Research on the smoking route of administration for medical cannabis has been conducted across various conditions, with some conditions studied more extensively due to the rapid symptom relief smoking provides. Here is the ranking from most to least studied:

1. Chronic Pain
   Smoking cannabis is widely studied and commonly used for chronic pain management, as inhalation offers fast relief. Cannabis is shown to reduce neuropathic pain, arthritis pain, and cancer-related pain. Despite its effectiveness, long-term respiratory risks associated with smoking remain a concern​
   BMJ
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   AAFP
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2. Nausea and Vomiting
   Particularly for chemotherapy-induced nausea, smoking cannabis has been studied as a rapid-onset antiemetic. The inhalation route is effective in managing acute nausea episodes, but alternative methods like vaporization are now often preferred due to respiratory health concerns​
   Homepage
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   AHA Journals
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3. Multiple Sclerosis (MS)
   Inhaled cannabis has been explored for MS symptoms such as spasticity, pain, and muscle tightness, with positive results. Smoking offers a rapid delivery, though it has limitations due to inconsistent dosing and potential lung effects; alternative routes like oral sprays are often favored clinically​
   AAFP
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4. PTSD and Anxiety
   Smoking cannabis for PTSD and anxiety relief is reported in patient communities, though research data are limited. THC-rich strains may provide short-term relief for anxiety and intrusive thoughts, but inconsistent effects and risk of exacerbating anxiety in some users reduce its clinical preference​
   BMJ
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   AAFP
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5. Appetite Stimulation
   Smoking cannabis has shown benefits in appetite stimulation, especially for HIV/AIDS patients and those experiencing cachexia from cancer. Rapid onset makes it appealing for patients needing immediate effects, though alternative routes are preferred in clinical settings to reduce respiratory impact​
   Homepage
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   AHA Journals
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6. Epilepsy
   Inhaled cannabis is less commonly studied for epilepsy due to the variability in dosing and lack of consistency required for seizure control. Oral and sublingual routes with CBD-based medications like Epidiolex are the standard due to precise dosing and reduced psychoactive risk​
   JNNP
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   Epilepsy.com
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7. Glaucoma
   Earlier research investigated smoking cannabis for intraocular pressure reduction in glaucoma patients. However, the effect was short-lived, requiring frequent dosing that made smoking impractical for ongoing management. This route has since been largely abandoned for glaucoma​
   AAFP BM

To document medical necessity and patient preference for smoking cannabis for epilepsy, a structured approach includes both medical rationale and patient-specific factors. Here’s how to comprehensively document this in a clinical setting:

1. Medical History and Prior Treatment Documentation: Begin with a clear history of the patient’s epilepsy, noting the type of epilepsy, seizure frequency, and severity. Document previous and current treatments, including antiepileptic drugs, alternative therapies, and any other cannabinoid treatments that were ineffective, as well as any adverse reactions. Clearly stating that other therapies were inadequate or poorly tolerated helps substantiate the necessity for an alternative approach, such as smoking cannabis.

2. Specific Medical Necessity Justification: Highlight why rapid-onset seizure control is essential for this patient, especially if they experience acute, unpredictable seizures where immediate relief is critical. Reference studies supporting the efficacy of inhaled THC/CBD in seizure control, even if other forms are generally preferred for epilepsy. A statement might include, “Given the need for immediate bioavailability due to acute seizure events, the smoking route offers a rapid THC and CBD absorption that alternative routes (oral or sublingual) cannot achieve as promptly.” Cite peer-reviewed literature indicating the benefits of fast cannabinoid delivery for seizure mitigation (e.g., NYU Langone, 2023; Epilepsy Foundation, 2020) to strengthen the medical rationale.

3. Patient Preference and Shared Decision-Making: Document the patient’s informed preference after discussing alternative routes, risks, and benefits. Record details of the discussion around risks associated with smoking (e.g., respiratory effects) and the patient’s understanding and willingness to proceed. For instance, note, “Patient expressed an informed preference for smoking cannabis after discussing rapid seizure control needs and alternatives. Patient is aware of the respiratory risks but prioritizes seizure control due to the severe impact of acute seizure episodes on daily life.”

4. Informed Consent and Monitoring Plan: Obtain informed consent that reflects the patient’s understanding of both benefits and risks. Include a plan for follow-up and monitoring to assess effectiveness, potential side effects, and to reconsider alternative formulations if clinically appropriate. Document that follow-up visits will evaluate efficacy, dosing, and potential tolerance issues, underscoring the dynamic nature of treatment assessment.

5. Provider Notes on Clinical Judgment: Include a provider statement justifying why smoking was chosen as the immediate route. This might look like: “Considering the patient’s urgent need for rapid-onset seizure control, the immediate bioavailability provided by smoking cannabis outweighs the respiratory risks in this context of refractory epilepsy. Alternative, slower-acting methods have been ineffective.”