Drug Interaction Report

Lenacapavir and Avanafil: Interaction Details

A pharmacist-reviewed analysis of the Lenacapavir and Avanafil interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Lenacapavir

Sunlenca Yeztugo
+

Avanafil

Stendra Stendra®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 75 documented Lenacapavir interactions, 72 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

Increased sensitive CYP3A substrate exposure

Interaction Deep Dive

Coadministration of lenacapavir (SUNLENCA®)(a moderate CYP3A inhibitor) together with a PDE-5 inhibitor/sensitive CYP3A substrate may increase PDE-5 inhibitor/sensitive CYP3A substrate exposure1. Lenacapavir may increase the exposure of drugs primarily metabolized by CYP3A, initiated within 9 months after the last dose of lenacapavir, which may also increase the potential risk of adverse reactions 12.

Why it happens (mechanism)

Inhibition of CYP3A-mediated metabolism of sensitive CYP3A substrates

Common questions

Can I take Lenacapavir and Avanafil together?

Increased sensitive CYP3A substrate exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Lenacapavir and Avanafil 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.

Questions for your pharmacist

  • Does my dose of Lenacapavir or Avanafil 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)

  1. Product Information: SUNLENCA(R) oral tablets, subcutaneous injection, lenacapavir oral tablets, subcutaneous injection. Gilead Sciences Inc (per FDA), Foster City, CA, 2024. DailyMed
  2. Product Information: YEZTUGO(R) oral tablets, subcutaneous injection, lenacapavir oral tablets, subcutaneous injection. Gilead Sciences Inc (per manufacturer), Foster City, CA, 2025. DailyMed
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Lenacapavir

Keep reading about Lenacapavir

All Lenacapavir interactions (75)
Also serious with: Encorafenib Colchicine Nisoldipine Letermovir Injection
Avanafil

Keep reading about Avanafil

All Avanafil interactions (113) Avanafil drug information
Also serious with: Nitroglycerin Transdermal Patch Isosorbide Amyl Nitrite Erythrityl Tetranitrate
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Lenacapavir + Activated Charcoal Grapefruit St. John's Wort Acacia Rigidula Adrafinil African Wild Potato American Elder Astaxanthin + 130 more
Avanafil + Activated Charcoal American Mistletoe Grapefruit Hawthorn St. John's Wort Acacia Rigidula Adrafinil African Wild Potato + 136 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.