ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.
Overview
It's usually taken long term.
What it's used for
- Chronic hepatitis B
How to take it
- Take it on an empty stomach, 2 hours after or before a meal.
- Don't stop on your own.
Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.
Side effects
Common side effects
- Headache
- Tiredness
- Dizziness
Call your provider todayYellow skin or eyes, dark urine, or pain in the upper right belly
Call your provider todayWeakness, fast breathing, or nausea (rare lactic acidosis)
Warnings
- Boxed warnings: hepatitis B flares after stopping; HIV resistance if HIV isn't treated.
Other medicines, foods, and alcohol
- Few interactions.
Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.
Pregnancy and breastfeeding
Talk with your provider.
Missed doses, overdose, and storage
If you miss a dose
Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.
If someone takes too much
Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.
Storing it
Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.
Conditions it's used for
Sources
- DailyMed: FDA drug label for Entecavir (U.S. National Library of Medicine)
- MedlinePlus: Drugs, herbs, and supplements
- FDA: Drugs@FDA
Last updated 2026-11-13.