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# Hepatitis B antivirals

Oral antivirals that keep hepatitis B virus suppressed and protect the liver. Most people need them for life; stopping can cause a flare.

Updated 2026-11-01

## What they are

Medicines for chronic hepatitis B. WHO recommends tenofovir or entecavir; they slow cirrhosis and reduce liver cancer, but they rarely clear the virus, so most people continue them for life. Antivirals in pregnancy, together with the birth-dose vaccine, help prevent transmission to the baby.

## Mechanism of action

Hepatitis B virus copies its DNA through an RNA intermediate using its own polymerase with reverse transcriptase activity. Nucleoside and nucleotide analogues (entecavir, tenofovir, lamivudine, adefovir) are phosphorylated in the cell and block this polymerase. They do not remove the cccDNA that stays in the nucleus of infected liver cells, which is why the infection returns when treatment stops.

Target: HBV polymerase (reverse transcriptase)

## Key points

- First line (WHO): tenofovir or entecavir, both with a high barrier to resistance.
- Stopping any of them can trigger a severe hepatitis flare: liver tests are followed for months afterwards.
- Lamivudine-resistant virus is less sensitive to entecavir, and entecavir resistance then appears more easily.
- Before starting, HIV status is checked: a single HBV drug with activity against HIV in someone with untreated HIV selects HIV resistance.
- Entecavir and tenofovir are cleared by the kidneys; kidney function guides their use.

## Drugs in this class

- [**Entecavir** An oral first-line antiviral for chronic hepatitis B. It strongly suppresses the virus; stopping it can cause a severe… Hepatitis B virus polymerase (reverse transcriptase)](https://durgical.com/en/pharmacology/entecavir/)

## Others in the class

- Tenofovir disoproxil
- Tenofovir alafenamide
- Lamivudine
- Adefovir dipivoxil
- Telbivudine
- Bulevirtide (hepatitis D)

## Test yourself

Think of the answer, then tap the question to see it.

## Which two drugs does WHO recommend for chronic hepatitis B?

Tenofovir or entecavir.

## Why does hepatitis B usually come back when treatment stops?

The drugs block the viral polymerase but do not remove the cccDNA kept in the nucleus of liver cells.

## What can happen when a hepatitis B antiviral is stopped?

A severe, sometimes fatal, flare of hepatitis; liver tests are followed for months afterwards.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Hepatitis B](https://www.who.int/news-room/fact-sheets/detail/hepatitis-b) (World Health Organization, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 63 (McGraw Hill, 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J05AF) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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