Last updated 28 August 2026.
CBD, short for cannabidiol, is one of the main substances made by the cannabis plant. It does not get you high, it is sold almost everywhere in oils, gummies, capsules and creams, and the claims made for it have run a long way ahead of what has actually been shown.
This page answers the questions people ask most, in plain language, and links to our reporting on each one. We have covered CBD since 2018. Where the evidence is good we say so. Where it is thin, or where a trial has been run and failed, we say that too.
Is CBD the same as THC?
No. THC is the part of cannabis that gets you high. CBD comes from the same plant and is closely related, but it does not produce that effect. Trials that gave people hundreds of milligrams of CBD found no intoxication and no meaningful effect on thinking.
That does not make CBD inert. It is an active substance that can make you drowsy, upset your stomach and interact with medicines. And “does not get you high” is not the same as “contains no THC”: full-spectrum products contain a little by design, which can matter for a drug test.
Does CBD get you high? The psychological effects of CBD, explained
What does “THC-free” really mean?
How long does CBD stay in your system?
Is hemp oil the same as CBD oil?
Usually not, and this catches a lot of people out. Hemp seed oil is pressed from the seeds. It is a cooking and cosmetic oil and contains little or no CBD. CBD oil is an extract from the flowers and leaves, mixed into a carrier oil, which is sometimes hemp seed oil. A product labelled “hemp oil” or “hemp extract” could be either. Look for the CBD content in milligrams; if it is not stated, assume there is none.
What’s the difference between hemp oil and CBD oil?
Origins of common cannabis terms
How does CBD work?
Your body makes its own cannabis-like signalling molecules, and has receptors for them, in a network that helps regulate sleep, appetite, pain and mood. THC works by plugging straight into the main receptor in that network. CBD does not. It seems to nudge several different systems a little, rather than one system a lot. That is why its effects are subtler than THC’s and much harder to pin down in a trial, and why the honest answer to “how does CBD work” is still “we are not sure”.
How CBD interacts with CB1 and CB2 receptors
CBD and serotonin: what the link really is
Endocannabinoid deficiency: the theory behind a lot of CBD marketing
Full spectrum, broad spectrum, isolate
These are marketing labels, not scientific ones, and manufacturers use them differently. Roughly: isolate is CBD on its own; broad spectrum keeps the other plant compounds but has the THC removed; full spectrum keeps everything, including a small amount of THC.
The idea that the whole plant works better than CBD alone is called the entourage effect. We lean towards full-spectrum products ourselves, but it is a hypothesis, not a finding. Two small human trials have tested pieces of it: one found a terpene reduced the anxiety THC can cause, the other found a different terpene did nothing for THC’s effect on memory.
CBD spectrums: choosing full spectrum, broad spectrum or isolate
A plain guide to cannabis terpenes
Cannabinoids explained: CBG, CBN, CBC and the minor cannabinoids
CBGA: the cannabinoid the others are made from
The product on the shelf is not the product in the trial
This is the most important thing on this page. When a study finds that CBD did something, it almost always used a lot of it. Anxiety trials used 300 to 600 mg. The prescription epilepsy medicine is dosed by body weight and runs to hundreds of milligrams a day for a child. A typical gummy or dropper serving is 10 to 25 mg.
Exercise recovery is the one area we know of where trial doses overlap with retail servings. Everywhere else, a shelf product is a fraction of what was tested, so a trial result does not tell you what a gummy will do. That is a reason for caution, not a reason to take more: the higher doses are where the side effects and drug interactions show up.
Two more things trip people up. The milligrams on the front of the bottle are usually the total in the bottle, not the amount per serving. And how you take it matters: swallowed CBD is mostly broken down before it reaches the blood, and taking it with a fatty meal can raise the amount absorbed several-fold. Holding drops under the tongue has not been shown to make a large difference.
How much CBD should you take?
CBD bioavailability: how much of your dose actually gets absorbed?
Ways to take CBD: which method actually works best?
CBD topicals vs other methods of administration
Do CBD patches actually work?
CBD skin cream and sublingual strips
What does CBD actually do? What the trials found
One use is settled: a prescription form of purified CBD reduces seizures in three rare epilepsies, and is licensed for that. Everything else is somewhere between promising and disproved. Here is the short version; each article has the detail.
Anxiety. Single large doses have calmed people before a stressful task in several trials, and one 12-week trial, funded by the manufacturer, found a benefit. But a 2026 review of 54 cannabinoid trials found no overall benefit for anxiety. It is the most promising area and still not established.
What research says about CBD and anxiety
Sleep. CBD is not a sedative. The one proper trial in people with insomnia, at 150 mg a night, found no improvement in the main measures. Where it helps, it may be by easing anxiety or discomfort. CBN, the cannabinoid sold for sleep, has a handful of small, mostly industry-funded trials with mixed results.
