There is no single agreed-upon daily limit for CBD. Regulatory agencies, clinical trials, and prescription medications all use wildly different numbers, ranging from 10 mg to over 1,500 mg per day. The right amount depends on why you’re taking it, what form you’re using, and whether you’re on other medications. Here’s what the evidence actually shows at each level.
What Regulators Recommend
The most conservative guideline comes from the UK’s Food Standards Agency, which in 2023 lowered its recommended daily limit from 70 mg to just 10 mg for CBD food supplements. That’s roughly four drops of a 5% CBD oil. The FSA set this limit based on concerns about long-term effects on the liver and thyroid, not because 10 mg is a proven effective dose for anything. In fact, the agency openly stated the new limit “has nothing to do with the effectiveness of the drug at this dose.”
The FDA in the United States hasn’t established a recommended daily amount for over-the-counter CBD products at all. The agency has repeatedly stated there are “many unanswered questions about the science, safety, and quality” of CBD products, and that long-term safety data in healthy people simply don’t exist yet. The longest study in healthy volunteers ran just 10 weeks.
What Clinical Trials Actually Use
Research doses bear almost no resemblance to the 10 mg regulatory suggestion. In anxiety studies, single doses of 300 to 600 mg have reduced anxiety in both healthy subjects and people with social anxiety disorder. Interestingly, the relationship between dose and effect isn’t straightforward: 300 mg and 600 mg reduced anxiety in some trials, while 150 mg and 900 mg did not. For sleep, one study used 300 mg dissolved in corn oil. Fear and stress studies have tested much smaller inhaled doses of 16 to 32 mg and found measurable effects.
At the high end, studies in healthy volunteers have tested 750 to 1,500 mg daily for six days. These doses were tolerable but came with significant side effects: 67% of participants experienced diarrhea (compared to 0% on placebo), 44% had headaches, and 17% reported dizziness.
Prescription CBD as a Reference Point
The only FDA-approved CBD product, used for severe epilepsy, offers a useful benchmark for high-dose safety under medical supervision. Patients typically start at 5 mg per kilogram of body weight per day and can go up to 20 or even 25 mg/kg/day. For a 70 kg (154 lb) adult, that translates to 350 mg up to 1,750 mg daily. These are among the highest doses studied with any rigor, and they require regular liver monitoring for good reason.
Where Liver Risk Begins
The most concrete safety concern with CBD is liver stress. In an FDA-conducted randomized trial, healthy participants took roughly 250 to 550 mg per day (based on body weight) for 28 days. About 5.6% of those on CBD developed liver enzyme elevations more than three times the normal upper limit, a standard marker for potential liver injury. Nearly 5% met the criteria for possible drug-induced liver damage.
The good news: none of those participants showed clinical symptoms of liver problems during the study, and their enzyme levels returned to normal within one to two weeks after stopping CBD. The elevations were dose-dependent, meaning higher doses carried more risk, and they typically appeared after about two weeks of daily use. Still, these were healthy adults taking pharmaceutical-grade CBD under controlled conditions, which is a very different situation from taking unregulated products long-term.
Why Your Dose May Not Match the Label
CBD is poorly absorbed when taken by mouth. Only about 6% of an oral dose reaches your bloodstream under typical conditions. Taking CBD with fatty foods improves absorption, but even then, only about a third of what you swallow makes it to the point where your body can use it. This is one reason clinical trials use such high milligram amounts to produce measurable effects, and why a 25 mg gummy and a 25 mg sublingual drop won’t necessarily feel the same.
Product quality adds another layer of uncertainty. Independent testing has repeatedly found that CBD products contain different amounts than what’s listed on the label. Some contain significantly less CBD, others significantly more, and some contain measurable THC. This makes it harder to dial in a consistent daily dose from consumer products compared to pharmaceutical-grade formulations used in studies.
CBD Can Change How Other Drugs Work
CBD inhibits several liver enzymes responsible for breaking down common medications, including those that process blood thinners, certain heart drugs, anti-seizure medications, and some antidepressants. This means CBD can cause other drugs to build up in your system to higher-than-intended levels, potentially increasing their side effects. The interaction risk grows with dose. If you take any prescription medications regularly, this is the most important safety factor to consider before adding CBD to your routine.
Practical Ranges for Daily Use
Pulling these threads together, the landscape looks roughly like this:
- Under 10 mg per day: The most conservative approach, aligned with UK food safety guidelines. Unlikely to produce noticeable effects based on available research, but also unlikely to cause harm.
- 10 to 50 mg per day: The range most consumer products suggest. Limited clinical evidence for effectiveness at these doses, though individual responses vary. Low risk of side effects for most people.
- 50 to 300 mg per day: The range where clinical trials begin to show effects on anxiety and sleep. Side effects like drowsiness and digestive upset become more likely. Drug interactions become a more serious consideration.
- 300 mg and above per day: Doses used in clinical research and prescription treatment. Liver enzyme monitoring is standard at these levels in medical settings. Diarrhea, fatigue, and appetite changes are common.
The gap between what regulators consider safe for unsupervised daily use (10 mg) and what clinical research uses to treat specific conditions (300 to 1,500 mg) is enormous. That gap exists because long-term safety data for healthy people taking moderate doses simply haven’t been collected yet. Most studies last a few days to a few weeks, and the FDA has noted that effects like weight changes can’t even be properly assessed in studies shorter than six months.
If you’re experimenting with CBD, starting low and increasing gradually gives you the best chance of finding the minimum effective dose while avoiding unnecessary side effects. Paying attention to what you take it with (food, other supplements, medications) matters as much as the milligram number on the bottle.