CBD Isolate
Also known as Pure CBD, Cannabidiol isolate, Crystalline CBD
Purified, THC-free cannabidiol in crystalline form; shares CBD Oil's proposed anxiety-relieving and anti-inflammatory mechanisms without whole-plant entourage compounds, psychoactive effects, or most legal restrictions.
Reported side effects:Somnolence and sedation — 29% of Epidyolex-treated patients across controlled trials (43% with concomitant clobazam vs 14% without); more common early in treatment and may diminish with continued treatmentDecreased appetite; dose-related diarrhoea (first onset typically within the first 6 weeks); vomiting; pyrexia; fatigueNausea; irritability and aggression; lethargy; rash; weight decrease (dose-related; 21% at 20-25 mg/kg/day had >=5% weight loss)
Be careful if: certain health conditions, pregnant, breastfeeding, some medical situations
Ask first if you take: epilepsy medicines (antiepileptics), sedatives or sleep medicines, immunosuppressants, other medicines
Suspect a side effect? Report it to the MHRA Yellow Card scheme ↗
What the research actually shows
We link to relevant studies and leave interpretation to you and your healthcare professional.
Safety and considerations
What sources report about side effects, who should be careful, and medicines to ask about first.
Reported side effects
| Reported effect | How often | Basis | Sources |
|---|---|---|---|
| Somnolence and sedation — 29% of Epidyolex-treated patients across controlled trials (43% with concomitant clobazam vs 14% without); more common early in treatment and may diminish with continued treatment | very common | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| Decreased appetite; dose-related diarrhoea (first onset typically within the first 6 weeks); vomiting; pyrexia; fatigue | very common | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| Nausea; irritability and aggression; lethargy; rash; weight decrease (dose-related; 21% at 20-25 mg/kg/day had >=5% weight loss) | common | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| Laboratory changes in trials: small mean decreases in haemoglobin and haematocrit, and a ~10% serum creatinine increase within 2 weeks of starting (mechanism undetermined; reversible in healthy adults) | unknown | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
Serious effects reported
| Reported effect | How often | Basis | Sources |
|---|---|---|---|
| Dose-related liver-enzyme (ALT/AST) elevations — ALT >3x upper limit of normal in 12% of Epidyolex-treated patients vs <1% placebo; 23% with concomitant valproate and clobazam, 19% valproate alone, 3% neither. The SmPC defines transaminase/bilirubin monitoring and discontinuation thresholds; transaminase elevation was the most frequent cause of discontinuation. | common | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| Suicidal behaviour and ideation — class warning for anti-epileptic drugs (meta-analysis of placebo-controlled trials shows a small increased risk); monitoring advised | unknown | Listed by UK SmPC (emc / MHRA) | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
Be careful if you…
| Applies to | What sources say | Sources |
|---|---|---|
| certain health conditions | Contraindicated with transaminases >3x ULN and bilirubin >2x ULN. Baseline and scheduled serum transaminase/bilirubin monitoring is required (routine: 1, 3 and 6 months; intensified with valproate or baseline elevations); treatment stopped above defined thresholds (SmPC 4.3/4.4). NHS: doctors monitor liver function during CBD treatment. | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022 |
| pregnant | Should not be used during pregnancy unless the potential benefit clearly outweighs the risk — limited human data and animal studies have shown reproductive toxicity (SmPC 4.6). | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| breastfeeding | As a precaution, breastfeeding should be discontinued during treatment — no human data on excretion into milk, and cannabidiol is expected to pass into milk (SmPC 4.6). | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| some medical situations | UK regulatory position: purified CBD (Epidyolex) is a prescription medicine initiated by epilepsy specialists for specified syndromes; food-supplement CBD is regulated by the FSA as a novel food, whose consumer advice is not to exceed 70 mg/day from food supplements, and MHRA classifies CBD products with medicinal claims as medicines. NHS notes there is no certainty over the quality or CBD content of shop-bought CBD products. | Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022Cannabidiol (CBD) guidance — FSA business guidance on CBD as a novel food, GOV.UK, last updated 28 August 2026MHRA statement on products containing cannabidiol (CBD), GOV.UK, published 14 April 2025 |
Medicines to ask about
| Severity | Medicine | Sources |
|---|---|---|
