CBD Side Effects, Drug Interactions and Allergic Reactions

CBD Side Effects

Dry Mouth  

Cottonmouth, also known as dry mouth, is a side effect of CBD that can cause you to feel dry in your mouth and eyes. According to a study, THC is more likely to cause this side effect, but CBD may also have this effect.

Possible Side Effects

CBD oil has been shown to cause side effects in clinical trials. People have varying types of side effects, especially when it comes to how bad they are and from which type of CBD they are taking.

CBD can cause side effects such as anxiety, mood changes, diarrhea, nausea, drowsiness,  and vomiting. It is also possible that CBD oil increases liver enzymes, a marker of inflammation in the liver. 

Before taking CBD oil, people with liver disease should speak to their healthcare provider. If they use CBD, regularly checking their liver enzyme levels may be necessary.

Effects on Pregnancy

According to the American Academy of Pediatrics (AAP), pregnant people are not recommended to use CBD since it may cause potential risks, especially to a growing baby.

Nausea, Fatigue, and Irritability

CBD can cause nausea, fatigue, and irritability as side effects. By competing with liver enzymes that break down blood thinning and other medicines, CBD can increase the blood levels of these drugs. Certain medications are also affected by grapefruit.  

Blood tests related to the liver may show abnormalities in people taking high doses of CBD. Many non-prescription medications, such as acetaminophen (Tylenol), are also true.

Other Effects of Other Drugs

Researchers examined some information regarding five prescription CBD and THC medications. Anti-nausea medication is used during cancer treatment, a medication used to treat muscle spasms in multiple sclerosis, and antiseizure medication. In total, researchers identified 139 medications as potentially being affected by CBD.

Researchers narrowed it down to 57 medicines for which altered concentrations may be dangerous. Among the drugs on the list are heart medications and antibiotics, though not all may be affected by CBD-only products. CBD may interact with certain medications, including warfarin, amiodarone, levothyroxine, clobazam, lamotrigine, and valproate.

Side Effects for Children With Epilepsy and Those Who Take Clobazam

Children with childhood epilepsy have also reported drowsiness, pneumonia, abnormal liver function test results, and drowsiness. These effects may result from interactions between CBD and other medications, including clobazam.

Negative Effects and Toxicity of CBD

CBD does not come without risk. Studies show that CBD may cause several adverse effects in animals. Also included are hepatocellular injuries, changes in organ weight, changes in men’s reproduction, and hypotension. 

Nevertheless, these complications only occur at doses that are above the ideal amount for human pharmacotherapy. There have been several reports of drug interactions, abnormalities, digestive problems, body pain, vomiting, and drowsiness in human CBD studies.

Other Side Effects

It was found during the review and approval process for Epidiolex that CBD has potential side effects, including liver damage, drug interactions, sedation, drowsiness, change in alertness, appetite loss, and diarrhea.

Long Term Consumption

CBD may have shown to be fairly safe to consume in limited studies. However, it is necessary to conduct further research to determine the effects of CBD on the entire body and its long-term effects.


CBD supplements may cause nausea in some people. CBD’s potency depends on the individual’s sensitivity to it, as well as the amount ingested. The amount of CBD absorbed by the body varies greatly due to the vast range of CBD supplements available, including oils, gummies, tinctures, and vapors. Combining this information with your unique circumstances will ultimately determine whether you experience CBD side effects.

Drowsiness, Digestive Discomfort, and Changes in Appetite or Weight

Some people report that CBD may cause drowsiness, digestive discomfort, and weight changes or changes in appetite when used.

The side effects of using a CBD cream, for example, may be much less severe than those associated with using an edible product. 

Effects of CBD as Dietary Supplements

There is a significant safety concern with CBD due to its marketing as a supplement rather than medication. The FDA currently does not regulate the purity and safety of dietary supplements. Therefore, you cannot be sure that the product you buy contains active ingredients in the dosage stated on the label. There may also be other unknown ingredients in the product. Additionally, consumers don’t know which CBD dose is most effective for any medical condition.

Liver Inflammation

CBD oil may also increase liver enzyme levels, which is a marker of inflammation of the liver. Those with liver disease should discuss CBD oil with their healthcare provider. When taking CBD, their liver enzymes may need to be checked regularly.


When consumed in appropriate doses, CBD may be safe. Patients have been given doses of up to 200 mg daily without experiencing adverse effects. Patients have used a prescription CBD product at higher doses and for longer periods with the guidance of a healthcare provider.

