- Pain severity and treatment responseReported a benefitmeasurement not reportedSynthetic high THC products may moderately improve pain severity and response versus placebo in 1740 people over 1 to 6 months.1 review of trials2022 study ↗
botanical
Cannabis (THC)
Also known as THC, Delta-9-tetrahydrocannabinol, Marijuana, Cannabis sativa
Delta-9-tetrahydrocannabinol, the primary psychoactive cannabinoid in Cannabis sativa, acting as a partial agonist at CB1 receptors; used medically for chronic pain, chemotherapy-induced nausea, appetite stimulation, and spasticity. Subject to legal restrictions varying by jurisdiction.
Reported side effects:Dizziness (Sativex SmPC: the most commonly reported reaction, mainly during initial dose titration; usually mild to moderate and resolving within days even with continued treatment)Fatigue / astheniaSomnolence, attention disturbance, balance disorder, memory impairment, disorientation, dissociation, euphoric or depressed mood
Be careful if: certain health conditions, pregnant, breastfeeding, some medical situations
Ask first if you take: sedatives or sleep medicines, contraceptives or HRT, other medicines
Suspect a side effect? Report it to the MHRA Yellow Card scheme ↗
5linked conditions
31linked studies
Evidence
What the research actually shows
We link to relevant studies and leave interpretation to you and your healthcare professional.
What studies found
The headline results, condition by condition
The large figures are what the studies reported for each thing they measured. Open a card for every result.
Colour keyReported a benefitNo clear benefitUnclearPossible harmAmber is for highlights, such as where the most research is. It never means a result was good.
Safety
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 |
|---|---|---|---|
| Dizziness (Sativex SmPC: the most commonly reported reaction, mainly during initial dose titration; usually mild to moderate and resolving within days even with continued treatment) | very common | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Fatigue / asthenia | very common | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Somnolence, attention disturbance, balance disorder, memory impairment, disorientation, dissociation, euphoric or depressed mood | common | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Nausea, diarrhoea, dry mouth, vomiting, constipation; application-site reactions (oral pain, mouth ulceration, oral discomfort, taste disturbance) | common | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Palpitations, tachycardia, hypertension; blurred vision, vertigo | common | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
Serious effects reported
| Reported effect | How often | Basis | Sources |
|---|---|---|---|
| Neuropsychiatric reactions — hallucinations, paranoia, delusional perceptions, illusions and transient psychotic reactions reported; treatment should be stopped immediately and the patient monitored until symptoms resolve. In a supratherapeutic dosing study, 3 of 41 subjects at 18 sprays twice daily experienced transient toxic psychosis. | uncommon | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Suicidal ideation — in a few cases a causal association with Sativex could not be ruled out | uncommon | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| Falls — increased incidence possible when reduced spasticity outpaces muscle strength, with additive risk alongside CNS adverse reactions | unknown | Listed by UK SmPC (emc / MHRA) | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
Be careful if you…
| Applies to | What sources say | Sources |
|---|---|---|
| certain health conditions | Contraindicated in patients with any known or suspected personal or family history of schizophrenia or other psychotic illness, or history of severe personality disorder or other significant psychiatric disorder (SmPC 4.3). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| certain health conditions | Not recommended in patients with serious cardiovascular disease — alterations in pulse rate and blood pressure observed at initiation and fainting episodes reported; caution during initial titration. Caution in patients with a history of epilepsy or recurrent seizures (SmPC 4.4). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| pregnant | Should not be used during pregnancy unless the potential risks are clearly outweighed by the benefit; men and women of childbearing potential should use reliable contraception during therapy and for three months after stopping (SmPC 4.4/4.6). