Hello there! In our latest post, we will be discussing a crucial topic: Tenofovir interactions. If you're taking this medication, it's essential to understand how it can interact with other substances, from prescription drugs to over-the-counter supplements. We'll explore potential side effects and cautionary advice, to help you stay safe and informed. Remember, when it comes to medication, knowledge is power!
Tenofovir interactions: what to watch for
Tenofovir (TDF or TAF) is a backbone drug for HIV and HBV treatment. It’s usually well tolerated, but interactions can raise the risk of kidney or bone problems or reduce treatment effectiveness. Here’s a simple, practical guide to the most important interactions and what you should do about them.
Main drug interactions
Nephrotoxic medicines: Drugs that can harm the kidneys make tenofovir’s side effects worse. Watch for NSAIDs (ibuprofen, naproxen), aminoglycoside antibiotics (gentamicin), amphotericin B, cidofovir and adefovir. If you need one of these, your doctor should check kidney function more often.
Boosted protease inhibitors and boosters: Ritonavir or cobicistat used with certain protease inhibitors (for example, boosted atazanavir or darunavir) can raise tenofovir levels. Higher tenofovir exposure increases the chance of kidney or bone toxicity, so clinicians often avoid TDF with these combinations or switch to TAF or another regimen.
Didanosine (ddI): Tenofovir and didanosine together can cause serious side effects like pancreatitis and high didanosine levels. This combo is generally not recommended.
Drugs affecting renal clearance: Any medicine that changes how the kidneys handle drugs can alter tenofovir levels. Trimethoprim-sulfamethoxazole can raise creatinine without changing true kidney filtering, but it still needs attention. Your prescriber will know which pairs need closer monitoring or dose changes.
Herbs and enzyme inducers: Tenofovir itself is not heavily processed by liver enzymes, so classic enzyme inducers like St. John’s wort don’t lower tenofovir directly. But if you’re on a combo HIV regimen, herbal inducers can reduce levels of other medicines in your regimen and risk treatment failure. Always list supplements to your provider.
Food, monitoring, and practical tips
Food: TDF absorption is not strongly affected by food. TAF is better absorbed with food, especially a higher-fat meal, so follow your prescriber’s instructions for TAF dosing.
Baseline checks: Before starting tenofovir, get creatinine/eGFR, serum phosphate and hepatitis tests. If you have risk factors (older age, diabetes, existing kidney disease), discuss bone density testing too.
Ongoing monitoring: Routine kidney tests (creatinine, eGFR) are common in the first months and periodically after. Check phosphate if you have symptoms like bone pain or muscle weakness. If creatinine rises or urine output falls, contact your clinician right away.
Tell your provider about everything you take: OTC drugs, antibiotics, supplements, and herbal remedies. That simple step prevents many problems. If you need an NSAID often for pain, ask about safer pain options while on tenofovir.
Final practical note: if your clinician flags a risky drug combination, they’ll usually switch the antiretroviral or the interacting medicine. Don’t stop tenofovir or change doses on your own—always follow medical advice.
