By Medically reviewed by hellodoktor

Generic Name: Zefdavir Brand Name(s): Zefdavir and Zefdavir.


What is zefdavir (lamivudine) used for?

Zefdavir is commonly used for treating HIV, the virus that can cause acquired immunodeficiency syndrome (AIDS). This medicine is not a cure for HIV or AIDS.

Zefdavir is a nucleoside analogue indicated in combination with other antiretroviral agents for the treatment of human immunodeficiency virus type 1 (HIV‑1) infection.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

How should I take zefdavir (lamivudine)?

Zefdavir comes as a tablet and liquid to take by mouth.

Continue to take lamivudine even if you feel well. Do not stop taking lamivudine without talking to your doctor.

How do I store zefdavir (lamivudine)?

Zefdavir is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store zefdavir in the bathroom or the freezer. There may be different brands of zefdavir that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush zefdavir down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using zefdavir (lamivudine)?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of zefdavir or other medications.
  • You have any other illnesses, disorders, or medical conditions.

Zefdavir should not be given to a child younger than 2 years old.

Zefdavir can pass into breast milk and may harm a nursing baby. You should not breastfeed while you are using zefdavir to treat hepatitis B. Women with HIV or AIDS should not breastfeed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

It is not known whether zefdavir will harm an unborn baby. HIV can be passed to your baby if you are not properly treated during pregnancy. Tell your doctor if you are pregnant or plan to become pregnant. Take all of your HIV medicines as directed to control your infection.

Is it safe during pregnancy or breastfeeding?

There isn’t enough information about the safety of using this medication during pregnancy and breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication.

Side effects

What side effects can occur from zefdavir (lamivudine)?

Common side effects may include:

  • Nausea
  • Diarrhea
  • Headache
  • General ill feeling
  • Cold symptoms such as stuffy nose, sneezing, sore throat, cough

Call your doctor at once if you have:

  • Pancreas problems such as severe pain in your upper stomach spreading to your back, nausea and vomiting, fast heart rate
  • Liver problems such as nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes)
  • Signs of a new infection such as fever, night sweats, swollen glands, mouth sores, diarrhea, stomach pain, weight loss
  • Chest pain (especially when you breathe), dry cough, wheezing, feeling short of breath
  • Cold sores, sores on your genital or anal area
  • Rapid heart rate, feeling anxious or irritable, weakness or prickly feeling, problems with balance or eye movement
  • Trouble speaking or swallowing, severe lower back pain, loss of bladder or bowel control
  • Swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence, loss of interest in sex

Get emergency medical help if you have signs of an allergic reaction such as hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with zefdavir (lamivudine)?

Zefdavir may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

These medications may include:

  • Atripla (efavirenz, emtricitabine, and tenofovir)
  • Combivir (lamivudine and zidovudine)
  • Complera (rilpivirine, emtricitabine, and tenofovir)
  • Emtriva (emtricitabine)
  • Epzicom (abacavir and lamivudine)
  • Stribild (cobicistat, elvitegravir, emtricitabine, and tenofovir)
  • Trizivir (abacavir, lamivudine, and zidovudine)
  • Truvada (emtricitabine and tenofovir)
  • Abacavir (Ziagen)
  • Didanosine (Videx)
  • Stavudine (Zerit)
  • Zalcitabine (Hivid)

Does food or alcohol interact with zefdavir (lamivudine)?

Zefdavir may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with zefdavir (lamivudine)?

Zefdavir may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

These health conditions may include:

  • Liver disease (especially hepatitis B if you are being treated for HIV)
  • Liver transplant
  • Kidney disease
  • A history of pancreatitis


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using zefdavir (lamivudine).

What is the dose of zefdavir (lamivudine) for an adult?

HIV Infection

The recommended dose is 300 mg PO qDay or 150 mg PO q12hr.

Chronic Hepatitis B

The recommended dose is 100 mg PO qDay.

What is the dose of zefdavir (lamivudine) for a child?

HIV Infection

Neonates (aged <4 weeks): The recommended dose is 2 mg/kg PO q12hr (for prevention of transmission or treatment).

Infants 1-3 months: The recommended dose is 4 mg/kg PO q12hr .

3 months -16 years: The recommended dose is 4 mg/kg PO q12hr or 8 mg/kg PO qDay; not to exceed 300 mg/day.

Chronic Hepatitis B

≥2 years: The recommended dose is 3 mg/kg PO qDay; not to exceed 100 mg/day.

How is zefdavir (lamivudine) available?

Zefdavir is available in the following dosage forms and strengths:

  • Tablets 100 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of zefdavir, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

msBahasa Malaysia


Review Date: April 30, 2017 | Last Modified: September 12, 2019

You might also like