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| breastfeeding | Contraindicated during breastfeeding — cannabinoids are excreted in milk in animals and a risk to the breastfed child cannot be excluded (SmPC 4.3/4.6). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| some medical situations | UK legal status: cannabis and THC are Class B controlled substances; possession is unlawful without a prescription, prescribing is specialist-only, and it is an offence to drive while under the influence (statutory defence only when taken as prescribed and not impairing driving) — NHS and SmPC 4.7 (Road Traffic Act 1988 section 5A). | Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| some medical situations | Patients with a history of substance abuse may be more prone to misuse; abrupt withdrawal of long-term treatment may cause transient disturbances of sleep, emotion or appetite (SmPC 4.4). NHS notes evidence that regular cannabis use in some people can increase the risk of psychotic illness and that dependency risk is probably small under specialist control. | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026Medical cannabis (and cannabis oils) — NHS medicines page, last reviewed 27 May 2022 |
Medicines to ask about
| Severity | Medicine | Sources |
|---|---|---|
| caution | sedatives or sleep medicines — Additive sedation and muscle relaxation with hypnotics, sedatives and drugs with potential sedating effects; benzodiazepines and baclofen theoretical additive fall risk (SmPC 4.5). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| ask first | contraceptives or HRT — Sativex may reduce the effectiveness of hormonal contraceptives; women of childbearing potential must use reliable contraception, with an additional barrier method during therapy and for three months after (SmPC 4.4/4.5/4.6). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
| ask first | other medicines — Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin) increased THC and CBD exposure up to ~2-3.6-fold; strong CYP2C9 inhibitors (fluconazole) increased THC and 11-OH-THC exposure; strong enzyme inducers (rifampicin, carbamazepine, phenytoin, phenobarbital, St John's Wort) reduced exposure markedly and should be avoided when possible (SmPC 4.5). | Sativex (nabiximols) 27 mg/ml oromucosal spray SmPC, emc, updated 14-Jul-2026 |
How much is too much
When and how to take it
| Guidance | Detail |
|---|---|
| Avoid with | sedatives sleep medicines — Additive sedation and muscle relaxation; patients warned of this possibility (SmPC 4.4/4.5). |
Evidence analytics
Where the evidence is concentrated
Audited published research for Cannabis (THC) by condition. Drill into a pair page for the full breakdown.
Cannabis (THC): findings by condition
What this means: Bars count reported findings, not treatment effectiveness or certainty.
One study may report several findings or appear in more than one pairing. Counts do not show the size of an effect. Comparable numerical estimates are not established for this summary.
View the full data table
| Compound and condition | Findings (count) | Studies (count) | Reported results (finding counts) | How sure? |
|---|---|---|---|---|
| Chronic Pain | 4 | 1 | Benefit: 1; no benefit: 0; harm: 3; unclear: 0; not recorded / unrecognised: 0 | Not formally graded |
Suggested uses (unproven)
Where people report using it and what trials suggest
- Strong evidenceChemotherapy-induced nausea (Rx cannabinoids)
- Strong evidenceMS spasticity (Rx, nabiximols)
- Moderate evidenceChronic neuropathic pain adjunct
Where the evidence is negative
Common claims the trials do not support
- For most chronic-pain conditions, guideline reviews find small/unreliable benefits vs harms.
- Anxiety relief paradox: acute anxiolysis at low dose, anxiogenic and panic-inducing at higher doses/naive users.
- Chronic use: dependence (~10%), cognitive impairment, psychosis risk in predisposed.
- Depression and PTSD trials largely null.
Δ9-THC has real prescription indications (chemo nausea, spasticity, appetite in HIV/AIDS) alongside well-documented harms from recreational use.
Evidence grades reflect study quality and consistency, not marketing claims.
31studies referenced
28journals
2014–2026publication range
Ordered by strength of evidence, then result direction.
