Generic name: entecavir (en-TEK-a-vir)
Drug class: Nucleoside reverse transcriptase inhibitors (NRTIs)
Medically reviewed by Drugs.com. Last updated on Nov 2, 2021.
Severe acute exacerbations of hepatitis B have been reported in patients who have discontinued anti-hepatitis B therapy, including entecavir. Hepatic function should be monitored closely for at least several months after discontinuation. Initiation of anti-hepatitis B therapy may be warranted. Entecavir is not recommended in patients co-infected with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) who are not also receiving highly active antiretroviral therapy (HAART) because of the potential for the development of resistance to HIV nucleoside reverse transcriptase inhibitors. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogue inhibitors .
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Antiviral
Chemical Class: Guanosine Nucleoside Analog
Uses for entecavir
Entecavir is used to treat liver infection caused by hepatitis B virus. It belongs to the family of medicines called antivirals. Antivirals are used to treat infections that are caused by viruses. Entecavir will not cure the hepatitis B virus, but it will keep it from reproducing and causing more liver damage.
Entecavir is available only with your doctor's prescription.
Before using entecavir
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For entecavir, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to entecavir or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of entecavir in children younger than 2 years of age. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of entecavir in the elderly. However, elderly patients are more likely to have age-related kidney disease, which may require an adjustment in the dose for patients receiving entecavir.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other medical problems
The presence of other medical problems may affect the use of entecavir. Make sure you tell your doctor if you have any other medical problems, especially:
- Kidney disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
- Liver disease or
- Liver transplant, or history of—May increase chance for serious side effects.
Proper use of entecavir
Take entecavir exactly as directed by your doctor. Do not take it more often, and do not take it for a longer time than your doctor ordered. When your supply of entecavir is running low, contact your doctor or pharmacist ahead of time. Do not allow yourself to run out of entecavir. Also, do not stop taking entecavir without checking with your doctor first.
Read and follow carefully the patient information leaflet before starting entecavir treatment and each time you refill. Ask your doctor or pharmacist if you have any questions.
Take entecavir on an empty stomach (at least 2 hours after a meal and 2 hours before the next meal).
Measure the oral liquid correctly using the marked measuring spoon that comes with the package. Rinse the dosing spoon with water after each use.
The dose of entecavir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of entecavir. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage forms (solution or tablets):
- For chronic hepatitis B infection:
- Adults and children 16 years of age and older—0.5 to 1 milligram (mg) or 10 to 20 milliliters (mL) once per day.
- Children 2 years of age and older weighing more than 30 kilograms (kg)—0.5 to 1 milligram (mg) or 10 to 20 milliliters (mL) once per day.
- Children 2 years of age and older weighing 10 to 30 kg—dose is determined by body weight, usually between 3 to 20 milliliters (mL) once a day.
- Children younger than 2 years of age—Use and dose must be determined by your doctor.
- For chronic hepatitis B infection:
If you miss a dose of entecavir, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using entecavir
It is very important that your doctor check your or your child's progress at regular visits. This will allow your doctor to see if the medicine is working properly. Blood tests may be needed to check for unwanted effects.
It is important to tell your doctor if you become pregnant. Your doctor may want you to join a pregnancy registry for patients taking entecavir.
If you have or get HIV (human immunodeficiency virus) infection, be sure to discuss your treatment with your doctor. If you are taking entecavir to treat chronic hepatitis B and are not taking medicines for your HIV at the same time, some HIV treatments that you take in the future may be less likely to work. Your doctor may need you to get an HIV test before you start taking entecavir and anytime after that when there is a chance you were exposed to HIV. Entecavir will not help your HIV infection.
Two rare but serious reactions to entecavir are lactic acidosis (too much acid in the blood) and liver toxicity, which includes an enlarged liver. These are more common if you are female, very overweight (obese), or have been taking anti-HIV medicines for a long time. Call your doctor right away if you or your child feel tired, weak, dizzy, or nauseated, if you vomit or have stomach pain, dark urine, light-colored stools, unusual muscle pains, trouble with breathing, or if your skin or eyes turn yellow.
Liver disease may become worse if treatment with entecavir is stopped. Do not stop taking entecavir unless your doctor tells you to stop.
Treatment with entecavir has not been shown to decrease the chance of giving hepatitis B virus infection to other people through sexual contact or blood contamination.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Entecavir side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Incidence not known
- Abdominal or stomach discomfort
- decreased appetite
- difficulty with swallowing
- fast heartbeat
- fast, shallow breathing
- general feeling of discomfort
- hives, itching, or rash
- muscle pain or cramping
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- right upper abdominal or stomach pain and fullness
- tightness in the chest
- unusual tiredness or weakness
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Acid or sour stomach
- stomach discomfort, upset, or pain
- Trouble sleeping
- Unusual drowsiness
Incidence not known
- Hair loss
- thinning of the hair
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about entecavir
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- 2 Reviews
- Drug class: nucleoside reverse transcriptase inhibitors (NRTIs)
- Other brands
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