Viread (tenofovir disoproxil fumarate, or TDF) is an antiviral medicine used to treat:

• HIV-1 infection (as part of combination antiretroviral therapy)
• Chronic hepatitis B virus (HBV) infection

TDF is a nucleotide reverse transcriptase inhibitor (NRTI). It works by blocking the reverse transcriptase enzyme that both HIV and hepatitis B virus use to copy their genetic material. Once in the body, TDF is converted to its active form (tenofovir), which competes with natural building blocks of DNA and stops viral replication.

Take one tablet once daily, with or without food. Take at the same time each day.

For HIV: Viread must always be used in combination with other antiretroviral medicines. Never take it as the sole HIV treatment.

Do not stop without speaking to your doctor. Stopping can lead to HIV rebound or, in hepatitis B, a potentially serious hepatitis B flare.

If you remember within 12 hours of your usual time, take it as soon as possible and continue your normal schedule. If more than 12 hours have passed, skip the missed dose and take the next one as usual. Never take a double dose.

Contact your doctor or a poison control centre.

• Store below 25°C in the original container
• Keep out of reach of children

Viread is generally well tolerated in the short to medium term, but longer-term effects on the kidneys and bones require monitoring.

Common side effects:

• Nausea, diarrhoea, vomiting
• Headache
• Dizziness
• Fatigue

Important long-term effects:

• Kidney problems: TDF can cause injury to kidney tubules, a condition called Fanconi syndrome in severe cases. Kidney function and urine protein should be monitored regularly
• Bone density reduction: TDF causes a reduction in bone mineral density over time, increasing the risk of fractures. This is less of a problem with the newer TAF formulation (found in Vemlidy)

Serious concerns:

• Lactic acidosis: a rare but serious metabolic complication. Report severe fatigue, abdominal pain, breathing difficulties, or nausea and vomiting that doesn't improve
• Hepatitis B flare on stopping: stopping Viread in a hepatitis B patient can trigger a severe, potentially fatal hepatitis flare

Regular monitoring of kidney function (creatinine, estimated GFR, urine protein) and bone density assessment are part of long-term care on Viread.

• Atazanavir: TDF slightly reduces atazanavir levels
• Didanosine: TDF increases didanosine exposure significantly. Avoid or use with close monitoring
• NSAIDs (ibuprofen, naproxen): increased risk of kidney damage

Tell your doctor about all medicines before making any changes.

Is Viread (TDF) or Vemlidy (TAF) better for my kidneys?

Vemlidy (TAF) is generally preferred over Viread (TDF) for patients with existing kidney problems or reduced bone density, because TAF delivers active tenofovir to cells at a much lower plasma concentration, resulting in significantly less kidney tubule and bone toxicity. For people with healthy kidneys and no bone concerns, TDF remains a safe and widely used option. Your doctor will choose based on your individual kidney function, bone health, and other factors.

Can Viread treat both HIV and hepatitis B?

Yes. TDF has antiviral activity against both HIV and hepatitis B virus. If you have both infections (HIV-HBV co-infection), Viread (as part of a full antiretroviral regimen) can treat both simultaneously. This is actually clinically important: if you have hepatitis B and start or stop HIV treatment, this must be planned carefully to avoid triggering a hepatitis B flare.

Ace provides accurate and independent information medically reviewed on prescription medications. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.