Uses, Benefits, Side Effects, Dosage, Precautions
CBD Oil vs. Marijuana
 CBD Oil Marijuana
A component of the hemp plant Separate plant in the hemp family that contains CBD and hundreds of other compounds.
No or trace amounts of THC (0.3{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} or less) Significant amounts of THC
Works receptors in the brain, but not those that induce psychoactive effects (e.g., opioid receptors that help control pain, glycine receptors that impact mood control) THC binds to cannabinoid receptors in the brain to create a “high” feeling

What Are the Side Effects of CBD Oil?

Clinical research has shown that CBD oil can cause side effects. In one study, 91{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} of people with seizure disorders who took the prescription product Epidiolex had side effects from the medicine. The specific side effects and their severity vary from one person to the next and from one type of CBD to another.

Common Side Effects

The most common side effects of CBD oil that were reported include the following:

  • Change in appetite
  • Drowsiness or fatigue
  • Diarrhea
  • Change in liver enzymes

Severe Side Effects

Severe side effects have been noted in people with treatment-resistant epilepsy (ongoing seizures despite multiple medications). These include:

  • Status epilepticus (a life-threatening medical emergency where a seizure lasts longer than five minutes)
  • Pneumonia (infection of the air sacs in the lungs)

Also, consider that CBD products are not regulated and may be adulterated or labeled misleadingly. One study found that 21{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} of CBD products sold online also had THC. Severe side effects of THC, particularly at doses above 2.4 milligrams, can be quite severe and include:

  • Anxiety
  • Impaired cognition (lowered IQ scores and memory loss)
  • Psychosis (including suspiciousness, emotional withdrawal, and hallucinations)

If you notice these effects while using CBD oil, discontinue and discuss side effects with a healthcare provider as soon as possible.

Adolescent users are at increased risk of psychological disorders from THC. These psychological disorders include an increased risk of psychosis and schizophrenia.

Do not drive or use heavy machinery when taking CBD oil—especially when you first start using it or switch to a new brand. Remember that some products do contain THC, even in small amounts.


Your healthcare practitioner may advise against using CBD oil if you:

  • Have liver disease: CBD oil may increase liver enzymes, a marker of liver inflammation. Talk with your healthcare provider before taking CBD oil. You may need to check your liver enzymes regularly if you use CBD.
  • Have eye issues: CBD oil may also cause eye-related side effects. A 2018 study found that it may increase pressure inside the eyes. For people with glaucoma, this can make the condition worse. Some people also report dry eyes as a side effect of CBD oil.
  • Are pregnant or nursing: You should not use CBD oil if you’re pregnant or breastfeeding. Even though the effects of CBD are not fully understood, it does pass through the placenta. The American Academy of Pediatrics (AAP) further states that pregnant people should not use marijuana products because of the potential risks to developing fetuses.
  • Drink alcohol or take other sedating medications: Using CBD with these drugs could cause excess drowsiness.
  • Children: Children should not use CBD oil.

Dosage: How Much CBD Oil Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

There are no guidelines for CBD products or a “correct” dose of CBD oil. CBD has been used in doses ranging from 40 to 1,280 milligrams per day. For example, in one trial, patients admitted to the emergency room for acute back pain were given a one-time dose of 400 milligrams of CBD oil.

In another trial, schizophrenic patients were given 600 milligrams per day of CBD oil for six weeks. As a general rule, never take more than the recommended dose.

What Happens If I Take Too Much CBD?

Doses of up to 1,500 milligrams per day seem well-tolerated in adults. Keep an eye out for serious side effects like fatigue, changes in appetite, seizures, or pneumonia. And keep in mind that CBD may be adulterated and contain ingredients that are not listed, such as THC, and may not contain the amount of CBD listed on the bottle.

Children can be especially vulnerable. Dangerously slowed breathing has been noted in children who unintentionally ingested too much CBD oil.

CBD is also found in many foods and drinks in the US, so if you plan to consume these, discuss your total daily dose with your healthcare provider.

If you have questions or concerns about the use or unintended (accidental) ingestion of CBD products, please contact your healthcare provider, health department, or local or regional Poison Control Center at 800-222-1222. Call 911 if there’s an emergency.


CBD oil can interact with medications, including many used to treat epilepsy. One of the reasons for this has to do with how your body breaks down (metabolizes) drugs.

