The benefits and side effects of using CBD oil

The benefits and side effects of using CBD oil
The FDA approved a CBD-derived drug to help treat rare forms of child epilepsy. CasarsaGuru/Getty Images
  • CBD oil is extracted from hemp and cannabis plants and infused in products like lotion and edibles.
  • Human clinical trials suggest that CBD oil can help relieve anxiety, inflammation, and epilepsy.
  • CBD can cause side effects including dry mouth, nausea, fatigue, irritability, and more.

Cannabidiol (CBD) oil is a concentrated extract from hemp and cannabis plants, which is then mixed with other ingredients to create an array of CBD products including capsules, tinctures, edibles, creams, and vapes.

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The purported health benefits of CBD are many, ranging from treating cancer to premenstrual syndrome. But like all popular remedies, the wide majority of marketing claims have yet to be proven.

Does CBD oil work?

There is some evidence in human clinical trials that large doses of CBD may be helpful for treating anxiety, epilepsy, addiction, inflammation, and psychosis, says Jeffrey Chen, MD, co-founder and CEO of Radicle Science, a health-tech company that offers research and validation services for CBD products.

In fact, in 2018, the FDA approved the use of Epidiolex, a CBD-derived drug, to treat rare forms of childhood epilepsy.

Additionally, there have been anecdotal reports of CBD helping with issues like pain, sleep disturbance, and stress. However, more significant human trials are needed to determine how well CBD treats these issues for a broad population, says Chen.


How to use CBD

There are many different ways you can use CBD. Deciding which method is best for you largely comes down to how quickly you want the effects to kick in.

The amount of time CBD takes to reach your bloodstream depends on the mode of consumption, says Chen:

  • Inhaling it is the fastest, since it goes from your lungs to your bloodstream, causing the CBD level in your bloodstream to peak in 30 minutes or less.
  • Putting it under your tongue allows it to get absorbed directly into your bloodstream. This is the second-fastest method, after inhalation.
  • Swallowing it requires the CBD to first pass through your intestines and then your liver before reaching your bloodstream, which can take hours.
  • Applying it to your skin often means it only works topically in that area and doesn't reach your bloodstream. However, using transdermal CBD patches may cause the CBD to penetrate the layers of your skin and reach your bloodstream.

"How long effects last is difficult to predict because people take different doses and experience different effects from CBD - and some do not experience an immediate effect at all," says Chen.

In terms of dosage, there isn't an established, recommended CBD dosage, says Chen.

While most consumer products recommend serving sizes of 5 to 50 milligrams, research studies that have demonstrated benefits typically use several hundred milligrams of pure, pharmaceutical-grade CBD per day.


These quantities are "not available, sustainable, or affordable," says Jordan Tishler, MD, ​​president of the Association of Cannabinoid Specialists and founder of InhaleMD.

Side effects of CBD

CBD is generally considered to be safe and well-tolerated. However, it can sometimes cause side effects, since it interacts with your central nervous system as well as several other organs in your body.

Side effects of CBD can include:

  • Dry mouth
  • Reduced appetite
  • Diarrhea
  • Nausea
  • Fatigue
  • Drowsiness
  • Irritability

If you're considering taking CBD oil or other CBD products, it's recommended that you consult your healthcare provider first, particularly if you:

  • Have underlying medical conditions such as kidney disease, liver disease, heart issues, a weakened immune system, or epilepsy.
  • Are taking other medications, since CBD can interact with 139 other drugs. Older adults or people who take multiple medications are at a greater risk of experiencing side effects from combining CBD with medication.

Is CBD oil safe?

CBD is generally considered safe, particularly in low doses. "While low-dose CBD is not particularly effective, it's not harmful either," says Tishler.


However, when you get to higher doses, CBD can cause liver toxicity and has been shown to interact dangerously with many medications like blood thinners and heart medications, Tishler says.

A major concern with CBD is that most products are sold as supplements, not medication, so they are not regulated by the FDA and therefore, may not have accurate dosing information.

A 2017 study investigated 84 consumer CBD products and found that two-thirds did not correctly state how much CBD they contained:

  • 26% of the products contained less CBD than they claimed
  • 42% contained more CBD than they claimed
  • 32% had correct dosing information

Important: The legalities of CBD oil are tricky and can depend on whether the CBD was extracted from hemp or cannabis. "Hemp is a type of cannabis that is low in THC and is legal at the federal level. High-THC cannabis is legal in dozens of states but illegal at the federal level," says Chen.

Insider's takeaway

While there are several CBD oils and products that claim to offer myriad health benefits, the science has not caught up with the marketing yet. So far, CBD has been approved by the FDA only for the treatment of epilepsy in children.


There isn't much data in adult humans to show that CBD is a useful medication, says Tishler. He says most of the studies investigating the effects of CBD have been conducted in mice and cell cultures, and the results don't necessarily apply to humans.

Since many of the effects of CBD are unknown, Chen recommends weighing the benefits you notice with any side effects you experience, before you decide to take it regularly.

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