01Cannabis-Based Products for Chronic Pain : An Updated Systematic ReviewChou R, et al. · Annals of internal medicine · 2026PMID 41429020 ↗02The effects of oral cannabidiol supplementation on blood pressure in adults: a systematic review of randomised controlled trialsRoberts A, et al. · Journal of cannabis research · 2026PMID 42321899 ↗03Effectiveness of Cannabidiol to Manage Chronic Pain: A Systematic ReviewMohammed SYM, et al. · Pain management nursing : official journal of the American Society of Pain Management Nurses · 2024PMID 37953193 ↗04Cannabis and Cannabinoids in Adults With Cancer: ASCO GuidelineBraun IM, et al. · Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2024PMID 38478773 ↗05Evidence-Based Treatment of Pain in Chemotherapy-Induced Peripheral NeuropathyD'Souza RS, et al. · Current pain and headache reports · 2023PMID 37058254 ↗06Cannabis-based medicines and medical cannabis for adults with cancer painHäuser W, et al. · The Cochrane database of systematic reviews · 2023PMID 37283486 ↗Show all 31 studies
07Balancing risks and benefits of cannabis use: umbrella review of meta-analyses of randomised controlled trials and observational studiesSolmi M, et al. · BMJ (Clinical research ed.) · 2023PMID 37648266 ↗08Cannabis and cannabinoid use in autism spectrum disorder: a systematic reviewSilva EAD Junior, et al. · Trends in psychiatry and psychotherapy · 2022PMID 34043900 ↗09Age at onset of mental disorders worldwide: large-scale meta-analysis of 192 epidemiological studiesSolmi M, et al. · Molecular psychiatry · 2022PMID 34079068 ↗10A Systematic Review on Cannabis Hyperemesis Syndrome and Its Management OptionsSenderovich H, et al. · Medical principles and practice : international journal of the Kuwait University, Health Science Centre · 2022PMID 34724666 ↗11Effects of Cannabis in Parkinson's Disease: A Systematic Review and Meta-AnalysisUrbi B, et al. · Journal of Parkinson's disease · 2022PMID 34958046 ↗12Cannabis-Based Products for Chronic Pain : A Systematic ReviewMcDonagh MS, et al. · Annals of internal medicine · 2022PMID 35667066 ↗13Medical Cannabis for the Treatment of Migraine in Adults: A Review of the EvidenceOkusanya BO, et al. · Frontiers in neurology · 2022PMID 35711271 ↗14Medical cannabinoids: a pharmacology-based systematic review and meta-analysis for all relevant medical indicationsBilbao A, et al. · BMC medicine · 2022PMID 35982439 ↗15Impact of COVID-19 on Mental Health in Adolescents: A Systematic ReviewJones EAK, et al. · International journal of environmental research and public health · 2021PMID 33802278 ↗16Approved cannabinoids for medical purposes - Comparative systematic review and meta-analysis for sleep and appetiteSpanagel R, et al. · Neuropharmacology · 2021PMID 34181977 ↗17Medical cannabis or cannabinoids for chronic non-cancer and cancer related pain: a systematic review and meta-analysis of randomised clinical trialsWang L, et al. · BMJ (Clinical research ed.) · 2021PMID 34497047 ↗18Medicinal cannabis for psychiatric disorders: a clinically-focused systematic reviewSarris J, et al. · BMC psychiatry · 2020PMID 31948424 ↗19Association of Cannabis Use in Adolescence and Risk of Depression, Anxiety, and Suicidality in Young Adulthood: A Systematic Review and Meta-analysisGobbi G, et al. · JAMA psychiatry · 2019PMID 30758486 ↗20Opioids for Chronic Noncancer Pain: A Systematic Review and Meta-analysisBusse JW, et al. · JAMA · 2018PMID 30561481 ↗21Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment-a Systematic ReviewSorensen CJ, et al. · Journal of medical toxicology : official journal of the American College of Medical Toxicology · 2017PMID 28000146 ↗22Cannabis withdrawal and sleep: A systematic review of human studiesGates P, et al. · Substance abuse · 2016PMID 25893849 ↗23Care and feeding of the endocannabinoid system: a systematic review of potential clinical interventions that upregulate the endocannabinoid systemMcPartland JM, et al. · PloS one · 2014PMID 24622769 ↗24The effects of cannabinoid administration on sleep: a systematic review of human studiesGates PJ, et al. · Sleep medicine reviews · 2014PMID 24726015 ↗25A Randomized Controlled Trial of the Safety and Efficacy of Dronabinol for Agitation in Alzheimer's DiseaseRosenberg PB, et al. · The American journal of geriatric psychiatry : official journal of the American Association for Geriatric Psychiatry · 2026PMID 41350162 ↗26Cannabinol for Acute