Cytochrome P450 (CYP450) is a liver enzyme your body uses to break down some drugs. CBD oil is broken down by and can also affect  CYP450. That means taking CBD oil with these drugs could have a more substantial effect than you need or make them not work as well.

Drugs that could potentially interact with CBD include:

  • Anticonvulsants like phenobarbital, Lamictal (lamotrigine), Onfi (clobazam), Dilantin (phenytoin), Tegretol (carbamazepine) and Trileptal (oxcarbazepine). In general, these will decrease the level of CBD. CBD increases lamotrigine levels.
  • Antidepressants like Paxil (paroxetine), Celexa (citalopram), Remeron (mirtazapine), and Tofranil (imipramine). CBD may increase the levels of these medicines and exacerbate their side effects.
  • Antifungals like ketoconazole
  • Antipsychotics like Haldol (haloperidol)
  • Benzodiazepine sedatives like Klonopin (clonazepam), Ativan (lorazepam), and Valium (diazepam). CBD decreases the effect of clonazepam and increases the impact of the others, which may increase side effects like drowsiness.
  • Echinacea species 
  • Erectile dysfunction drugs like Viagra (sildenafil)
  • Immune-suppressants like Sandimmune (cyclosporine). CBD may increase the levels of these drugs.
  • Macrolide antibiotics like clarithromycin 
  • Opioid painkillers like morphine. CBD increases the effect of morphine.
  • Rifampin-based drugs used to treat tuberculosis.
  • Statins to treat cholesterol like Lipitor (atorvastatin) and Zocor (simvastatin)

Always tell your healthcare provider and pharmacist about all your medicines, including prescription, OTC, herbal, or recreational drugs. Alcohol or other recreational drugs that cause drowsiness may have increased side effects if used with CBD oil.

The interactions between these medications and CBD may be mild, and you might not have to change your treatment. However, in some cases, you might have to change drugs or space out your doses to avoid a reaction. Never change or stop medication without talking to your provider.

It is essential to carefully read a product’s ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store CBD Oil

Store CBD oil in a dark, dry place. Refrigeration may help it to stay stable for a more extended period. For prescription Epidiolex, discard 12 weeks after opening the bottle. Discard after one year or as indicated on the packaging.

Keep this drug and all medications out of the reach of children and pets.

Similar Products

Other cannabinoids that are isolated from the cannabis plant are popping up in dispensaries and pharmacies, including the following:

  • CBC (cannabichromene)
  • CBDV (cannabidivarin)
  • CBG (cannabigerol), touted for digestive diseases
  • CBN (cannabinol) 

These products have very little evidence to support their use. More research is needed to clarify their safety and effectiveness. 

Supplements that are not cannabinoids but that act in similar ways include:

  • Palmitoylethanolamide (PEA): Targets similar pathways as CBD and may help with inflammation and pain
  • Echinacea: May help with anxiety
  • Kava: May help with anxiety and sleep by acting on the endocannabinoid system
  • Valerian
  • Passionflower
  • German chamomile
  • L-theanine
  • Magnesium
  • Melatonin

Frequently Asked Questions

  • Is one type of CBD oil better than another?

    CBD oil comes in different forms:

    • Isolates contain only CBD.
    • Broad-spectrum oils have nearly all of the components of the plant (e.g., proteins, flavonoids, terpenes, and chlorophyll) but do not have THC.
    • Full-spectrum oils have all the compounds, including THC (up to 0.3{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e})

    While some healthcare practitioners believe that the compounds provide more health benefits, there’s a lack of evidence to support these claims.

  • Are CBD oil and hemp oil the same?

    Not necessarily. While the names are sometimes used interchangeably, hemp oil can also refer to hemp seed oil, which is used for cooking, food production, and skincare products. CBD oil is made from the leaves, stems, buds, and flowers of the Cannabis indica or Cannabis sativa plant. It should contain less than 0.3{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} THC. Hemp oil is made from the seeds of Cannabis sativa and does not have TCH in it.

  • Is it possible to overdose on CBD oil?

    Yes. It’s possible to overdose on CBD oil, especially in children. Dangerously slowed breathing has been noted in children who unintentionally ingested CBD oil. It’s important to remember though that many CBD products have been found to also contain THC, which poses risks like heightened anxiety when taken at high doses.

  • Can I buy CBD oil in all US states? Is traveling with it between states okay?

