CBD oil is generally safe for most adults at low to moderate doses. The World Health Organization describes CBD as “well tolerated with a good safety profile,” and there is no evidence it carries any risk of abuse or dependence. That said, CBD is not risk-free. It can cause side effects, stress the liver at high doses, interact with certain medications, and the unregulated market means product quality varies widely.
Common Side Effects
The most frequently reported side effects of CBD are drowsiness, diarrhea, fatigue, and decreased appetite. In FDA clinical trials of pharmaceutical-grade CBD, about 32% of participants experienced sleepiness or sedation (compared to 12% on placebo), 17% had diarrhea (versus 9% on placebo), and 21% reported decreased appetite (versus 5% on placebo). Most side effects across studies are rated as mild or moderate in severity.
These numbers come from trials using relatively high doses for epilepsy treatment, often 10 to 20 mg per kilogram of body weight per day. That translates to roughly 700 to 1,400 mg daily for a 150-pound person. Most people using CBD on their own take far less. One study of long-term, self-dosing CBD users found an average daily dose of about 53 mg, with a median around 41 mg. At these lower doses, side effects are less common and less intense.
Liver Health at High Doses
The most serious safety concern with CBD is its potential to affect the liver, particularly at high doses. In a clinical trial of 607 epilepsy patients taking CBD for 48 weeks, 10% showed elevated liver enzymes, a marker of liver stress. Importantly, 75% of those patients were also taking valproate, an anti-seizure drug known to be hard on the liver. None of these cases met the full criteria for drug-induced liver injury, and all patients recovered.
Higher doses tell a more concerning story. In a trial where healthy adults took 1,500 mg per day for about 3.5 weeks, 44% developed elevated liver enzymes, and 31% met criteria for drug-induced liver injury. A separate trial at the same dose found that 40% of participants had some degree of liver enzyme elevation during four weeks of use. In all cases, liver function returned to normal within one to two weeks after stopping CBD.
The risk of liver problems appears to be low at doses under 300 mg per day and increases significantly at 1,000 mg or above, especially when combined with other medications that affect the liver. If you take CBD regularly, periodic liver function testing is a reasonable precaution, particularly at higher doses.
Drug Interactions
CBD can interfere with how your body processes other medications. It does this by inhibiting certain liver enzymes responsible for breaking down drugs. The most affected enzyme pathway handles a wide range of common medications, including some blood thinners, anti-seizure drugs, and certain heart medications. When CBD blocks these enzymes, other drugs can build up in your system to higher-than-intended levels, increasing the risk of their side effects.
This interaction is especially relevant for people taking medications with a narrow margin between an effective dose and a harmful one. If you’re on prescription medications, particularly blood thinners or anti-seizure drugs, the interaction risk is real and worth discussing with your prescriber before starting CBD.
Product Quality Is Inconsistent
Because most CBD products are sold as supplements rather than pharmaceuticals, they aren’t subject to the same manufacturing standards or regulatory oversight. This creates two problems: you may not be getting what the label says, and the product may contain unwanted contaminants.
A 2022 study of 89 CBD topical products found that only 24% were accurately labeled. Fifty-eight percent contained more CBD than listed, and 18% contained less. While getting more CBD than expected might sound harmless, it means dosing is unpredictable, which matters if you’re trying to stay within a safe range or avoid interactions with other medications.
Contamination is another concern. An analysis of 202 CBD products in the U.S. found that 22% contained detectable levels of lead, the most commonly found heavy metal. Residual solvents from the extraction process were detected in 90% of products tested. Pesticides showed up in about 15% of products. While only a small percentage of these violated regulatory safety thresholds (3% for heavy metals, 1-9% for solvents and pesticides depending on the standard applied), the prevalence of detectable contaminants underscores the importance of choosing products that provide independent lab testing results.
How to Choose a Safer Product
Look for CBD products that provide a certificate of analysis (COA) from a third-party lab. This document should confirm the CBD and THC content matches the label and show test results for heavy metals, pesticides, and residual solvents. Products made from U.S.-grown hemp and manufactured by companies that follow good manufacturing practices tend to be more reliable, though this is not guaranteed.
Pregnancy and Breastfeeding
The FDA strongly advises against using CBD during pregnancy or while breastfeeding. There is no comprehensive research on CBD’s effects on a developing fetus or breastfed baby, but animal studies have shown that high doses of CBD caused problems with the reproductive system of developing male fetuses. CBD is also expected to transfer into breast milk. Combined with the contamination risks in unregulated products, the potential for harm outweighs any known benefit during pregnancy or nursing.
What “Safe” Looks Like in Practice
For a healthy adult not taking other medications, CBD at typical consumer doses (under 100 mg per day) carries a low risk of serious harm. The WHO found no significant effects on physiology or behavior in animals unless extremely high doses were given. CBD has no abuse potential, no evidence of recreational misuse, and no association with dependence.
The risks increase in specific situations: high doses above 300 mg daily, combined use with other medications (especially those processed by the liver), pregnancy, and use of poorly tested products. If you fall into any of these categories, the safety calculus shifts, and extra caution is warranted. For everyone else, the most practical steps are to start with a low dose, choose third-party tested products, and pay attention to how your body responds.