Entecavir

Pronunciation: en-TEK-a-veer.

Generic name
entecavir
Drug class
Nucleoside analogue antiviral (guanosine analogue, hepatitis B virus polymerase inhibitor)
Form
Tablet (0.5 mg or 1 mg) or oral solution (0.05 mg/mL)
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Generic entecavir (ENTECAVIR APO, ENTECAVIR ML, ENTECAVIR-WGR) -- original Baraclude brand cancelled 28 June 2024, but generics remain currently registered (5) · Full directory

What entecavir is and how it works

Entecavir is a prescription-only antiviral medicine that reduces hepatitis B virus replication, used for long-term (chronic) hepatitis B infection. It works by blocking an enzyme the virus needs to copy itself. (1)

Take entecavir exactly as your prescriber directs, on an empty stomach. This is typically a long-term treatment -- never stop taking it without talking to your prescriber first, even if you feel well, because stopping can trigger a serious flare-up of your hepatitis B that needs close medical monitoring.

Mechanism of action: how entecavir works

Entecavir is a guanosine nucleoside analogue that is phosphorylated intracellularly to its active triphosphate form, which competitively inhibits hepatitis B virus polymerase, blocking priming, reverse transcription, and DNA synthesis, thereby suppressing viral replication. (1) (2)

What entecavir is used for

Chronic hepatitis B virus infection

Used to treat long-term (chronic) hepatitis B virus infection in adults and, in some countries, children aged 2 years and older, who have evidence of active viral replication and either persistently elevated liver enzymes or active liver disease seen on biopsy. (1) (3)

Before taking entecavir

Do not take / not appropriate for

  • Do not take entecavir if you have had a hypersensitivity (allergic) reaction to entecavir or any of its ingredients. (all countries) (1) (2)

Tell your clinician about

  • Whether you have HIV infection, or any risk of undiagnosed HIV infection -- this affects whether entecavir alone is appropriate for you.
  • Any history of liver disease, including decompensated liver disease, which can affect your risk of lactic acidosis.
  • Any kidney problems -- your dose may need to be adjusted.
  • All other medicines you take, especially any that can affect kidney function.
  • Pregnancy, plans for pregnancy, or breastfeeding.
  • If you are a lamivudine-experienced or lamivudine-refractory patient, since this can affect your treatment plan and resistance risk.
(1) (2)

How to take entecavir

  • Take entecavir on an empty stomach -- at least 2 hours after and 2 hours before your next meal.
  • Take it exactly as prescribed, at the same time each day.
  • Continue taking entecavir for as long as your prescriber recommends, even if you feel well -- hepatitis B treatment is usually long-term.
  • Never stop taking entecavir without first discussing it with your prescriber, because stopping can trigger a serious hepatitis flare that needs close monitoring.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

If you miss a dose, take it as soon as you remember on the same day, then continue your normal schedule the next day. Do not take a double dose. Contact your prescriber if you miss doses often, since missed doses can affect how well the medicine controls your hepatitis B.

Overdose

Seek urgent medical attention if you think you or someone else has taken too much entecavir. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Headache.

What to notice: Headache.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Fatigue (tiredness).

What to notice: Fatigue (tiredness).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Dizziness.

What to notice: Dizziness.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Nausea.

What to notice: Nausea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Serious warnings

Signs of a hepatitis flare after stopping entecavir (or missing doses long-term) — boxed_warning

Symptoms: Worsening tiredness, loss of appetite, nausea, vomiting, yellowing of the skin or eyes (jaundice), dark urine, or abdominal pain, appearing weeks to months after stopping treatment.

Action: Never stop entecavir without your prescriber's guidance. If you do stop for any reason, your prescriber needs to monitor your liver closely, with clinical checks and blood tests, for at least several months afterward, since severe and sometimes fatal flares have occurred. (1) (2) (4) (6)

Signs of lactic acidosis — boxed_warning

Symptoms: Unusual tiredness or weakness, unusual muscle pain, trouble breathing, stomach pain with nausea and vomiting, feeling cold (especially in the arms and legs), dizziness, or a fast or irregular heartbeat.

Action: Seek emergency medical help immediately -- lactic acidosis is a medical emergency, and it can occur with entecavir and similar antiviral medicines, sometimes with severe liver enlargement and fatty change. (1) (2) (4)

Undiagnosed or untreated HIV infection while taking entecavir — high caution

Symptoms: No specific symptoms -- this is a risk related to unrecognised or untreated HIV coinfection rather than a symptom to watch for.

Action: Tell your prescriber if you have any risk factors for HIV or have not been tested. Entecavir alone is not recommended if you have both HIV and hepatitis B and are not also on effective HIV treatment, because resistance to certain HIV medicines could develop. (1) (2) (6)

Interactions

  • Medicines that reduce kidney function or compete for elimination by the kidneys may increase entecavir levels in your blood -- tell your prescriber about all medicines you take. (1) (2)
  • No clinically significant interactions have been found with lamivudine, adefovir, or tenofovir. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Limited data from pregnancy registries are not enough to fully assess the risk. Animal studies did not show developmental problems at clinically relevant exposure levels. Discuss the benefits and risks with your prescriber if you are pregnant or planning pregnancy. (1) (2) (3) (4) (5) (6)

Breastfeeding

It is not known whether entecavir passes into human breast milk. Discuss with your prescriber, who may advise against breastfeeding during treatment. (1) (2) (3) (4) (5) (6)

Children

Approved for children aged 2 years and older with compensated liver disease in some countries -- dosing is weight-based and set by a specialist. (1) (2) (3) (4) (5) (6)

Elderly

No specific age-based dose adjustment beyond the standard kidney-function-based adjustment, but kidney function should be checked, since it commonly declines with age. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

