Hepatitis B Antivirals (Tenofovir, Entecavir)
Daily tablets that suppress hepatitis B virus and prevent liver damage. Highly effective and well-tolerated. Usually taken long-term — sometimes for life.
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
Drug class
Nucleos(t)ide reverse transcriptase inhibitors for hepatitis B
Examples
Tenofovir disoproxil fumarate (TDF, Viread), tenofovir alafenamide (TAF, Vemlidy) — newer with fewer kidney/bone effects, entecavir (Baraclude). Older drugs (lamivudine, adefovir, telbivudine) are less used due to resistance.
How it works
These drugs block reverse transcriptase, an enzyme that hepatitis B virus needs to copy itself. With consistent use, the virus is suppressed to undetectable levels. Liver damage stops; in many patients fibrosis even reverses. The drugs do not eliminate the virus from the body — that's why most patients need lifelong treatment.
What it treats
- Chronic hepatitis B in patients meeting treatment criteria
- Prevention of mother-to-child transmission (high-viral-load mothers from week 28)
- Prophylaxis before chemotherapy or biologics in HBsAg-positive patients (prevents reactivation)
- Some patients with HBV cirrhosis (decompensated)
How to take it
Tenofovir disoproxil (TDF): 300 mg once daily, with or without food.
Tenofovir alafenamide (TAF): 25 mg once daily, with food.
Entecavir: 0.5 mg once daily on an EMPTY stomach (1 mg if prior lamivudine resistance).
Take at the same time every day. Don't miss doses — interruptions can cause flares.
Common side effects
- Generally well tolerated — most patients have no side effects
- TDF: occasional nausea, fatigue, headache; rare bone or kidney issues with long-term use
- TAF: similar but with much less kidney and bone impact
- Entecavir: occasional nausea, fatigue
Serious side effects — call your doctor
Severe muscle pain or weakness, dark urine
Possible lactic acidosis or rhabdomyolysis — emergency.
New jaundice or worsening liver function
Rare hepatotoxicity or HBV flare from poor adherence — see your doctor.
Persistent kidney function decline (TDF)
Switch to TAF or alternative.
Bone pain (TDF long-term)
Bone density check, consider switching to TAF.
Interactions
TDF: avoid combining with other nephrotoxic drugs (NSAIDs, aminoglycosides) when possible. Entecavir: few interactions but adjust dose for kidney function. TAF: minimal interactions.
Monitoring
Every 3-6 months: HBV DNA, ALT, kidney function (creatinine, eGFR, urine protein for TDF), CBC. Every 6 months: HBeAg/Anti-HBe in eAg-positive patients. Every 6 months: ultrasound + AFP for liver cancer surveillance if cirrhosis or other HCC risk factors.
When and how to stop
Most patients need LIFELONG treatment. Stopping causes the virus to come back, often with a flare. In carefully selected patients (HBeAg seroconversion + sustained suppression for years + no cirrhosis), discontinuation can be tried but with close monitoring. NEVER stop without your doctor.
Pregnancy & breastfeeding
Tenofovir (TDF) is the preferred drug in pregnancy — large safety data. Pregnant women with HBV DNA >200,000 IU/mL should receive tenofovir from week 28 to delivery to prevent transmission to baby. Combined with newborn vaccination + HBIG, transmission risk drops to <1%. Continue treatment in mothers who need it.
In the Saudi context
All hepatitis B antivirals are MOH-approved and widely available. Insurance plans cover treatment. The Saudi MOH provides free hepatitis B testing and treatment, including for pregnant women.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Should I be on TDF or TAF?
- When can I stop my hepatitis B medication?
- How often do I need ultrasound and AFP?
Medically reviewed by: SGA Patient Education Panel · Last reviewed 24/04/2026