and Drug Administration. Unfortunately, these minimal regulations leave room for some manufacturers to produce a CBD product that’s impure or that doesn’t contain what the label says it contains. For instance, many CBD products contain higher-than-legal amounts of THC. Third-party testing offers some protection from this by allowing you to read the results of an independently run test and compare them to what the product label states. Look for CBD products that make the third-party reports easily accessible on their website.
  • Minimal additives: CBD oils should contain only a handful of ingredients: CBD, a carrier oil, and possibly a flavor—although unflavored CBD oils are your best bet. They’re more versatile and free of natural or artificial flavorings. An ingredient list much longer than this could be a tip-off that the product is lower in quality. CBD edibles, of course, will have more ingredients and additives such as sweeteners, stabilizers, or preservatives.

CBD oil may be a better choice than CBD edibles, especially if you’re new to CBD. The oil allows you complete flexibility over dosing.

For pain, you can also try topical CBD in a lotion or cream. Be sure to purchase one that meets the standards listed above, but is also formulated specifically for topical use. You shouldn’t apply edible CBD products oil to your skin, and you definitely shouldn’t ingest topical CBD products.

Dosing guidelines

When it comes to CBD, you should start with the absolute lowest dose you can. For oils, this is usually anywhere from 20-25 mg of CBD.

Since CBD can have a relaxing effect, you may want to start off by taking it in the evenings. The oil can be dropped directly into your mouth, under the tongue, for the quickest absorption.

For a week or two, assess how the oil is working for you. If needed, you can then increase your dose by around 10 mg per day. Keep increasing your dose in small increments every week or two until you’re experiencing the desired amount of effect from CBD.

Over time, you may find that taking two or more daily doses works better for you.

Remember, if at any point you start to experience unwanted side effects you should either decrease your dose or discontinue using the CBD immediately. Severe side effects may warrant a trip to your doctor, or even to the emergency room (for instance, if you think you’re having an allergic reaction to a CBD product).

However, for most people, doses of up to 1,500 mg of CBD per day appear to be safe—although it’s unlikely that you’ll need a dose that’s even nearly this high to experience the results you’re looking for.


CBD oil is a supplement derived from hemp that may provide some powerful benefits, without getting you high like cannabis. It works by acting on your body’s endocannabinoid system.

It’s commonly used for pain and anxiety, but may have several other uses as well. Unfortunately, there’s not a great deal of high-quality scientific evidence regarding CBD use yet.

Although mostly safe, CBD can have some side effects and may interact with some medications.

You should choose CBD products that are USA-grown, organic, third-party tested, and free of unnecessary additives. As a beginner, you should start with the lowest dose possible and slowly increase as needed.

Overall, CBD oil appears to be a safe option to help with pain and anxiety, but more high-quality research is needed.

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