No dose adjustment is needed for compensated or decompensated liver disease based on liver function alone, but decompensated liver disease may increase the risk of lactic acidosis -- your prescriber will monitor you closely. (1) (2) (3) (4) (5) (6)

Renal_impairment

Dose or dosing frequency is adjusted if your creatinine clearance is below 50 mL/min, including if you are on haemodialysis or peritoneal dialysis. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • HIV status (testing or risk assessment)
  • Baseline liver function and hepatitis B viral markers
  • Kidney function (creatinine clearance)

During treatment

  • Regular liver function tests and hepatitis B viral load monitoring.
  • Kidney function monitoring, especially in those with existing kidney problems.
  • Watching for signs of lactic acidosis, especially in people with decompensated liver disease.
(1) (2) (4)

Storage

Store at room temperature, away from moisture. Keep the oral solution's dosing device with the medicine. Keep out of the reach of children.

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information and UK SmPC; verify against the current full label before prescribing.

United States

Indication: Chronic hepatitis B virus infection

Dose summary: 0.5 mg once daily in nucleoside-naive patients with compensated liver disease; 1 mg once daily in lamivudine-refractory/experienced patients or those with decompensated liver disease. Dose/frequency reduced for creatinine clearance under 50 mL/min. Taken on an empty stomach.

Renal context: Dose adjustment required for creatinine clearance under 50 mL/min, including haemodialysis and CAPD patients. (1)

United Kingdom

Indication: Chronic hepatitis B virus infection

Dose summary: Individualised by treatment history and liver function; dose adjustment required for creatinine clearance under 50 mL/min. Post-treatment hepatic monitoring recommended for at least 6 months.

Renal context: Dose adjustment recommended for creatinine clearance under 50 mL/min, including haemodialysis/CAPD. (2)

Mechanism of action

Hepatic guidance

No dose adjustment based on hepatic function alone; decompensated liver disease may raise the risk of lactic acidosis, warranting closer monitoring.

Overdose note

Limited overdose data; manage supportively with monitoring for adverse reactions. (1) (2)

Frequently asked questions

Is entecavir (Baraclude) available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, entecavir is authorised and available in all of these regions, either as the brand Baraclude or as generic entecavir. In Australia the original Baraclude brand has been discontinued, but generic entecavir remains currently available. (1) (3) (2) (4) (5) (6)

Can I just stop taking entecavir if I feel better?

No -- never stop entecavir without talking to your prescriber first. Stopping hepatitis B treatment, including entecavir, has been linked to severe and sometimes fatal flares of hepatitis. If your prescriber does decide to stop your treatment, they will arrange close monitoring of your liver, including blood tests, for at least several months afterward. (1) (2) (4)

How is entecavir taken, and does kidney function affect the dose?

Entecavir is taken on an empty stomach, at least 2 hours before or 2 hours after a meal. The exact dose depends on whether you have taken lamivudine before, and whether your liver disease is compensated or decompensated. If your kidney function is reduced (creatinine clearance under 50 mL/min), your prescriber will adjust the dose or how often you take it. (1)

What is the mechanism of action of entecavir?

Entecavir is a guanosine nucleoside analogue that is phosphorylated intracellularly to its active triphosphate form, which competitively inhibits hepatitis B virus polymerase, blocking priming, reverse transcription, and DNA synthesis, thereby suppressing viral replication. (1) (2)

What is the generic name of Entecavir?

The generic name is entecavir. (1)

What class of drug is entecavir?

Entecavir is classed as: Nucleoside analogue antiviral (guanosine analogue, hepatitis B virus polymerase inhibitor). (1)

References

  1. BARACLUDE (entecavir) tablets and oral solution -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information, Bristol-Myers Squibb (E.R. Squibb & Sons, L.L.C.) · United States · accessed 2026-07-29 · source 1
  2. Baraclude 0.5 mg film-coated tablets -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Bristol-Myers Squibb · United Kingdom · accessed 2026-07-29 · source 2
  3. Baraclude European Public Assessment Report (EPAR)European Medicines Agency (EMA) · European Union · accessed 2026-07-29 · source 3
  4. Baraclude (entecavir) Tablets 0.5 mg -- Product MonographHealth Canada product monograph, Bristol-Myers Squibb Canada · Canada · accessed 2026-07-29 · source 4
  5. Generic entecavir products -- current ARTG registrations (brand Baraclude discontinued)Therapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 5
  6. Entecavir Tablets -- New Zealand Data SheetMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-29 · source 6

Brand names by country

Single-ingredient entecavir names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • BARACLUDE.5 mg, 1 mg, .05 mg/mL · e.r. squibb & sons, l.l.c.

United Kingdom

  • Baraclude (2)MHRA licensed emc smpc confirmed · 0.5 mg, 1 mg tablet, 0.05 mg/mL oral solution · Bristol-Myers Squibb

Canada

  • BARACLUDE

Australia

  • Generic entecavir (ENTECAVIR APO, ENTECAVIR ML, ENTECAVIR-WGR) -- original Baraclude brand cancelled 28 June 2024, but generics remain currently registered (5)TGA ARTG registered confirmed brand discontinued generics current · 0.5 mg · Arrotex Pharmaceuticals Pty Ltd; GM Pharma International Pty Ltd

New Zealand

  • Generic entecavir (multiple manufacturers including Juno, Teva, Sandoz, Rex) (6)Medsafe approved confirmed · 0.5 mg, 1 mg · multiple generic manufacturers
View brands in additional countries.

European Union

Baraclude; Entecavir Viatris (generic) (3)

This page provides general reference information about entecavir and is not a substitute for advice from the prescriber managing your treatment. All dosing and treatment decisions, including any decision to stop treatment, should be made with your prescriber.

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