Cannabidiol (CBD)

    Written by:
    Kamal Patel
    Last Updated: August 28, 2025

    Like THC, CBD is a cannabinoid (a compound in cannabis). Unlike THC, CBD won’t get you high, but it shows promise as a treatment for epilepsy, anxiety, depression, pain, inflammation, cancer, and more. Unfortunately, as of 2022, human trials are still few.

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    126 references on this page
    2,333 participants in 16 trials and 1 meta-analysis

    Overview

    Dosage information

    The only CBD product approved in the U.S. is an epileptic drug: Epidiolex® is a solution (100 mg of CBD per milliliter) taken orally, preferably with food. The starting dosage is 2.5 mg per kilogram of body weight twice per day (so 5 mg/kg/day). The maximum dosage is 10 mg/kg twice per day (so 20 mg/kg/day). In people with hepatic impairment, the dosage is reduced.

    Since (i) dosages in studies are all over the place, (ii) a CBD product’s label will very often overstate or understate this product’s CBD content,[1][2] and (iii) high-fat and high-calorie meals can greatly increase CBD absorption,[3] properly dosing CBD products is very, very difficult.

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    Examine Database: Cannabidiol (CBD)

    Research FeedRead all studies

    Frequently asked questions

    Research Breakdown

    Examine Database References

    1. Depression Symptoms - Timo Woelfl, Cathrin Rohleder, Juliane K Mueller, Bettina Lange, Anne Reuter, Anna Maria Schmidt, Dagmar Koethe, Martin Hellmich, F Markus LewekeEffects of Cannabidiol and Delta-9-Tetrahydrocannabinol on Emotion, Cognition, and Attention: A Double-Blind, Placebo-Controlled, Randomized Experimental Trial in Healthy VolunteersFront Psychiatry.(2020 Nov 13)
    2. Anxiety Symptoms - Linares IM, Zuardi AW, Pereira LC, Queiroz RH, Mechoulam R, Guimarães FS, Crippa JACannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking testBraz J Psychiatry.(2019 Jan-Feb)
    3. Anxiety Symptoms - Hundal H, Lister R, Evans N, Antley A, Englund A, Murray RM, Freeman D, Morrison PDThe effects of cannabidiol on persecutory ideation and anxiety in a high trait paranoid groupJ Psychopharmacol.(2018 Mar)
    4. Schizophrenia symptoms - McGuire P, Robson P, Cubala WJ, Vasile D, Morrison PD, Barron R, Taylor A, Wright SCannabidiol (CBD) as an Adjunctive Therapy in Schizophrenia: A Multicenter Randomized Controlled TrialAm J Psychiatry.(2018 Mar 1)
    5. Schizophrenia symptoms - Boggs DL, Surti T, Gupta A, Gupta S, Niciu M, Pittman B, Schnakenberg Martin AM, Thurnauer H, Davies A, D'Souza DC, Ranganathan MThe effects of cannabidiol (CBD) on cognition and symptoms in outpatients with chronic schizophrenia a randomized placebo controlled trialPsychopharmacology (Berl).(2018 Jul)
    6. Crohn's Disease Symptoms - Naftali T, Mechulam R, Marii A, Gabay G, Stein A, Bronshtain M, Laish I, Benjaminov F, Konikoff FMLow-Dose Cannabidiol Is Safe but Not Effective in the Treatment for Crohn's Disease, a Randomized Controlled TrialDig Dis Sci.(2017 Jun)
    7. Anxiety Symptoms - Zuardi AW, Rodrigues NP, Silva AL, Bernardo SA, Hallak JEC, Guimarães FS, Crippa JASInverted U-Shaped Dose-Response Curve of the Anxiolytic Effect of Cannabidiol during Public Speaking in Real LifeFront Pharmacol.(2017 May 11)
    8. Anxiety Symptoms - Zuardi AW, Shirakawa I, Finkelfarb E, Karniol IGAction of cannabidiol on the anxiety and other effects produced by delta 9-THC in normal subjectsPsychopharmacology (Berl).(1982)
    9. Anxiety Symptoms - Zuardi AW, Cosme RA, Graeff FG, Guimarães FSEffects of ipsapirone and cannabidiol on human experimental anxietyJ Psychopharmacol.(1993 Jan)
    10. Ulcerative Colitis Symptoms - Irving PM, Iqbal T, Nwokolo C, Subramanian S, Bloom S, Prasad N, Hart A, Murray C, Lindsay JO, Taylor A, Barron R, Wright SA Randomized, Double-blind, Placebo-controlled, Parallel-group, Pilot Study of Cannabidiol-rich Botanical Extract in the Symptomatic Treatment of Ulcerative ColitisInflamm Bowel Dis.(2018 Mar 19)
    11. Seizure Frequency - Devinsky O, Patel AD, Cross JH, Villanueva V, Wirrell EC, Privitera M, Greenwood SM, Roberts C, Checketts D, VanLandingham KE, Zuberi SM, GWPCARE3 Study GroupEffect of Cannabidiol on Drop Seizures in the Lennox-Gastaut SyndromeN Engl J Med.(2018 May 17)
    12. Seizure Frequency - Devinsky O, Marsh E, Friedman D, Thiele E, Laux L, Sullivan J, Miller I, Flamini R, Wilfong A, Filloux F, Wong M, Tilton N, Bruno P, Bluvstein J, Hedlund J, Kamens R, Maclean J, Nangia S, Singhal NS, Wilson CA, Patel A, Cilio MRCannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trialLancet Neurol.(2016 Mar)
    13. Seizure Frequency - Hess EJ, Moody KA, Geffrey AL, Pollack SF, Skirvin LA, Bruno PL, Paolini JL, Thiele EACannabidiol as a new treatment for drug-resistant epilepsy in tuberous sclerosis complexEpilepsia.(2016 Oct)
    14. Seizure Frequency - de Oliveira VG, de Almeida NB, Radmann GC, de Oliveira Santos BFThe efficacy of cannabidiol for seizures reduction in pharmacoresistant epilepsy: a systematic review and meta-analysis.Acta Epileptol.(2025 Mar 17)
    15. Pain - Cuñetti L, Manzo L, Peyraube R, Arnaiz J, Curi L, Orihuela SChronic Pain Treatment With Cannabidiol in Kidney Transplant Patients in UruguayTransplant Proc.(2018 Mar)
    16. Pain - Palmieri B, Laurino C, Vadalà MShort-Term Efficacy of CBD-Enriched Hemp Oil in Girls with Dysautonomic Syndrome after Human Papillomavirus VaccinationIsr Med Assoc J.(2017 Feb)
    17. Pain - Wade DT, Robson P, House H, Makela P, Aram JA preliminary controlled study to determine whether whole-plant cannabis extracts can improve intractable neurogenic symptomsClin Rehabil.(2003 Feb)