Patient Education1 min read

Hepatitis B Antivirals (Tenofovir, Entecavir)

Overview

Daily tablets that suppress hepatitis B virus and prevent liver damage. Highly effective and well-tolerated. Usually taken long-term — sometimes for life.

What it is used for

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)

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

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TAF: similar but with much less kidney and bone impact

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Entecavir: occasional nausea, fatigue

When to See a Doctor

Do not stop a prescribed medicine on your own. Speak to your doctor or pharmacist about side effects, interactions or any doubt, and seek urgent care for the serious warning signs above.

Drug class and examples

Nucleos(t)ide reverse transcriptase inhibitors for hepatitis B

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.

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.

Serious side effects — act on these

• 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 to stop or review

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 and 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 Saudi Arabia

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

• Should I be on TDF or TAF?

• When can I stop my hepatitis B medication?

• How often do I need ultrasound and AFP?

Source and review

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the SGA Patient Education Panel. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.

Frequently Asked Questions

What is Hepatitis B Antivirals (Tenofovir, Entecavir) used for?

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 does Hepatitis B Antivirals (Tenofovir, Entecavir) work?

What are the side effects of Hepatitis B Antivirals (Tenofovir, Entecavir)?

Common: 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.

When should I call my doctor about Hepatitis B Antivirals (Tenofovir, Entecavir)?

Contact your doctor promptly if you notice: Severe muscle pain or weakness, dark urine; New jaundice or worsening liver function; Persistent kidney function decline (TDF); Bone pain (TDF long-term).