Hepsera (Adefovir) - Oral


Hepsera (adefovir) contains the following boxed warnings.

Fatty liver and worsening hepatitis: If you have liver problems, you might experience appetite loss, dark-colored urine, light-colored stools, upper right-sided stomach pain, and yellowing of the eyes or skin.

HIV resistance: Before treating hepatitis B, your healthcare provider will request blood work to test for an HIV infection. If you have both infections, your healthcare provider will appropriately treat both conditions simultaneously. Only treating hepatitis B—when you also have an HIV infection—can make HIV resistant to treatment and hard to treat.

Kidney toxicity: If you’re having kidney problems, symptoms may include appetite loss, blood in your urine, concentration difficulties, cramping muscles, dry or itchy skin, eye puffiness, foamy urine, low energy, sleeping troubles, swollen feet or ankles, and tiredness.

Lactic acidosis: If you’re experiencing lactic acidosis, you may notice several symptoms, including breathing difficulties, dizziness, fast heartbeat, irregular heartbeat, lightheadedness, tiredness, unusual muscle pain, and weakness. You might also feel cold in your arms and legs. Some people also have stomach pain with nausea and vomiting.

What Is Hepsera?

Hepsera (adefovir) is a nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) used to treat chronic (long-term) liver infection with hepatitis B virus (HBV). The medication can be used in people aged 12 years and older.

Hepsera prevents the virus from making more copies of itself by inserting itself into the viral deoxyribonucleic acid (DNA) genetic material and making this DNA useless.

This medication is available as a prescription tablet.

Drug Facts

Generic Name: Adefovir

Brand Name: Hepsera

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Antiviral

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Adefovir

Dosage Form: Tablet

What Is Hepsera Used For?

The hepatitis B virus (HBV) causes an infection that can lead to liver inflammation (swelling). The virus will go away in some people after an acute (short-term) infection, with symptoms lasting up to six months. Symptoms of this type of infection may include:

  • Appetite loss
  • Dark yellow-colored urine
  • Fever
  • Joint pain
  • Nausea or vomiting
  • Stomach pain
  • Stools that are gray or clay in color
  • Tiredness or low energy
  • Yellowing of the skin and eyes (jaundice)

However, if the body can’t fight off and clear out the virus, the infection will become chronic (long-term)—with some people having no symptoms until they experience complications. Complications may include cirrhosis, liver failure, or liver cancer.

As a result, screening for hepatitis B infection is so important. Once the healthcare provider is aware of a chronic hepatitis B infection, there are available treatments—like Hespera. However, Hespera isn’t a first-line option. Compared to other treatment choices, HBV is more likely to become resistant to Hepsera.

Hepsera (Adefovir) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Hepsera?

Take Hepsera by mouth once daily with or without food. 

However, depending on your kidney function, your healthcare provider can recommend that you take Hepsera less frequently. If you have any questions, talk with your healthcare provider or pharmacist.


With Hepsera being a non-controlled medication, your healthcare provider can approve enough refills for one year from the originally written date on the prescription.

When you receive the medication from the pharmacy, store the medication at room temperature, which is 77 degrees Fahrenheit (F) with a safety temperature range of 59 degrees to 86 degrees F.

If you intend to bring Hepsera with you on your travels, prepare beforehand by becoming familiar with the regulations of your final destination. Make a copy of your Hepsera prescription, and keep Hepsera in its original container—with your name—from the pharmacy.

How Long Does Hepsera Take to Work?

You and your healthcare provider may notice an improvement in your medical condition within 48 weeks of Hepsera treatment.

What Are the Side Effects of Hepsera?