    The legality of buying and selling CBD is quite murky. In 2018 it became legal to sell CBD oil that comes from the hemp plant and has less than 0.3{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} THC in it provided it is not marketed as a dietary supplement or claiming to treat medical conditions.

    Most states now allow the sale of CBD with low levels of THC, though it is still illegal in some states.

    For state-specific guidelines before traveling, check out a site like State Medical Cannabis Laws from the National Conference of State Legislatures. Some states do not allow CBD that has been purchased in other states.

  • How can I make sure the product I buy is of high quality?

    Choose products with a certificate of analysis (COA) from an independent lab and/or from companies with current Good Manufacturing Practices (cGMP) certification. The COA means that the product has been tested for CBD and THC levels, along with possible contaminants. Because CBD comes from a plant, it is susceptible to chemicals like pesticides.

    Make sure the lab making the product also meets ISO 17025 standards, which shows high scientific standards are met. The FDA has issued several warning levels to companies whose products are mislabeled or adulterated (they contain potentially unsafe ingredients that can make you sick). Check them out here and avoid buying these products if possible.

  • Can taking CBD cause a positive drug test?

    Studies have shown that pure CBD will not cause a positive urine drug screen, as these are designed to measure THC. However, CBD products such as full-spectrum oils that contain THC may result in positive drug tests.

  • Is CBD oil safe for pets?

    Not enough is known about CBD use in animals. Always discuss with a veterinarian before using a CBD product for your pet. The FDA suggests keeping an eye out for the following side effects: sleepiness, depression, heavy drooling, vomiting, agitation, tremors, and convulsions.

  • Can CBD oil get you high?

    As mentioned, CBD oil is from a plant (hemp, typically Cannabis ruderalis). Hemp is in the same family as the marijuana plant. However, CBD oil does not typically produce the feelings of euphoria that can make someone feel “high.”

    The reason why is that it does not contain enough tetrahydrocannabinol (THC). THC is the compound responsible for causing euphoria and other potential emotions, like paranoia.

Sources of CBD Oil & What to Look For

CBD can be derived from two types of cannabis plants—marijuana, which has a higher amount of THC, or hemp, which has a low amount of THC. Since 2018, the FDA has allowed CBD products to be sold as long as they have less than 0.3{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} THC.[cite] The FDA has made it illegal for companies to market CBD as dietary supplements or to claim that they treat specific conditions.

Remember that CBD oils are unregulated. There’s no guarantee that a product is what it claims to be on its packaging. You also can’t know for sure that it’s safe and effective. 

A 2017 study reported that only 31{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} of CBD products sold online were correctly labeled. Most had less CBD in them than was advertised, and 21{d589daddaa72454dba3eae1d85571f5c49413c31a8b21559e51d970df050cb0e} had significant amounts of THC.

Food Sources of CBD Oil

It is illegal to add CBD oil to food or drinks because an approved prescription product is available (Epidiolex for seizures). However, despite FDA warnings, CBD oil has increasingly been added to foods and beverages and can be found in different products such as coffee, chocolate, and sparkling water. 

CBD is thought to be absorbed better if taken with a meal higher in fat. CBD is lipophilic, meaning it dissolves best with fat.

CBD Oil Products

Available forms of CBD run the gamut and include:

  • Tinctures (CBD oil mixed with a base oil)
  • Capsules
  • Tablets
  • Gummies
  • Sprays
  • Creams
  • Gels
  • Inhalation liquids (vape pens)
  • Suppositories

Which product you choose primarily depends on your preference and what you hope to get in terms of effects. How fast your body absorbs the oil varies based on how it’s administered. For example, CBD starts to act within five minutes when it’s vaped vs. up to an hour when taken by mouth.

Note that vaping is harmful to both your body and anyone that you vape around due to secondhand exposure to toxins.

Each product works a bit differently, depending on the form, so following the directions and making healthier choices are essential.


The FDA does not regulate CBD oil, and contrary to popular opinion, it does come with some risks. Until more research is done on CBD oil, it’s important to remember that it may not live up to the hype and could even be dangerous. CBD products have not shown strong evidence of benefit for most of the advertised conditions.

There is significant variability among the products you’ll find at dispensaries, smoke shops, or online. Each product can contain very different amounts of CBD or THC than what’s listed on the package and can also contain harmful additives.

If you choose to use CBD oil, always discuss it with your healthcare provider to ensure it doesn’t interact with your prescription medications. CBD is not appropriate for pregnancy, breastfeeding, or in children.