Tenofovir Alafenamide Drug Interactions: What You Need to Know

If you take Tenofovir Alafenamide (brand name Vemlidy), it's important to know which other medications, supplements, and substances can interact with it. Drug interactions can make your hepatitis B treatment less effective — or increase your risk of side effects.

This guide covers the major and moderate interactions to watch for, plus what to tell your doctor before starting treatment.

How Drug Interactions Work with Tenofovir Alafenamide

Tenofovir Alafenamide is transported into cells by a protein called P-glycoprotein (P-gp). Medications that affect P-gp can change how much Tenofovir Alafenamide gets into your cells — and that directly affects how well the drug works.

There are two main types of interactions to watch for:

• P-gp inducers — These speed up the removal of Tenofovir Alafenamide from your body, which can lower drug levels and make treatment less effective.
• Nephrotoxic drugs — Medications that stress the kidneys can increase the risk of kidney problems when combined with Tenofovir Alafenamide.

Medications That Interact with Tenofovir Alafenamide

Major Interactions — Avoid These

The following medications are P-gp inducers that can significantly reduce Tenofovir Alafenamide levels in your body. Using them together may cause your hepatitis B treatment to fail:

• Rifampin (Rifadin) — An antibiotic used to treat tuberculosis and certain other infections. This is one of the strongest P-gp inducers and should not be used with Vemlidy.
• Rifabutin (Mycobutin) — Another anti-tuberculosis medication that can lower TAF levels.
• Carbamazepine (Tegretol) — An anticonvulsant used for epilepsy and bipolar disorder.
• Phenobarbital — A barbiturate used for seizures.
• Phenytoin (Dilantin) — Another anticonvulsant for seizures.
• Oxcarbazepine (Trileptal) — An anticonvulsant related to Carbamazepine.

If you take any of these medications, your doctor will need to consider alternative hepatitis B treatments or alternative medications for your other condition.

Moderate Interactions — Use with Caution

These medications may increase the risk of kidney problems when taken with Tenofovir Alafenamide:

• Aminoglycoside antibiotics (Gentamicin, Tobramycin, Amikacin) — These can be toxic to the kidneys. Combining them with Tenofovir Alafenamide increases nephrotoxicity risk.
• High-dose or multiple NSAIDs (Ibuprofen/Advil, Naproxen/Aleve, Diclofenac) — Occasional use of an NSAID at normal doses is generally fine, but regular high-dose use can stress the kidneys. Talk to your doctor if you rely on NSAIDs for pain management.
• Other nephrotoxic agents — Any medication known to affect kidney function should be discussed with your doctor. This includes certain chemotherapy drugs, Amphotericin B, and Vancomycin.

Supplements and OTC Products to Watch

St. John's Wort

This is the most important supplement interaction to know about. St. John's Wort is a strong P-gp inducer that can significantly reduce Tenofovir Alafenamide levels in your body. Do not take St. John's Wort while on Vemlidy. If you use it for mood support, ask your doctor about safer alternatives.

Other Supplements

While there are no other well-documented major supplement interactions with Tenofovir Alafenamide, always tell your doctor about any supplements you take, including:

• Herbal remedies and traditional medicines
• Vitamin and mineral supplements (especially high-dose calcium or iron, which can affect absorption of some medications)
• Probiotics or digestive enzymes

Over-the-Counter Pain Relievers

As mentioned above, NSAIDs like Ibuprofen (Advil, Motrin) and Naproxen (Aleve) are generally safe for occasional use but should be used with caution if you take them frequently. Acetaminophen (Tylenol) is usually a safer choice for routine pain relief when you're on Tenofovir Alafenamide, though you should still follow dosing guidelines — especially since hepatitis B already puts extra strain on your liver.

Food and Drink Interactions

Tenofovir Alafenamide has one important food interaction:

• Take it with food. Vemlidy should always be taken with a meal or snack. Food increases the absorption of the medication, making it more effective. Taking it on an empty stomach may reduce how much of the drug gets into your system.

There are no specific foods you need to avoid while taking Tenofovir Alafenamide. However, maintaining a healthy diet is important for liver health, especially if you have chronic hepatitis B. Limiting alcohol is generally recommended for anyone with liver disease — talk to your doctor about what's appropriate for you.

What to Tell Your Doctor

Before starting Tenofovir Alafenamide, make sure your doctor has a complete picture of everything you take. Here's a checklist:

• All prescription medications — especially anticonvulsants, antibiotics (particularly Rifampin-type drugs), and any medication for HIV
• Over-the-counter drugs — pain relievers, antacids, cold medications
• Supplements and herbal products — especially St. John's Wort
• Your kidney health history — let your doctor know about any past kidney problems
• HIV status — Vemlidy alone should not be used in patients co-infected with HIV-1. Your doctor should test you for HIV before prescribing.

If you're ever prescribed a new medication while taking Vemlidy, remind the prescribing doctor that you're on Tenofovir Alafenamide so they can check for interactions.

Final Thoughts

Tenofovir Alafenamide has relatively few drug interactions compared to many other medications, but the ones it does have are important. Avoiding strong P-gp inducers like Rifampin, Carbamazepine, and St. John's Wort is essential for keeping your treatment effective. And being cautious with nephrotoxic drugs helps protect your kidneys.

When in doubt, ask your doctor or pharmacist before starting any new medication or supplement. For more about Tenofovir Alafenamide, including side effects and dosage information, explore our other guides. And if you need help finding the medication in stock, Medfinder can help.