Like many medications, Hepsera does have side effects.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

Common side effects with Hepsera may include:

Severe Side Effects

The severe side effects of Hepsera are also its boxed warnings, which include:

  • Human immunodeficiency virus (HIV) resistance: HIV treatment typically requires a combination of multiple medications to prevent resistance to treatment. Adefovir works similarly to some HIV treatment options. If you’re treating HBV and an unknown HIV infection with only adefovir, HIV might become resistant to treatment.
  • Fatty liver and lactic acidosis: Treatment with nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)—like Hepsera—is linked to fatty liver development and lactic acidosis. Lactic acidosis can be severe with symptoms of low blood pressure and little oxygen in the body.
  • Kidney toxicity: Long-term use of Hepsera can lead to kidney toxicity. People with kidney impairment have a higher risk of this side effect.
  • Worsening hepatitis: If you stop Hepsera, you might experience worsening of your hepatitis infection—which can be severe.

If you suspect that you’re experiencing any of these serious side effects, seek immediate medical attention.

Long-Term Side Effects

People taking Hepsera for 240 weeks (over four years) experience similar side effects to people who only took the medication for 48 weeks. However, if you take Hepsera for a long time, you are at a higher risk of kidney toxicity, especially if you already have some kidney impairment.

Report Side Effects

Hepsera may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Hepsera Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine 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 this medicine. 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 form (tablets):
    • For chronic hepatitis B infection:
      • Adults and children 12 years of age and older—10 milligrams (mg) once a day.
      • Children younger than 12 years of age—Use is not recommended.


In some instances, your healthcare provider may adjust your dosage of Hepsera or monitor you more closely while taking this medication.

People With Kidney Disease

Your healthcare provider will monitor your kidneys. If your kidneys aren’t working as well, your healthcare provider can make some adjustments—like recommending that you take Hepsera less frequently.

Pregnancy or Breastfeeding

If you’re taking Hepsera during pregnancy, consider registering in the Antiretroviral Pregnancy Registry (APR) by calling 1-800-258-4263. Based on the current data from the APR, there isn’t enough information to determine the effect of Hepsera on the fetus.

As for nursing, there is also limited effectiveness and safety data about Hepsera in nursing babies.

Talk to your healthcare provider if you have questions or concerns about taking Hepsera while pregnant or nursing.

Missed Dose

If you forgot to take your Hepsera dose, take it as soon as you remember. However, if it’s already the next day, skip the missed dose and take the following dose at your next scheduled time. Don’t try to take more than one dose within one day to make up for the missed dose.

Try to find ways to remember to take your Hepsera medication consistently. Forgetting too many doses too often might lead to a hepatitis B infection that’s resistant to treatment.

Overdose: What Happens If I Take Too Much Hepsera?

High doses of Hepsera might lead to symptoms of stomach upset or discomfort.

What Happens If I Overdose on Hepsera?

If you think you or someone else may have overdosed on Hepsera, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses, has a seizure, has trouble breathing, or can’t wake up after taking too much Hepsera, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

You should not use this medicine if you are also taking tenofovir (Viread®) or other medicines containing tenofovir (eg, Atripla®, Complera®, Stribild™, or Truvada®). Tell your doctor right away if you are using any of these medicines. Do not start using adefovir until your doctor tells you to.

If you have or get HIV infection, be sure to discuss your treatment with your doctor. If you are using this medicine to treat chronic hepatitis B, and are not taking medicine for your HIV infection at the same time, some HIV treatments may be less likely to work. You may need to get an HIV test before you start using this medicine, and again later if there is a chance you were exposed to HIV. This medicine will not help your HIV infection.

When this medicine is stopped, the liver disease (hepatitis) may become worse. Do not stop using adefovir unless your doctor tells you to. Be sure to keep all appointments with your doctor after you stop using this medicine. Blood tests will be needed to check your liver function.

Check with your doctor right away if you have more than one of the following: blood in the urine, change in frequency of urination or amount of urine, difficulty with breathing, drowsiness, increased thirst, loss of appetite, nausea or vomiting, swelling of the feet or lower legs, or weakness. These may be symptoms of a serious kidney problem.

