By Marcus Reid | Last updated: June 15, 2026
CBD is generally considered safe, and most people who use it regularly report tolerating it well. But “generally safe” is not the same as “no side effects,” and anyone considering CBD should understand what the research actually says about risks before starting.
This article covers the side effects documented in clinical research, the drug interaction risk that matters most from a safety standpoint, what the World Health Organization has concluded about CBD’s safety profile, and who should be cautious about using it.
What the WHO Says About CBD Safety
In 2018, the World Health Organization’s Expert Committee on Drug Dependence published a critical review of cannabidiol. Its conclusions on safety were broadly reassuring: CBD has a good safety profile, does not appear to cause physical dependence, and has not been associated with abuse potential in humans or animals.
The committee also noted that CBD is generally well-tolerated, with a good safety profile observed in both clinical trials and post-market monitoring of Epidiolex, the FDA-approved CBD medication. That said, the committee acknowledged that most studies to date have been relatively short in duration, and long-term safety data remains limited.
Common Side Effects of CBD
The side effects reported most consistently in clinical trials and user surveys include:
Dry mouth: CBD reduces saliva production by interacting with receptors in the salivary glands. This is one of the most commonly reported side effects, though it is mild and temporary. Staying hydrated helps manage it.
Drowsiness and fatigue: At higher doses, CBD can cause drowsiness. This is more commonly reported at doses above 150mg and may actually be desired by people using CBD for sleep. At lower doses used by most people (10 to 50mg per day), sedation is less common.
Changes in appetite: Some users report reduced appetite with CBD use. Interestingly, this contrasts with THC, which typically increases appetite. In clinical trials of Epidiolex in children, decreased appetite was one of the more consistently reported adverse events.
Diarrhea and gastrointestinal discomfort: Particularly associated with high-dose CBD oil rather than gummies or capsules. The carrier oil used in tinctures (often MCT or hemp seed oil) can contribute to digestive upset in some people, especially when starting out or taking large amounts.
Liver enzyme elevation: At high doses, CBD has been associated with elevated liver enzymes in some clinical studies. This was notably observed in trials of Epidiolex at doses significantly higher than typical consumer use. At doses used in most commercial products (under 100mg per day), this risk appears minimal, but people with existing liver conditions should be aware of it.
CBD Drug Interactions: The Risk That Matters Most
The most clinically significant safety concern with CBD is not its direct side effects but its interaction with prescription medications. This is not a minor issue and deserves clear explanation.
CBD inhibits a family of liver enzymes called cytochrome P450 (CYP450), specifically CYP3A4 and CYP2D6. These enzymes are responsible for metabolizing a large proportion of prescription medications, estimated at 60% of all clinical drugs. When CBD inhibits these enzymes, it slows the metabolism of those drugs, which can cause them to accumulate in the bloodstream at higher levels than intended.
Medications with a narrow therapeutic window (where the difference between an effective dose and a toxic dose is small) are most affected. Examples include:
- Warfarin (blood thinner): CBD can significantly increase warfarin levels, raising the risk of bleeding. Case reports have documented this interaction in real patients.
- Antiepileptic drugs: Ironically, CBD itself is used for epilepsy, but it can also increase levels of other antiepileptics like clobazam and valproate, requiring dose adjustments.
- Certain antidepressants and antipsychotics: Including some SSRIs and tricyclics that are metabolized by CYP2D6.
- Statins and calcium channel blockers: Some cardiovascular medications metabolized by CYP3A4.
- Immunosuppressants: Including cyclosporine, used in transplant patients.
If you take any prescription medication, particularly one that comes with a “grapefruit warning” (grapefruit inhibits the same enzyme system), speak with your prescribing doctor before using CBD. This is not a reason to avoid CBD automatically, but it is a conversation worth having.
Who Should Be Most Cautious About CBD?
People taking prescription medications: As described above. The interaction risk is the most important safety consideration for this group.
Pregnant or breastfeeding women: The FDA advises against using CBD during pregnancy or while breastfeeding. Animal studies have shown that CBD can affect fetal development, and CBD has been detected in breast milk. Until more human data is available, the precautionary recommendation is to avoid it during these periods.
People with liver disease: Given the potential for liver enzyme elevation at high doses, individuals with pre-existing liver conditions should use CBD with caution and under medical supervision.
Children: Outside of clinically prescribed Epidiolex for specific epilepsy conditions, CBD is not approved for use in children. Pediatric use should only occur under medical supervision.
Does CBD Cause Long-Term Side Effects?
Long-term safety data on CBD is still limited. Most clinical trials have run for weeks to a few months, not years. The longest-term data we have comes from post-market monitoring of Epidiolex, which has been in use since 2018. Based on that data and existing research, there is no strong evidence that CBD causes long-term harm at typical consumer doses.
That said, the absence of evidence of long-term harm is not the same as evidence of long-term safety. If you use CBD regularly, periodic check-ins with a healthcare provider are reasonable, particularly if you also take prescription medications.
Frequently Asked Questions
Can you overdose on CBD?
There are no recorded fatalities from CBD overdose, and animal studies suggest a very high toxic threshold. Clinical trials have used doses up to 1,500mg per day without serious adverse events in healthy adults. That said, very high doses do increase the risk of side effects like drowsiness, diarrhea, and liver enzyme elevation. Stick to manufacturer-recommended doses and consult a doctor if you want to use unusually high amounts.
Does CBD affect mental health?
At normal doses, CBD has not been shown to cause negative mental health effects and may have positive effects on anxiety in some users. Unlike THC, CBD does not appear to trigger or worsen psychosis. Some research has even suggested CBD may partially counteract THC-induced anxiety in people who consume cannabis. However, at very high doses, some users report mild mood changes or increased anxiety, which is inconsistent with most research findings and may be dose-dependent.
Is CBD safe for older adults?
CBD may be appropriate for older adults for pain, sleep, or anxiety, but the drug interaction risk is particularly important in this population because older adults are more likely to take multiple prescription medications. Anyone over 65 who takes prescription drugs should speak with their doctor before starting CBD. The drowsiness side effect is also worth monitoring, as it can increase fall risk in older individuals.
Does CBD show up on a drug test?
CBD itself is not what drug tests look for. Tests screen for THC metabolites. Pure CBD isolate will not trigger a positive result. Full-spectrum products containing trace THC can, with regular high-dose use, lead to accumulation of THC metabolites that may reach detectable levels. If drug testing is a concern, use broad-spectrum or isolate products with a COA confirming non-detectable THC.
Related reading: The Complete CBD Guide | How Does CBD Work? | How to Choose a Quality CBD Product
