CBD Simply Explained

1. What Is CBD (Cannabidiol)?

Cannabidiol, or CBD for short, is a substance from the hemp plant. Unlike THC, it does not intoxicate. It is the active ingredient of approved medicines for certain forms of epilepsy. It is also offered in oils, capsules, and skin products. It is being investigated for anxiety, sleep, and pain, among other things.

2. Where Is It Found, and What Is It Made From?

CBD forms in the flowers and resin of the hemp plant. It is especially abundant in cultivated varieties with low THC content, so-called industrial hemp. It is obtained by extraction from hemp flowers, usually with carbon dioxide or alcohol. The extract is diluted in edible oil or purified to pure CBD. Hemp seed oil from the seeds contains practically no CBD.

3. What Does CBD (Cannabidiol) Do? What Research Shows

Pain

For pain, the picture is mixed. In acute toothache, a single oral dose relieved pain more than a substance-free product 35. After shoulder surgery, pain was lower only on the first day 30. In knee osteoarthritis, after ureteroscopy, and in nerve pain from chemotherapy, no advantage was shown 323340. Small studies with preparations for application reported less pain 373846.

Anxiety

For anxiety, the picture is mixed. One review considers anxiety reduction possible, but the individual results contradict each other 21. Another describes anxiolytic effects especially after a single dose 8. Several controlled studies (with a comparison group), by contrast, found no difference from a substance-free product 2939424344. It remains open which dose, purity, and treatment duration are decisive for a possible benefit.

Epilepsy

For epilepsy the situation is clearest. In severe epilepsies that usually begin in childhood, CBD as an oral solution reduced seizures more than a substance-free agent 71122. Slightly more patients became seizure-free 27. What was studied above all was a highly purified solution as an add-on to standard treatment. The preparation is called Epidiolex, in Europe Epidyolex, and is approved for Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis. Side effects were more frequent than with a substance-free agent 112223.

Addiction

In addiction disorders, CBD brought no advantage over a substance-free product in several controlled studies 394144. Only drug cue-induced craving decreased in a small study 51. The studies are small and short. Information on dose, purity, and accompanying treatment is often missing.

Psychosis

In psychosis and schizophrenia, the picture is mixed. Two reviews see evidence of an effect against the disease 819. A third mentions promising preliminary findings 25. One review, by contrast, found no superiority in schizophrenia 26. A controlled study in bipolar depression found no difference in psychotic symptoms 42. The controlled studies are small and short. Form, dose, and purity are often not reported.

Skin

For the skin, the evidence is limited. A controlled study with oral CBD oil found no improvement in psoriasis, but less itching 47. A small study with a cream showed less thickening of the epidermis after UV-A irradiation 49. Less redness was seen only in a subset of participants. The studies are small and short. For most skin conditions, robust data are lacking.

Sleep

For sleep, there are many, mostly small and short studies. The results are mixed. Sleep quality improved in two small controlled studies 3648. In insomnia, two controlled studies found no difference from a substance-free product 4554. One review found no effect on sleep quality for CBD alone 6. Form, dose, and purity of the tested preparations vary greatly.

Other Investigations

Further studies concern very different questions. In high blood pressure, oral CBD lowered blood pressure more than a substance-free product in two controlled studies 3450. In gum inflammation, inflammation values improved in a controlled study 31. For body weight, the findings are inconsistent 2452. Under oral CBD, more adverse effects occurred than under a substance-free product 72227. Liver values rose more frequently in several controlled studies 72833.

4. How Was CBD (Cannabidiol) Taken in the Studies?

In the studies, what was tested above all were oral solutions, oil drops, capsules and tablets. In addition there were individual skin products for application. In epilepsy, a highly purified oral solution as an add-on to standard treatment was predominantly studied. Individual investigations used forms for inhalation or for application. The form, dose and purity of the CBD differed greatly between the studies.

5. Is CBD (Cannabidiol) Safe? Side Effects in the Studies

CBD can have adverse effects. Common were diarrhea, drowsiness, loss of appetite, and elevated liver values 92223. In other studies, the adverse effects did not differ from a substance-free product 54453. Elevated liver values and drowsiness occurred mainly with simultaneous intake of the epilepsy medicines valproate or clobazam 59. If a preparation contains other cannabinoids or terpenes in addition to CBD, the effect cannot be attributed to CBD alone. Robust information on dose, duration, and long-term benefit is often lacking.

All details with tables and sources: full expert page on CBD (cannabidiol)