| ask first | epilepsy medicines (antiepileptics) — Clobazam: bi-directional interaction — 3-4x N-desmethylclobazam (CYP2C19) with more somnolence/sedation; clobazam dose reduction considered. Valproate: more transaminase elevations, diarrhoea and decreased appetite. Phenytoin (CYP2C9, narrow index): exposure may increase — initiate with caution. Lamotrigine (UGT2B7): levels may be elevated. Stiripentol: exposure increased ~17-55%. Carbamazepine and other strong CYP3A4/2C19 inducers reduce cannabidiol levels (SmPC 4.5). | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022 |
| caution | sedatives or sleep medicines — Other CNS depressants, including alcohol, can potentiate somnolence and sedation (SmPC 4.4). | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| caution | immunosuppressants — Everolimus coadministration increased everolimus exposure; patients closely monitored for adverse reactions (SmPC 4.5). | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
| caution | other medicines — Cannabidiol is a UGT1A7/1A9/2B7 substrate — caution with drugs inhibiting these UGTs (no formal interaction studies; dose reduction of either may be necessary) (SmPC 4.5). FLAG for Joe: no fixed medicine class exists for 'UGT inhibitors' — kept under 'other' per schema rule. | Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026 |
How much is too much
When and how to take it
| Guidance | Detail |
|---|---|
| Take | with or without food |
| Avoid with | alcohol — Alcohol and other CNS depressants can potentiate the somnolence and sedation effect (SmPC 4.4). |
Sources
Epidyolex 100 mg/ml oral solution SmPC, emc, updated 18-Jun-2026Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022Cannabidiol (CBD) guidance — FSA business guidance on CBD as a novel food, GOV.UK, last updated 28 August 2026MHRA statement on products containing cannabidiol (CBD), GOV.UK, published 14 April 2025
Suggested uses (unproven)
Where people report using it and what trials suggest
- Strong evidenceEpilepsy (purified CBD, Rx dosing)
- Mixed evidenceAnxiety (acute dosing)
Where the evidence is negative
Common claims the trials do not support
- 'Isolate vs broad-spectrum' superiority claims are marketing — head-to-head human data absent.
- Consumer isolates typically dosed far below the 10-20 mg/kg used in trials.
- Pain and insomnia evidence weak.
Purified CBD (>99%). Same active molecule as prescription Epidiolex; isolate products still face the mislabelling and dosing-consistency issues of the consumer market.
Evidence grades reflect study quality and consistency, not marketing claims.
Ordered by strength of evidence, then result direction.
01Cannabidiol Use in Developmental and Epileptic Encephalopathies: A Syndrome- and Age-Stratified Systematic Review and Meta-analysisde Oliveira HM, et al. · CNS drugs · 2026PMID 42185726 ↗02Effects of Different Cannabinoid Formulations on Anxiety-Related Disorders, and Tourette Syndrome: A Systematic Review and Meta-AnalysisRaminelli AO, et al. · Cannabis and cannabinoid research · 2025PMID 40956670 ↗03Medicinal cannabis for psychiatric disorders: a clinically-focused systematic reviewSarris J, et al. · BMC psychiatry · 2020PMID 31948424 ↗04Biological effects of Cannabidiol on normal human healthy cell populations: Systematic review of the literaturePagano S, et al. · Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie · 2020PMID 33038581 ↗05Aplicaciones terapéuticas por acción de los cannabinoidesPlancarte-Sánchez R, et al. · Gaceta medica de Mexico · 2019PMID 31219471 ↗06Comparative Pharmacokinetics and Safety of Cannabidiol in a Powder Formulation, CBtru(®), vs an Oil-Based Formulation, Epidyolex(®), Under Fasted and Fed Conditions in Healthy Participants: A Randomized Open-Label Cross-Over Phase I StudyBendik I, et al. · CNS drugs · 2026PMID 41888503 ↗Show all 18 studies
Published research summaries are unavailable.
What publications report
Outcome rows from the linked papers’ curated records. Educational, not medical advice. Ordered by strength of evidence, then result direction.
Reduced in 79.2% of patients within the first month
Adults with anxiety and sleep concerns · Case series · PMID 30624194 ↗Weak evidenceReduced02Sleep — ImprovedImproved in 66.7% within the first month
Adults with anxiety and sleep concerns · Case series · PMID 30624194 ↗Weak evidenceImprovedFigures are reported as published; designs and populations vary. We do not interpret results or give medical advice.
Why people look into CBD Isolate — and what they report
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
Where to get CBD Isolate (UK)
How this compound is sold in the UK, and where our readers typically find it.
Retailer search links — we may earn commission on purchases at no cost to you. Commission never affects our evidence ratings.
In the UK, CBD products fall under the FSA novel foods list — buy from retailers listing an FSA-assessed product.