CBD, short for cannabidiol, is a compound found in cannabis plants that interacts with your body’s endocannabinoid system and several other receptor pathways to produce a range of effects. It does not cause a high. Instead, it influences pain signaling, stress responses, inflammation, and neurological activity in ways that vary significantly depending on how much you take and how you take it.
How CBD Affects Your Body
CBD works differently from THC, the compound in cannabis that produces intoxication. Rather than binding directly to cannabinoid receptors in the brain, CBD influences them indirectly and also activates serotonin receptors involved in mood regulation, vanilloid receptors involved in pain perception, and several other targets throughout the nervous system. This wide range of activity is why CBD shows up in research on everything from anxiety to epilepsy to chronic pain.
One important quirk of CBD is that its effects follow an inverted U-shaped curve. In a well-known public speaking anxiety study, 300 mg significantly reduced anxiety compared to placebo, but 150 mg and 600 mg did not. The likely explanation: at higher doses, CBD activates a receptor that increases the release of an excitatory brain chemical called glutamate, which can counteract the calming effects seen at moderate doses. This means more is not always better.
Anxiety and Stress Reduction
Anxiety reduction is the most consistently supported effect of CBD in clinical trials. Across multiple studies, oral doses of 300 to 400 mg reduced self-reported anxiety in healthy volunteers exposed to stressful situations and in people diagnosed with social anxiety disorder. A four-week trial of 300 mg daily reduced anxiety in people with social anxiety compared to placebo. Healthcare workers taking 300 mg daily during the COVID pandemic showed reduced emotional exhaustion and burnout symptoms.
These are considerably higher doses than what most over-the-counter CBD products suggest. A typical gummy or tincture serving contains 10 to 50 mg, which is a fraction of the doses studied in clinical settings. That gap between retail products and research doses is one of the biggest sources of confusion around CBD.
Pain and Inflammation
For chronic pain, the evidence is less encouraging. Small clinical trials using relatively low doses (averaging about 2.4 mg per kilogram of body weight per day) found no significant improvement in conditions like chronic neuropathic pain or Crohn’s disease. For a 150-pound person, that average dose would be around 165 mg per day. Researchers have noted that these doses were quite low compared to what’s used in other CBD studies, which leaves open the question of whether higher doses might perform differently. But as of now, there’s no strong clinical trial evidence that CBD reliably reduces chronic pain in humans at commonly available doses.
Sleep Effects
Many people take CBD hoping it will help them sleep, but controlled research tells a more nuanced story. A randomized trial testing 150 mg of CBD nightly against placebo in people with moderate to severe insomnia found no significant difference in how quickly people fell asleep, how long they stayed asleep, or how often they woke up during the night. The CBD group did report greater overall well-being and showed slightly better objective sleep efficiency after two weeks, suggesting the benefit may be more about feeling calmer than about directly inducing sleep. Higher doses and longer treatment periods might produce different results, but that hasn’t been confirmed yet.
Epilepsy: The One FDA-Approved Use
The clearest medical application of CBD is in treating certain severe forms of epilepsy. The FDA approved a pharmaceutical-grade CBD oral solution for this purpose, with a recommended starting dose of 5 mg per kilogram of body weight per day, increasing to a maintenance dose of 10 mg/kg/day. For a 70-pound child, that maintenance dose works out to roughly 320 mg daily. These are prescription-level doses administered under medical supervision, far higher than what’s found in consumer products.
How Delivery Method Changes the Dose
The way you consume CBD dramatically affects how much actually reaches your bloodstream. When you swallow CBD in a capsule, gummy, or oil, only about 6 to 14% of it is absorbed. Your digestive system and liver break down the rest before it can circulate. Inhaled CBD (through vaping or smoking) reaches roughly 31% bioavailability, meaning nearly three times as much enters your system compared to swallowing the same amount. Taking CBD with fatty foods can improve oral absorption because CBD is fat-soluble and dissolves more readily when consumed alongside lipids.
This is why a 30 mg inhaled dose can feel noticeably different from a 30 mg edible. Timing varies too: inhaled CBD reaches peak blood levels within minutes, while oral CBD takes anywhere from one to four hours. After chronic oral use, CBD can linger in the body with a half-life of two to five days, meaning it builds up over time with regular dosing.
Drug Interactions
CBD inhibits several liver enzymes responsible for metabolizing common medications. At a dose of 640 mg, CBD increased blood levels of a common acid reflux drug by 207%, a blood pressure medication by 77%, and a sedative by 56%. Modeling research predicted that even doses as low as 20 mg twice daily could meaningfully alter how your body processes drugs broken down by certain liver enzymes. The threshold to avoid any interaction at all was estimated at just 5 mg twice daily.
This matters if you take blood thinners, anti-seizure medications, certain antidepressants, or other drugs processed through the same liver pathways. CBD can effectively increase the dose of those medications by slowing their breakdown, raising the risk of side effects.
Safety and Liver Effects
At prescription-level doses up to 25 mg/kg/day, CBD carries a measurable risk of liver stress. In a clinical trial where participants took 250 to 550 mg daily for 28 days, about 5.6% developed elevated liver enzymes exceeding three times the normal upper limit. Nearly 5% met criteria for potential drug-induced liver injury. These effects were observed at doses well above what most consumers take, but they establish that CBD is not without risk at higher amounts.
Most people taking retail-level doses (under 100 mg/day) report mild or no side effects. When side effects do occur, they typically include changes in appetite, mild nausea, or gastrointestinal discomfort.
Finding the Right Dose
There is no universal CBD dose because the effective amount depends on what you’re trying to address, your body weight, your delivery method, and individual variation in metabolism. Clinical research has used doses ranging from 20 mg/day to over 1,000 mg/day depending on the condition. For anxiety, the sweet spot in studies has consistently landed around 300 mg orally, though this is higher than what most people start with.
A common starting approach is 20 to 40 mg per day, increasing by 5 mg per week until you notice an effect or reach a dose you’re comfortable with. Because oral bioavailability is so low, the numbers on the label don’t reflect what your body actually uses. Taking CBD with a meal containing some fat can meaningfully boost absorption. If you take any other medications, the interaction risk is real and worth discussing with a pharmacist who can check your specific drug list against CBD’s enzyme effects.