NZ Formulary



What does it do?

Entecavir is used to treat Hepatitis B.

How should you take it?

Take entecavir as directed with a glass of water. It is very important to take entecavir regularly. If you often forget to take entecavir, it may not work as well.
Some people may need to take entecavir on an empty stomach (2 hours before or 2 hours after food). Check with your doctor.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Tiredness or weakness

Dizziness, headache


Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Tell your doctor if you have kidney problems or HIV.
  • Use reliable contraception while taking entecavir. If you plan to become pregnant, or find you are pregnant, discuss this with your doctor. Tell your doctor if you are breastfeeding.
  • You will need regular blood tests while taking entecavir to check your viral load and liver.
  • Very rarely, entecavir can cause a serious condition called lactic acidosis. Stop taking entecavir and tell your doctor immediately if you are feeling very unwell or unusually tired, or if your breathing becomes faster than normal.
  • Do not stop taking entecavir without talking to your doctor first.