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Entecavir

Warning

Rarely, entecavir may cause serious (possibly fatal) liver problems and lactic acid build-up in the blood (lactic acidosis). Get medical help right away if you have any of the following symptoms: nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine, unusual tiredness/weakness, deep/fast breathing, unusual drowsiness, unusual muscle pain, feeling cold in your arms/legs, fast/irregular heartbeat. These side effects may occur more often in women and obese patients.

Your hepatitis B infection may get worse if you stop taking entecavir. Do not stop this medication without talking to your doctor. Your doctor will do blood tests to check your liver for several months after you stop entecavir.

This medication is not recommended if you have both HIV and hepatitis B and are not receiving effective treatment for HIV. This drug does not treat HIV, and it can cause certain HIV medications to become ineffective. Get an HIV test before starting this medication, and get tested again anytime you may have become infected. Consult your doctor for more details.

Precautions

Before taking entecavir, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: HIV infection, kidney disease, other hepatitis B drugs taken in the past.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Alcohol may also worsen liver problems. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

To decrease your risk of spreading hepatitis B to others, always use an effective barrier method (latex or polyurethane condoms/dental dams) during all sexual activity. Consult your doctor or pharmacist for more details.

During pregnancy, this medication should be used only when clearly needed. It is not known if this medication helps to prevent the hepatitis B virus from passing from the mother to the baby. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. If you have HIV, breast milk may transmit HIV. Consult your doctor before breastfeeding.

Side Effects

See also Warning section.

Headache, tiredness, dizziness, or nausea may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

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Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

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Information expires December 2025.