Two rare but serious reactions to this medicine are lactic acidosis (build-up of acid in the blood) and liver toxicity, including 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 have stomach discomfort or cramping, nausea, vomiting, diarrhea, decreased appetite, muscle cramping or pain, unusual tiredness or weakness, trouble breathing, or a yellowish color in your skin or eyes.

Treatment with adefovir has not been shown to decrease the chance of giving hepatitis B virus infection to other people through sexual contact or by sharing needles. If you have any questions about this, check with your doctor.

What Are Reasons I Shouldn’t Take Hepsera?

If you had a severe allergic reaction to Hepsera or any of its components, avoid taking Hepsera.

Also, experts don’t recommend using antiviral medications like Hepsera if you have an acute hepatitis B infection.

What Other Medications Interact With Hepsera?

Your body uses the kidneys to get rid of Hepsera. Use caution with other medications that also clear out of the body through the kidneys. Medications that lower kidney function can also interact with Hepsera.

The drug's manufacturer also recommends against combining Hepsera and tenofovir medications.

What Medications Are Similar?

Like Hepsera, many of the chronic hepatitis B treatment options are in the nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) medication class, which include the following:

  • Entecavir
  • Lamivudine
  • Telbivudine
  • Tenofovir disoproxil fumarate
  • Tenofovir alafenamide

Of all the different NRTI medications, experts prefer entecavir and the tenofovir products.

Like Hepsera, lamivudine isn’t a first-line option because HBV can quickly become resistant to it—compared to other options. Telbivudine is also not a first-choice treatment selection. There is limited safety and effectiveness data on telbivudine in people who are Black or Hispanic.

Since all of these medications are NRTIs, they’re not typically taken together to treat chronic hepatitis B. Discuss your treatment options with your healthcare provider.

Frequently Asked Questions

  • Where is Hepsera available?

    Hepsera is available as a prescription from your healthcare provider. Chronic, or long-term, hepatitis B medications are typically available through specialty pharmacies—not the local retail pharmacy.

  • How much does Hepsera cost?

    Hepsera can generally be expensive without insurance coverage. However, it is available as the generic adefovir medication. 

    If cost is a concern, ask your healthcare provider or pharmacist about possible patient assistance programs.

  • How long do I need to take Hepsera?

    Experts recommend receiving long-term treatment if you have a chronic hepatitis B infection.

How Can I Stay Healthy While Taking Hepsera?

Receiving a diagnosis of chronic hepatitis B can understandably take a toll on your emotions.  

Consider taking the first step by learning more about chronic hepatitis B and sharing your condition with trusted loved ones—when you are comfortable. While this is a tough step, having a strong social support network is very important. In addition to friends and family, there are support groups. A mental health professional can also share coping strategies to help change how you feel, react, and think about your medical condition. Also, find ways to manage your stress.

In addition to taking care of yourself emotionally, taking care of yourself physically is very important. Regularly exercising and having healthy eating habits can slow down the worsening of your liver condition. Also, try to make sure that you get enough sleep on a nightly basis.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Hepsera label.

  2. MedlinePlus. Hepatitis B.

  3. National Institute of Diabetes and Digestive and Kidney Diseases. Hepatitis B.

  4. Terrault NA, Lok AS, McMahon BJ, et al. Update on prevention, diagnosis, and treatment and of chronic hepatitis B: AASLD 2018 hepatitis B guidance. Hepatology. 2018;67(4):1560-1599. doi:10.1002/hep.29800

  5. Wilkins T, Sams R, Carpenter M. Hepatitis B: screening, prevention, diagnosis, and treatment. Am Fam Physician. 2019;99(5):314-323.

  6. MedlinePlus. Lactic acidosis.

  7. MedlinePlus. Adefovir.

By Ross Phan, PharmD, BCACP, BCGP, BCPS
Ross is a writer for Verywell with years of experience practicing pharmacy in various settings. She is also a board-certified clinical pharmacist and the founder of Off Script Consults.