Treatment of Insomnia Disorder in a Randomized Placebo-Controlled Crossover TrialLavender IG, et al. · Journal of sleep research · 2026PMID 41698831 ↗27Alleviation of Pain, PAIN Interference, and Oxidative Stress by a Novel Combination of Hemp Oil, Calamari Oil, and Broccoli: A Randomized, Double-Blind, Placebo-Controlled TrialCarlisle C, et al. · Nutrients · 2023PMID 37375558 ↗28Correlates of treatment engagement and client outcomes: results of a randomised controlled trial of nabiximols for the treatment of cannabis use disorderMills L, et al. · Substance abuse treatment, prevention, and policy · 2022PMID 36209081 ↗29A Phase 2 Randomized Controlled Trial of the Efficacy and Safety of Cannabidivarin as Add-on Therapy in Participants with Inadequately Controlled Focal SeizuresBrodie MJ, et al. · Cannabis and cannabinoid research · 2021PMID 33998885 ↗30Medical cannabis for chronic pain: a randomised controlled trialWare MA et al. · CMAJ · 2015PMID 25972454 ↗31Cannabinoids for medical use: a systematic review and meta-analysisWhiting PF et al. · JAMA · 2015PMID 26103030 ↗
Published research results
Reported results grouped by condition. Values and units are preserved as recorded; missing information is not estimated.
How to read this table
- Benefit
- What the trial saw happen: whether the measured outcome moved in the helpful direction in that one study (the tag on each row: “Benefit seen”, “No clear benefit”, “Possible harm” or “Unclear”). It is a study result — not advice, and not a promise it will work for you.
- Evidence
- Study design describes how research was conducted. It is not a formal certainty assessment.
- Effect size
- The result recorded in this summary. “Not reported” means the value is missing from the summary; it does not establish that the publication omitted it.
Reported direction, numerical results and study design are separate. Certainty has not been formally graded in this table.
Chronic Pain (4 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| dizziness | Synthetic high THC products probably increase dizziness risk versus placebo in 1740 people over 1 to 6 months.Possible harm | Not reported Recorded unit: Not reported | Sample (as reported): 1740 Follow-up: 1 to 6 months | Systematic review · 2022 Study detailsCannabis-Based Products for Chronic Pain : A Systematic Review. Systematic Review |
| pain severity and response | Synthetic high THC products may moderately improve pain severity and response versus placebo in 1740 people over 1 to 6 months.Benefit seen | Not reported Recorded unit: Not reported | Sample (as reported): 1740 Follow-up: 1 to 6 months | Systematic review · 2022 Study detailsCannabis-Based Products for Chronic Pain : A Systematic Review. Systematic Review |
| sedation | Synthetic high THC products increase sedation risk versus placebo in 1740 people over 1 to 6 months.Possible harm | Not reported Recorded unit: Not reported | Sample (as reported): 1740 Follow-up: 1 to 6 months | Systematic review · 2022 Study detailsCannabis-Based Products for Chronic Pain : A Systematic Review. Systematic Review |
| study withdrawal due to adverse events | Extracted high THC products increase withdrawal risk due to adverse events versus placebo in 1740 people over 1 to 6 months.Possible harm | Not reported Recorded unit: Not reported | Sample (as reported): 1740 Follow-up: 1 to 6 months | Systematic review · 2022 Study detailsCannabis-Based Products for Chronic Pain : A Systematic Review. Systematic Review |
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
What publications report
Outcome rows from the linked papers’ curated records. Educational, not medical advice. Ordered by strength of evidence, then result direction.
Figures are reported as published; designs and populations vary. We do not interpret results or give medical advice.
Outcomes & conditions
Outcomes & conditions →Why people look into Cannabis (THC) — and what they report
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
Availability
Where to get Cannabis (THC) (UK)
How this compound is sold in the UK, and where our readers typically find it.
Prescription-only in the UK
Cannabis (THC) can't legally be sold over the counter here. It's available only with a prescription, through a consultation with a doctor or qualified prescriber. We don't sell medicines and never will — our job is the evidence, not the dispensing.
How prescription-only compounds work →