Sounds like 'en-tek-a-veer'

Key points about entecavir

  • Entecavir is used to treat infections caused by viruses such as hepatitis B infection.
  • Find out how to take it safely and possible side effects.
blue unaunahi tile generic
Print this page

Entecavir is used to treat long-term hepatitis B infection. It is called an antiviral medicine. Entecavir works by stopping the hepatitis B virus from multiplying and in this way reduces the amount of the virus in your body. It lowers the ability of the hepatitis B virus to infect new liver cells and improves the condition of your liver.

Most people who take entecavir achieve viral suppression, which means means the virus has been controlled and is at low (or undetectable) levels in your blood. However the virus is still present and it does not mean you have been cured. It does not prevent the spread of the virus to others through sexual contact or blood or body fluid contamination, such as sharing used needles. Read more about chronic hepatitis B.

In New Zealand entecavir is available as tablets (0.5 mg).

  • The usual dose of entecavir is 0.5 mg once a day.
  • Some people may need higher doses (1 mg once a day).
  • Your doctor will advise you how long to take entecavir for.
  • Always take your entecavir exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.

  • Swallow your entecavir tablet whole with a glass of water.
  • Entecavir is best taken on an empty stomach, at least 2 hours before or 2 hours after food.
  • Try taking your dose about the same time each day.
  • Limit or avoid alcohol while taking entecavir. Alcohol can increase the chances of side effects like dizziness. Also alcohol may worsen liver problems.   
  • If you forget to take your dose, take it as soon as you remember. But, if it is nearly time for your next dose, take your next dose at the usual time. Do not take double the dose.
  • Keep taking your entecavir tablets for the full time it has been prescribed, even if you feel well.
  • Blood tests: you will need regular blood tests while taking entecavir to check how well the medicine is working for you.

  • Are you pregnant, planning a pregnancy or breastfeeding?
  • Do you have problems with your kidneys?
  • Do you have HIV infection?
  • Are you taking any other medicines? This includes any medicines you buy without a prescription, such as herbal and complementary medicines.

If so, it’s important that you tell your doctor or pharmacist before you start entecavir. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care. 

Like all medicines, entecavir can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Lactic acidosis

Entecavir can very rarely cause a condition called lactic acidosis. You are at highest risk if you have kidney problems. Contact your doctor immediately if you are being sick (vomiting), feel very unwell, have muscle cramps, become unusually tired or feel short of breath and your breathing becomes faster than normal – these are the signs of lactic acidosis.

Side effects What should I do?
  • Nausea (feeling sick) 
  • Vomiting (being sick)
  • Indigestion
  • Diarrhoea (runny poos)
  • Headache
  • Feeling tired
  • Trouble sleeping
  • Dizziness
  • These are quite common when you first start taking entecavir and usually get better with time. 
  • Tell your doctor if troublesome.
  • Signs of an allergic reaction such as skin rash, itching, swelling of your lips, face and mouth or difficulty breathing
  • Tell your doctor immediately or ring HealthLine 0800 611 116.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

The following links have more information on entecavir.

Hepatitis B treatment(external link) Hepatitis Foundation, NZ
Entecavir(external link) New Zealand Formulary
Entecavir Sandoz(external link) Medsafe Consumer Information


  1. Entecavir(external link) New Zealand Formulary
  2. Hepatitis B – treatments now available for primary care(external link) BPAC, NZ, 2018

Free helplines

Healthline logo

Text 1737 Helpline logo

Logo with link to Māori Pharmacists website

Credits: Sandra Ponen, Pharmacist. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

Last reviewed:

Page last updated: