What are the guidelines for using cannabis (cannabinoids) for medical purposes?

Medical Cannabis Guidelines: Evidence-Based Recommendations

Primary Recommendation

Cannabis and cannabinoids should NOT be used as cancer-directed treatment outside of clinical trials, and evidence supports only limited medical indications: specifically, refractory chemotherapy-induced nausea/vomiting when added to standard antiemetics. 1

Established Medical Uses

Refractory Chemotherapy-Induced Nausea and Vomiting (CINV)

• Synthetic cannabinoids (dronabinol, nabilone) may be used as salvage antiemetics when standard guideline-concordant regimens fail for moderate to highly emetogenic chemotherapy 1
• Dosing for dronabinol: Start 2.5 mg orally three times daily, up-titrate to maximum 10 mg three to four times daily 1
• Dosing for nabilone: Start 1 mg orally twice daily, up-titrate to maximum 2 mg four times daily 1
• No renal or hepatic dose adjustments required 1

Other Potential Medical Applications

• Pain management: Small to modest benefits in chronic pain, though evidence quality is low 2, 3
• Muscle spasticity: Particularly in multiple sclerosis, with modest benefits 2, 3
• Refractory epilepsy: CBD specifically shows benefit 2, 3
• Appetite stimulation: Limited supporting data 3

What NOT to Use Cannabis For

Do not recommend cannabis/cannabinoids for:

• Cancer treatment itself (no antineoplastic effect demonstrated) 1
• High-dose CBD (≥300 mg/day) for symptom management due to lack of efficacy and risk of reversible liver enzyme abnormalities 1
• Most other cancer-related symptoms outside clinical trials - evidence is insufficient 1
• Quality of life improvement - no significant benefit demonstrated 1

Clinical Communication Framework

Routine Assessment Required

Clinicians must routinely and nonjudgmentally inquire about cannabis use given 20-40% of cancer patients report use 1

Essential history elements to document: 1

• Current and prior cannabis use patterns
• Product types and THC:CBD ratios
• Route of administration (inhaled, oral, transdermal)
• Source (medical dispensary vs. informal)
• Perceived effectiveness and side effects
• Goals of use

Language Matters

• Avoid stigmatizing terms like "user" or "addict" 1
• Use patient's preferred terminology 1
• Remain sensitive to disproportionate legal impacts on marginalized communities 1

Pharmacokinetics: Critical Dosing Considerations

Route-Dependent Absorption

• Oral THC: 4-12% bioavailability, onset 30 minutes to 2 hours, duration 5-8 hours 1
• Inhaled THC: 10-35% bioavailability, onset seconds to minutes, duration 2-3 hours 1
• High-fat meals significantly increase oral absorption - warn patients about enhanced effects 1

Start Low, Go Slow Approach

Critical dosing principle: Begin at lowest possible dose and titrate slowly to avoid adverse effects 1

• Patients unfamiliar with oral products must wait ≥1 hour before additional dosing 1
• Stacking doses (taking more before onset) commonly causes adverse effects 1

Safety Considerations and Adverse Effects

Common Adverse Effects

Expect these dose-limiting side effects: 1

• Euphoria and drowsiness
• Dizziness and vertigo
• Hallucinations and mood changes
• Sedation (19% in clinical trials)
• Disorientation (3%)

Serious Safety Concerns

Driving and safety-sensitive work: 1

• Avoid driving for up to 12 hours after cannabis consumption
• Risk of motor vehicle accidents more than doubles 1
• Applies to operating heavy equipment and working with vulnerable populations

Drug interactions: 1

• Warfarin, buprenorphine, tacrolimus require monitoring
• Concurrent opioid use increases pharmacodynamic interaction risk
• May exacerbate psychotic disorders

Contraindications and cautions: 1

• History of substance use disorder predisposes to cannabis use disorder
• Adolescents and young adults at higher risk for adverse outcomes 2
• Pregnancy concerns: prematurity and restricted fetal growth 2

Storage Safety

Prevent accidental exposure: 1

• Store in locked location, out of reach of children and pets
• Keep separate from regular food/drinks
• Use child-resistant packaging
• Edibles (baked goods, candies) pose highest accidental ingestion risk

Product Quality and Sourcing

Favor formally sourced products from medical dispensaries over informal sources 1

• Dispensary products undergo testing for cannabinoid concentrations
• Screened for heavy metals and contaminants
• Labeled with THC:CBD ratios

Evidence Quality Assessment

The evidence base is weak: 1

• Most outcomes have low or very low certainty evidence
• Limited high-quality RCTs available
• Most research focuses on THC; minimal CBD data
• Results show varying and conflicting effects

Critical research gap: Cannabis access has outpaced supporting science 1

When to Refer

Refer to medical cannabis specialist if: 1

• Clinician lacks knowledge/training in medical cannabis
• Uncomfortable discussing the topic
• Complex patient requiring specialized guidance
• Maintain ongoing communication with specialists to ensure safe use

Legal Context

Federal vs. state law conflict: 1

• Cannabis remains Schedule I federally (no accepted medical use)
• 38 states have legalized medical cannabis
• Discuss local regulations with patients to avoid legal consequences 1