Does CBD actually help you sleep?
Does CBD make you tired?
CBN and sleep: how does CBN help with sleep?
CBD vs CBN: what’s the difference?
Pain. Most trials of CBD on its own have found nothing. One 2026 trial, at very high doses, helped nerve pain after spinal cord injury. Cannabis medicines that contain THC have the better evidence, and for migraine the trial that tested them head to head found a THC-and-CBD combination beat placebo while CBD alone did not. For arthritis, three oral trials failed; a small trial of a rub-on cream was positive.
CBD oil for pain: can it really help?
CBD for arthritis: what the trials actually found
Headaches and chronic migraines: can CBD help?
CBD and chronic pain: a pain doctor’s perspective
Exercise recovery. Small trials at 17 to 67 mg found people felt less sore; other trials, including three of creams, found nothing. Nobody has shown CBD speeds muscle repair. If you compete, note that CBD is the only cannabinoid not banned in sport.
CBD for exercise recovery: what the evidence shows
Skin. CBD does not pass through skin easily, so the product’s formulation matters more than the CBD. A purpose-built acne gel failed its main test. Cosmetics are mostly untested. Rinse-off products like shampoo have almost no case; bath bombs less.
Does CBD work on your skin?
CBD shampoos, mascara and bath bombs: do they work?
CBD for your scalp: what the studies actually show
Can CBD help a sunburn?
Other conditions. Epilepsy is the success story. For multiple sclerosis, a THC-and-CBD spray is licensed in many countries; CBD alone has nothing comparable. In Parkinson’s, most trials of CBD were negative. In PTSD, no cannabis preparation beat placebo in the one randomised trial. One trial found CBD lowered blood pressure a little, using a special absorption-enhanced formulation, and taking more did not lower it further.
CBD and seizures: what the evidence shows
CBD for multiple sclerosis: what the evidence shows
CBD and Parkinson’s disease: what the trials show
CBD and PTSD: why patients and trials disagree
CBD and blood pressure
Is CBG the new CBD?
Pets. The best evidence in dogs is for seizures. Arthritis results are mixed and anxiety evidence is preliminary. Never give a dog a product made for people without checking the ingredients: some contain xylitol, which is poisonous to dogs, and dogs are far more sensitive to THC than we are.
CBD for dogs: what the veterinary evidence shows
Is CBD safe?
Mostly, at the doses people usually take. The common side effects are drowsiness, diarrhoea and changes in appetite. At high doses, several hundred milligrams a day and up, some people’s liver enzymes rise, which is why the prescription medicine comes with blood tests. In the largest review we know of, no adult case was reported below 300 mg a day.
The bigger risk is medicines. CBD is broken down by the same liver enzymes that handle many prescription drugs, and it can push their levels up. The clearest evidence is for a common epilepsy drug and for the antidepressant citalopram. Spacing the doses apart does not fix this. If you take a prescription, ask a pharmacist before adding CBD.
If you are pregnant or breastfeeding, the advice from every health authority is not to use it, because the safety data does not exist. The same goes for children unless a doctor is directing it.
CBD and drug interactions
Does CBD cause liver damage?
Can CBD oil be used during pregnancy?
Is it safe to use CBD while breastfeeding?
CBD for women with endometriosis
How do I know what I’m buying?
You often don’t. In the testing studies we have reviewed, most products were off their labelled CBD content by more than 10%, and some contained THC they were not supposed to. The best tool you have is a certificate of analysis: a lab report for the batch in your hand, from an independent lab, dated recently, showing CBD and THC per serving and screening for pesticides, metals and solvents. If a brand can’t show you one, buy from one that can.
How to read a CBD certificate of analysis
Is CBD legal?
In the United States, hemp-derived CBD has been legal at the federal level since 2018, defined as cannabis with no more than 0.3% THC. That definition is about to change. A law passed in November 2025 counts all forms of THC, including THCA, and caps hemp-derived products at 0.4 mg per container. It now takes effect on 11 December 2026 — a one-month delay was signed into law in early September — except for lab-made cannabinoids like commercial delta-8, which are cut off on 12 November. It will affect many full-spectrum products.
Separately, the FDA has never accepted CBD as a food or supplement ingredient, and in 2023 asked Congress to create a new set of rules for it. That has not happened yet. So the market is legal on the hemp question and unresolved on the product question, and enforcement has mostly targeted disease claims and products aimed at children. Outside the US the rules vary widely; check your own country’s.
The November 2026 hemp law change: what it means for CBD
Nothing on this page is medical advice. If you have a diagnosed condition, take prescription medicine, are pregnant or breastfeeding, or are thinking about CBD for a child or an animal, talk to a doctor, pharmacist or vet first.