Tenofovir is a cornerstone of antiretroviral therapy (ART) for managing Human Immunodeficiency Virus (HIV) and is also a primary treatment for chronic Hepatitis B Virus (HBV) infection [1.7.4, 1.7.7]. It works by inhibiting reverse transcriptase, an enzyme crucial for viral replication [1.7.4]. The medication comes in two main forms: tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) [1.6.1]. While both are effective, they have different safety profiles, particularly concerning the kidneys and bones [1.6.2]. TAF is a newer prodrug designed to deliver the active agent more efficiently to target cells, resulting in 90% lower plasma concentrations of tenofovir compared to TDF [1.6.2, 1.6.5]. This reduction is associated with improved renal and bone safety markers [1.6.2, 1.6.6]. Understanding what to avoid while on this medication is essential for maximizing its benefits and preventing serious adverse effects.
Key Medications to Avoid or Use with Caution
Since tenofovir is eliminated from the body through the kidneys, its most significant interactions involve other drugs that affect renal function [1.5.2, 1.5.4]. Combining tenofovir with these medications can increase drug concentrations in the blood and elevate the risk of kidney damage (nephrotoxicity) [1.3.1, 1.4.2].
Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
One of the most critical interactions to be aware of is with NSAIDs. Commonly used over-the-counter pain relievers like ibuprofen (Advil, Motrin) and naproxen (Aleve) fall into this category [1.3.3, 1.4.1]. Concurrent or recent use of high-dose or multiple NSAIDs with tenofovir, particularly the TDF formulation, should be avoided [1.4.3, 1.4.6]. The combination significantly increases the risk of kidney problems, including acute kidney injury [1.4.2, 1.4.3]. If you regularly require pain medication, discuss safer alternatives with your healthcare provider.
Other Nephrotoxic Drugs
Beyond NSAIDs, several other prescription medications are known to be potentially harmful to the kidneys (nephrotoxic) and should be used with extreme caution. These drugs can interfere with the way tenofovir is cleared from the body, leading to toxic accumulation [1.3.1]. Examples include:
- Certain antibiotics, such as aminoglycosides (e.g., amikacin, gentamicin) [1.3.3]
- Antiviral drugs like adefovir (Hepsera) and cidofovir [1.5.2, 1.7.7]
- Other medications that compete for active tubular secretion in the kidneys [1.3.1, 1.5.4]
Drugs Affecting Tenofovir Concentration
Certain medications, such as some anticonvulsants (phenytoin, carbamazepine, phenobarbital) and the herbal supplement St. John's wort, can decrease the concentration of tenofovir alafenamide (TAF) in the blood [1.3.1]. This can reduce the antiviral efficacy of the medication, potentially leading to treatment failure or the development of drug resistance [1.3.1, 1.7.4]. Co-administration with these drugs is not recommended [1.3.1].
Comparison Table: TDF vs. TAF Safety Profiles
| Feature | Tenofovir Disoproxil Fumarate (TDF) | Tenofovir Alafenamide (TAF) |
|---|---|---|
| Plasma Concentration | Higher systemic exposure to tenofovir [1.6.2] | Approximately 90% lower plasma tenofovir levels [1.6.5] |
| Kidney Safety | Associated with a greater risk of kidney function decline and tubular dysfunction [1.5.4, 1.6.2]. Monitoring of kidney function is crucial [1.5.4]. | Significantly smaller increases in serum creatinine and less proteinuria. Considered to have a better renal safety profile [1.6.1, 1.6.2]. |
| Bone Health | Associated with greater decreases in bone mineral density (BMD) at the hip and spine [1.6.2, 1.6.6]. | Significantly smaller impact on BMD, showing less bone loss [1.6.2, 1.6.5]. |
| Common Combinations | Viread, Truvada, Atripla, Stribild [1.2.3, 1.7.7] | Vemlidy, Descovy, Biktarvy, Genvoya, Odefsey [1.7.1, 1.7.7] |
| Food Interaction | Can be taken with or without food, though a high-fat meal can increase absorption by about 40% [1.2.1, 1.2.3]. | Should be taken with food [1.2.6]. |
Lifestyle and Other Considerations
Pre-existing Health Conditions
Patients with pre-existing kidney disease are at a higher risk for tenofovir-associated nephrotoxicity [1.5.2, 1.5.4]. For these individuals, dose adjustments or the use of the safer TAF formulation may be necessary [1.5.4]. Similarly, individuals with low bone mineral density or a history of fractures should discuss the risks with their doctor, as tenofovir (especially TDF) can contribute to bone loss [1.6.2, 1.7.2].
Alcohol Consumption
While there are no known direct interactions between tenofovir and alcohol, excessive alcohol use can contribute to liver damage [1.7.7]. Since tenofovir is used to treat Hepatitis B, a liver disease, it is generally wise to limit alcohol intake to protect your liver health [1.7.7].
Staying Hydrated
Maintaining adequate hydration is important for kidney health in general and may be particularly beneficial for those taking medications that are cleared by the kidneys. Dehydration can be a risk factor for acute renal failure in patients taking tenofovir [1.4.5].
Conclusion
To safely and effectively use tenofovir, open communication with your healthcare provider is paramount. Always disclose all prescription drugs, over-the-counter medications, and supplements you are taking [1.2.2]. The most significant risk comes from combining tenofovir with drugs that also affect the kidneys, especially NSAIDs [1.4.3, 1.7.7]. Regular monitoring of kidney and bone health is a standard part of care for patients on tenofovir [1.7.2, 1.7.4]. By avoiding interacting substances and adhering to medical advice, patients can minimize risks and achieve the best possible outcomes from their treatment.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before making any decisions about your treatment. For more detailed drug information, you can visit MedlinePlus [1.4.1].