Dry Mouth, Low Blood Pressure, Light Headedness, and Drowsiness

In addition, CBD may have some side effects, such as drowsiness, low blood pressure, and dry mouth. A prescription form of CBD, Epidiolex, may have also been reported to cause liver damage with high doses.

CBD Drug Interactions

Drug Interactions

There are several potential drug interactions associated with CBD. Among these are warfarin, amiodarone, levothyroxine, clobazam, valproate, and lamotrigine.

CYP3A4  and CYP2D6 Inhibitors Risk

CBD may alter the serum assemblages of several medicines since the CYP3A4 enzyme metabolizes about one-quarter of all drugs.

CYP2D6 is responsible for the metabolism of many antidepressants, so CBD could increase SSRI, a tricyclic antidepressant, antipsychotic, beta-blocker, and opioid serum concentrations.

CNS Depressants

The depressant effects of CBD are additive to those of alcohol, barbiturates, and benzodiazepines. A small study found that CBD and opioids did not have additive effects on the CNS.


In terms of warfarin levels, THC and CBD may increase warfarin levels, according to a study conducted in 2012. High cannabis consumption has been linked to increased INR levels.


According to a study done in 2015, alcohol may have the potential to increase levels of THC.


According to a study conducted in 2014, smoked cannabis may decrease theophylline levels.

Indinavir or Nelfinavir  

According to a study made in 2003, smoked CBD does not affect people who take indinavir or nelfinavir.

Docetaxel or Irinotecan

According to research conducted in 2007, infusion of CBD as tea did not affect persons who take docetaxel or irinotecan.


According to some researchers in 2015, CBD may increase levels of clobazam in children who take such medications as a treatment for childhood epilepsy.

Other Medicines That Need Close Monitoring

There are several medicines on the list that needs close monitoring when taken with CBD. Among these are antidepressants like amitriptyline, clomipramine, and lofepramine. This list includes opioid pain medications such as fentanyl and oral contraceptives such as ethinylestradiol. The list also includes thyroid hormones, such as levothyroxine, sedatives like propofol, and blood thinners like acenocoumarol and warfarin. For your convenience, here is a list of all medicines.

Researchers published a long list of 139 medicines that also have the potential to interact with cannabinoids, but have a lower risk. As new drugs get approved and new evidence emerges, these lists will be routinely updated, say the authors.

CBD Allergic Reactions


Some individuals may experience itching due to CBD, according to a report issued by the MedicNeedand Healthcare Products Regulatory Agency (MHRA). According to the report, at least two cases of itching have occurred after taking CBD oil. Oral CBD consumption was associated with urticaria in one person. Several others used CBD both orally and topically and experienced itching as well.


One review, published in the journal Cannabis and Cannabinoid Research in 2017, determined that CBD is an effective, safe, and well-tolerated pharmaceutical alternative to many common pharmaceuticals.


There’s also a chance that taking or using CBD may make you allergic to some terpenes, such as D-limonene and linalool.

Epidiolex-induced skin rash

There has been one recorded case of Epidiolex-induced skin rashes. CBD therapy Epidiolex is FDA-approved only for treating a rare form of epilepsy caused by CBD.

Allergic Skin Reaction to Linalool and Limonene

According to some researchers, more than 20 percent of the 100 people they tested had a skin reaction to linalool, while 8 percent had a reaction to limonene. The majority of people with these kinds of contact allergies don’t work in cannabis production, but those who do could face serious health problems.

Hemp Seed Allergies

High-protein foods are the cause of many food allergies. CBD products, such as oral oils, are commonly made with hemp seed oil. CBD used in this way is often processed so that it is 100% fat, which reduces the possibility of a reaction. It is still possible to experience symptoms such as hives. If a consumer suffers from severe food allergies, he or she should always consult a doctor before taking CBD.

Ways of Accumulating Allergies From CBD

During exposure to CBD, people can develop an allergy or allergic sensitization, according to the American Academy of Allergy, Asthma, and Immunology (AAAAI). Allergens related to CBD can be ingested, inhaled, smoked, ingested or even touched.


A study published in 2013 suggests that some strains of cannabis such as Cannabis sativa may be particularly irritating.

Allergic Reactions Caused by Other Allergies

According to a 2018 small-scale study, people with allergies to cat dander, molds, dust mites, or plants may develop cannabis allergies.


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CBD Allergic Reactions