Evidence-based cannabis information for adults 50 and older Peer-reviewed citations · Always talk to your doctor or pharmacist · No product sales

Questions to Ask Your Pharmacist About Cannabis

A printable list of the questions every senior should bring to a pharmacist consultation before starting or changing cannabis use.

Why This Conversation Matters

A 5-minute pharmacist consultation can prevent a hospitalization. Older adults take an average of five prescription medications, and both CBD and THC interact with the liver enzymes that metabolize many of them. Your pharmacist is trained to identify these interactions — your dispensary budtender is not.

Print this page, bring it to your next pharmacy visit, and work through these questions together. You do not need to feel embarrassed. Pharmacists increasingly encounter cannabis questions and are equipped to help.

Questions to Bring to Your Pharmacist

Bring a complete list of every medication you take — prescription, over-the-counter, and supplements — along with the cannabis products you are using or considering. Then ask:

Drug Interaction Questions

  • "Do any of my medications interact with CBD or THC through liver enzymes?"
    CBD inhibits CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP1A2. THC inhibits CYP2C9 and CYP3A4. Your pharmacist can cross-reference your medication list against these pathways.
  • "Should any of my medication doses be adjusted?"
    If cannabis raises blood levels of a medication, your prescribing physician may need to reduce the dose. This is especially important for warfarin, where INR increases from +0.4 to +9.61 have been documented.
  • "Are there safer medication alternatives I should discuss with my doctor?"
    Example: simvastatin is metabolized by CYP3A4 and interacts with CBD, while rosuvastatin bypasses CYP3A4 and is a safer alternative. Your pharmacist can identify switches like this.
  • "How much time should I leave between taking cannabis and my other medications?"
    Timing can reduce peak-level interactions for some medications. Your pharmacist can help you build a schedule.
  • "Am I on any medications with a narrow therapeutic index?"
    Drugs like warfarin, tacrolimus, and certain antiepileptics have very small margins between effective and toxic doses. Even modest CYP450 inhibition can push levels into dangerous territory.

Monitoring Questions

  • "Should I have any blood work done before starting cannabis?"
    Baseline liver function tests may be warranted, especially if you take valproate or other hepatotoxic medications. Warfarin users need INR monitoring at least weekly during the adjustment period.
  • "What side effects should I watch for that might indicate an interaction?"
    Unusual bruising (blood thinners), excessive drowsiness (benzodiazepines, opioids), muscle pain (statins), or mood changes (antidepressants) can signal that a medication level has shifted.

Product-Specific Questions

  • "Given my medications, should I use CBD, THC, or a combination?"
    CBD is actually a more potent enzyme inhibitor than THC. In some cases, a low-dose THC product may pose fewer interaction risks than a high-dose CBD product.
  • "Would a topical product avoid the interaction risks entirely?"
    Topical cannabinoid products produce negligible systemic absorption, meaning effectively no drug interactions. They may be appropriate for localized pain when systemic interactions are a concern.

Tools Your Pharmacist Can Use

If your pharmacist is unfamiliar with cannabinoid interactions, these resources can help:

  • CANN-DIR (cann-dir.psu.edu) — A free cannabinoid drug interaction screening tool developed by Kent Vrana, PhD, and Paul Kocis, PharmD, at Penn State College of Medicine. Available in 11 languages. Evidence-based and designed for clinical use.
  • Epidiolex FDA prescribing information — Contains the most rigorous cannabinoid interaction data available, drawn from controlled clinical trials.
  • Lexicomp and Micromedex — Standard drug interaction databases that increasingly include cannabinoid entries.

States Leading on Pharmacist Integration

Pennsylvania mandates pharmacist presence in all medical cannabis dispensaries — the gold standard for patient safety. Minnesota's LeafLine Labs model includes 30- to 45-minute initial pharmacist consultations with ongoing dosing relationships. These models demonstrate what cannabis care should look like for older adults, even if most states have not yet adopted them.

  • Drug Interactions — Detailed breakdown of cannabinoid interactions with warfarin, benzodiazepines, statins, opioids, and more
  • Dosing Journal — Track your cannabis use and share it with your pharmacist at each visit
  • Find a Cannabis-Friendly Doctor — Certification platforms and what to look for in a provider