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Cannabidiol Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Jan 9, 2023.

Applies to cannabidiol: oral solution.

Serious side effects of Cannabidiol

Along with its needed effects, cannabidiol may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking cannabidiol:

More common

Less common

Other side effects of Cannabidiol

Some side effects of cannabidiol may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to cannabidiol: oral liquid.


The more commonly reported adverse reactions have included somnolence, decreased appetite, diarrhea, transaminase elevations, rash, and insomnia.[Ref]


Very common (10% or more): Elevated hepatic transaminases (up to 25%)

In clinical trials, 13% (10 and 20 mg/kg/day) and 12% (25 mg/kg/day) of drug-treated patients experienced hepatic transaminase elevations of greater than 3 times the upper limit of normal (3 x ULN) compared to 1% in placebo patients. Less than 1% had elevations greater than 20 x ULN. In clinical trials with doses of 10 and 20 mg/kg/day, ALT elevations greater than 3 x ULN occurred in 30% of patients taking both concomitant valproate and clobazam; 21% taking concomitant valproate; 4% concomitant clobazam and 3% taking neither valproate or clobazam. With doses of 25 mg/kg/day, ALT elevations of 3 x ULN occurred in 20% of patients taking both concomitant valproate and clobazam; 25% taking concomitant valproate; 0% concomitant clobazam and 6% taking neither valproate or clobazam.

Transaminase elevations were generally dose related. ALT elevations greater than 3 x ULN occurred in 17% of patients taking 10 or 20 mg/kg/day and 12% taking 20 or 25 mg/kg/day, compared to 1% in patients taking 10 mg/kg/day.

Patients with baseline transaminase elevations above the ULN had higher rates of treatment emergent ALT elevations. For patients taking 20 mg/kg/day, ALT elevations to greater than 3 x ULN occurred in 30% of patients who had baseline ALT elevations compared to 12% in patients whose ALT levels were within the normal range at baseline.


Common (1% to 10%): Insomnia, sleep disorder, poor quality sleep, irritability, agitation, aggression, anger[Ref]

Nervous system

Somnolence and sedation (including lethargy) occurred in 32% of patients compared with 11% of those on placebo. Occurrences were higher among patients on higher doses (34% vs 27% for doses of 20 mg/kg/day and 10 mg/kg/day, respectively). Occurrences were even higher in patients on concomitant clobazam (46% vs 16%).[Ref]

Very common (10% or more): Somnolence (up to 25%)

Common (1% to 10%): Sedation, lethargy, gait disturbance[Ref]


Frequency not reported: Hypersensitivity reaction (pruritus, erythema, angioedema)[Ref]


Very common (10% or more): Decreased appetite (up to 22%)

Common (1% to 10%): Decreased weight[Ref]


Very common (10% or more): Laboratory-defined anemia (up to 38%)

Common (1% to 10%): Anemia, decreased platelet count, increased eosinophil count[Ref]

In clinical trials among patients with Lennox-Gastaut syndrome (LGS) or Dravet syndrome (DS), mean decreases in hemoglobin (0.42 g/dL) and hematocrit of (1.5%) occurred in patients receiving this drug (compared with -0.03 g/dL and -0.4%, respectively in placebo). Among patients treated for tuberous sclerosis complex (TSC), a mean decrease in hemoglobin of 0.37 g/dL (compared to 0.07 g/dL in placebo) and drop in hematocrit of 1.2% (compared to 0.2% for placebo). A new laboratory-defined anemia defined as a normal hemoglobin at baseline and a reported value less than the lower limit of normal at a subsequent time occurred in 30% of patients in the LGS and DS trials (placebo=13%) and 38% of patients in the TSC trials (placebo=15%).[Ref]


Very common (10% or more): Viral infection (up to 11%), other infection (up to 21%)

Common (1% to 10%): Fungal infection[Ref]


Common (1% to 10%): Pneumonia, hypoxia, respiratory failure, rhinorrhea[Ref]


Very common (10% or more): Pyrexia (up to 19%), fatigue, malaise, and asthenia (up to 12%)

Common (1% to 10%): Ear infection[Ref]


Frequency not reported: Increases in creatinine[Ref]

Increased serum creatinine has been observed with use of this drug in healthy adults, in patients with Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. The mechanism has not been determined. An increase of about 10% has been observed within 2 weeks of initiating therapy. In healthy adults, this increase was reversible. Reversibility was not assessed in patients with Lennox-Gastaut syndrome, Dravet syndrome, or tuberous sclerosis complex.[Ref]


Very common (10% or more): Rash (up to 13%)[Ref]


Very common (10% or more): Diarrhea (up to 31%), vomiting (up to 17%)

Common (1% to 10%): Drooling, salivary hypersecretion, gastroenteritis, abdominal pain, nausea[Ref]


Common (1% to 10%): Urinary tract infection

Frequently asked questions


1. Product Information. Epidiolex (cannabidiol). Greenwich Biosciences LLC. 2018.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.