Cannabidiol and Letermovir Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cannabidiol
Letermovir Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced active cannabidiol metabolite exposure and an altered cannabidiol exposure
Interaction Deep Dive
Concomitant use of cannabidiol (CYP2C19 substrate) with letermovir (CYP2C19 inducer) has resulted in reduced cannabidiol exposure as well as reduced exposure of 7-OH-CBD (active cannabidiol metabolite). Consider up to a 2-fold increase in cannabidiol dosage based on clinical response and tolerability when cannabidiol is coadministered with letermovir2. Additionally, concomitant use of letermovir and cannabidiol (CYP3A substrate) may result in increased cannabidiol exposure 1.
Why it happens (mechanism)
Induction of CYP2C19-mediated metabolism of cannabidiol; inhibition of CYP3A-mediated metabolism of cannabidiol
Literature reports
2 reports — tap to read
a) In a drug interaction study, coadministration of letermovir (oral 240 mg once daily) with a CYP3A substrate, midazolam (1 mg single dose IV) led to increased AUC, Cmax and C24hr of midazolam by 47%, 5% and 174%, respectively. And, coadministration of letermovir (oral 240 mg once daily) with midazolam (2 mg single dose orally) led to increased AUC and Cmax of midazolam by 125% and 72%, respectively 1.
b) In a drug interaction study, coadministration of cannabidiol and rifAMPin 600 mg once daily (CYP2C19 inducer) decreased cannabidiol concentrations by approximately 32%. There were moderate changes in exposure to the active metabolite 7-OH-CBD, which decreased by 63% for AUC and by 67% for Cmax. Metabolite 7-COOH-CBD also decreased by 48% for AUC, with no change in Cmax. The effects on the efficacy of cannabidiol are not known 2.
Common questions
Can I take Cannabidiol and Letermovir Injection together?
Reduced active cannabidiol metabolite exposure and an altered cannabidiol exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cannabidiol and Letermovir Injection interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Cannabidiol or Letermovir Injection need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: PREVYMIS(R) oral tablets, oral pellets, intravenous injection, letermovir oral tablets, oral pellets, intravenous injection. Merck Sharp & Dohme Corp (per FDA), Rahway, NJ, 2024. DailyMed
- Product Information: EPIDIOLEX(R) oral solution, cannabidiol oral solution. Jazz Pharmaceuticals, Inc. (per FDA), Palo Alto, CA, 2025. DailyMed
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