Vemlidy Drug Interactions: What to Avoid and What to Tell Your Doctor

Vemlidy (tenofovir alafenamide, or TAF) can interact with a number of common medications, supplements, and herbal products. Some interactions can make Vemlidy less effective at controlling hepatitis B; others can increase the risk of side effects like kidney damage. This guide covers the most important interactions and what you need to tell your healthcare team.

Why Does Vemlidy Have Drug Interactions?

Vemlidy is a substrate of two important drug transporters in the body: P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). These proteins control how much drug enters cells and how much gets pumped out. Medications that affect P-gp or BCRP activity can change how much Vemlidy your body absorbs and processes.

P-gp/BCRP inducers (drugs that speed up these transporters) — decrease Vemlidy absorption, meaning less drug reaches the liver → Vemlidy becomes less effective

P-gp/BCRP inhibitors (drugs that slow these transporters) — increase Vemlidy exposure, which may amplify side effects

Medications to AVOID with Vemlidy (Major Interactions)

These combinations are not recommended by the prescribing information because they can significantly reduce Vemlidy's effectiveness:

Rifampin (Rifadin) — a TB antibiotic that is a powerful P-gp/BCRP inducer; can substantially lower TAF levels and cause treatment failure

Rifabutin and Rifapentine — related antibiotics used for TB and MAC infections; also P-gp/BCRP inducers; avoid with Vemlidy

Phenobarbital — anticonvulsant (seizure medication); potent P-gp inducer that can significantly reduce TAF absorption

Phenytoin (Dilantin) — another seizure medication; P-gp inducer; reduces Vemlidy levels

Oxcarbazepine (Trileptal) — seizure and mood stabilizer; P-gp/BCRP inducer; reduces TAF levels

St. John's Wort — herbal supplement for mood; a well-known P-gp inducer that can significantly lower Vemlidy levels; do NOT use with Vemlidy

What to do: If you're taking any of the above medications, talk to your provider before starting Vemlidy. Alternative anticonvulsants or TB regimens that don't affect P-gp may be available.

Do Not Take Vemlidy With Other Tenofovir-Containing Medications

You should NOT take Vemlidy at the same time as any other medication that contains tenofovir. This includes:

Viread (tenofovir disoproxil fumarate/TDF)

Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide)

Descovy (emtricitabine/tenofovir alafenamide)

Genvoya (elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide)

Truvada (emtricitabine/tenofovir disoproxil fumarate)

Atripla, Stribild, Complera, Odefsey, and other TDF/TAF-containing combination pills

Combining Vemlidy with any of these creates duplicate tenofovir exposure that can harm kidneys and bones.

Use Caution With These Medications (Moderate Interactions)

Cyclosporine — a P-gp/BCRP inhibitor used in transplant patients; may increase TAF levels. Monitor closely if coadministered.

NSAIDs (ibuprofen, naproxen, aspirin at high doses) — can increase the risk of kidney toxicity when combined with tenofovir products. Occasional low-dose use may be acceptable, but regular use should be discussed with your doctor. Acetaminophen (Tylenol) is generally a safer alternative.

Tafamidis — a BCRP inhibitor for transthyretin amyloidosis; may increase TAF exposure. Dosage adjustment may be needed — consult your prescriber.

Tepotinib — a cancer medication that inhibits P-gp; may increase TAF levels. Avoid if possible, or adjust dose per label.

Supplements and Herbal Products to Discuss With Your Doctor

Many patients don't think of supplements and herbal products as real medications — but they can have significant interactions with prescription drugs. When taking Vemlidy, discuss any supplements with your doctor, especially:

St. John's Wort — strongly contraindicated (major interaction)

Herbal remedies for liver health — some traditional Chinese or Southeast Asian liver supplements may contain compounds that interact with P-gp transporters

High-dose vitamin D or calcium supplements — generally safe but inform your provider, especially given bone monitoring while on Vemlidy

What to Tell Your Doctor and Pharmacist Before Starting Vemlidy

Before starting Vemlidy, give your provider and pharmacist a complete list of:

All prescription medications (including HIV antivirals if applicable)

Over-the-counter medications (especially NSAIDs and antacids)

All vitamins and supplements

Herbal remedies and traditional medicines

For a complete overview of Vemlidy's side effects and safety, see: Vemlidy Side Effects: What to Expect and When to Call Your Doctor.