Reviewed on 3/28/2022

What Is Lamivudine and How Does It Work?

Lamivudine is a prescription medication used for the treatment of HIV infection and chronic hepatitis B.

  • Lamivudine is available under the following different brand names: Epivir, Epivir HBV, 3TC

What Are Dosages of Lamivudine?

Adult and pediatric dosage


  • 100mg (Epivir HBV)
  • 150mg (Epivir)
  • 300mg (Epivir)

Oral solution

  • 5mg/mL (Epivir HBV)
  • 10mg/mL (Epivir)

HIV Infection

Adult dosage

  • Epivir: 300 mg orally every day or 150 mg orally every 12 hours

Pediatric dosage

  • Epivir oral solution
    • Neonates (aged below 4 weeks): 2 mg/kg orally every 12 hours (for prevention of transmission or treatment)
    • Above 1 month: 4 mg/kg orally every 12 hours 
    • Above 3 months: 5 mg/kg orally every 12 hours or 10 mg/kg orally every day; not to exceed 300 mg/day
    • May switch to once-daily dosing after age 3 years in clinically stable patients with undetectable viral load and stable CD4 count (NIH HIV guidelines)
  • Epivir tablet
  • Weight-based dosing
    • 14 to 19 kg: 75 mg orally every 12 hours, OR 150 mg every day
    • 20 to 24 kg: 75 mg in the morning and 150 mg orally in the evening, OR 220 mg every day
    • Above 25 kg: 150 mg orally every 12 hours OR 300 mg orally every day
    • The NIH pediatric HIV treatment guideline (March 2016) does not recommend initiating once-daily lamivudine liquid formulation for HIV-infected infants and young children

Chronic Hepatitis B

Adult dosage

  • Epivir HBV: 100 mg orally every day

Pediatric dosage

  • Children below 2 years: Safety and efficacy not established
  • Children above 2 years: 3 mg/kg orally every day; not to exceed 100 mg/day

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Lamivudine?

Common side effects of Lamivudine include:

  • nausea,
  • diarrhea,
  • headache,
  • fever,
  • tiredness,
  • general ill feeling,
  • ear pain or full feeling,
  • trouble hearing,
  • drainage from the ear,
  • fussiness in a child,
  • stuffy nose,
  • sneezing,
  • sore throat, and
  • cough.

Serious side effects of Lamivudine include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • unusual muscle pain,
  • stomach pain,
  • vomiting,
  • irregular heart rate,
  • dizziness,
  • feeling cold,
  • weakness,
  • tiredness,
  • severe pain in the upper stomach spreading to the back,
  • nausea,
  • fast heart rate,
  • swelling around the midsection,
  • right-sided upper stomach pain,
  • loss of appetite,
  • dark urine,
  • clay-colored stools,
  • yellowing of the skin or eyes (jaundice),
  • fever,
  • night sweats,
  • swollen glands,
  • cold sores,
  • cough,
  • wheezing,
  • diarrhea,
  • weight loss,
  • trouble speaking or swallowing,
  • problems with balance or eye movement,
  • prickly feeling,
  • swelling in the neck or throat (enlarged thyroid),
  • menstrual changes, and
  • impotence.

Rare side effects of Lamivudine include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Lamivudine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Lamivudine has severe interactions with the following drugs:
    • elvitegravir/cobicistat/emtricitabine/tenofovir DF
    • emtricitabine
  • Lamivudine has serious interactions with the following drugs:
    • cabotegravir
    • sorbitol
    • tafenoquine
    • trilaciclib
  • Lamivudine has moderate interactions with at least 24 other drugs.
  • Lamivudine has minor interactions with the following drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Lamivudine?


  • Hypersensitivity

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Lamivudine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Lamivudine?”


  • Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, are reported with the use of nucleoside analogs, including lamivudine; a majority of these cases have been in women; female sex and obesity may be risk factors for the development of lactic acidosis and severe hepatomegaly with steatosis in patients treated with antiretroviral nucleoside analogs; suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity, which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations
  • Exacerbation of hepatitis B in HBV/HIV coinfected patients may occur on discontinuation
  • Risk of immune reconstitution syndrome if used in combination with other antiretroviral drugs
  • Discontinue immediately if signs or symptoms of pancreatitis occur in patients with a history of pancreatitis
  • EPIVIR-HBV is not appropriate for patients co-infected with HBV and HIV-1; if a patient with unrecognized or untreated HIV-1 infection is prescribed EPIVIR-HBV for treatment of HBV, the rapid emergence of HIV-1 resistance is likely to result because of subtherapeutic dose and inappropriate use of monotherapy for HIV-1 treatment
  • To reduce the risk of resistance in patients receiving monotherapy, consider a switch to an alternative regimen if serum HBV DNA remains detectable after 24 weeks of treatment; optimal therapy should be guided by resistance testing
  • Patients with HIV-1 infection should receive only dosage forms of lamivudine appropriate for the treatment of HIV-1
  • The emergence of lamivudine-resistant HBV variants associated with lamivudine-containing antiretroviral regimens reported
  • Concomitant administration of emtricitabine with lamivudine-containing products is not recommended
  • Hepatic decompensation (some fatal) reported in HIV-1/HCV co-infected patients receiving interferon and ribavirin-based regimens; monitor for treatment-associated toxicities; discontinue therapy as medically appropriate and consider dose reduction or discontinuation of interferon alfa, ribavirin, or both
  • Use with caution in pediatric patients with a history of pancreatitis or other significant risk factors for pancreatitis; discontinue treatment as clinically appropriate

Lower Virologic Suppression Rates and Increased Risk of Viral Resistance with Oral Solution

  • Pediatric subjects who received lamivudine (Epivir) oral solution concomitantly with other antiretroviral oral solutions at any time in the ARROW trial had lower rates of virologic suppression, lower plasma lamivudine exposure, and developed viral resistance more frequently than those receiving lamivudine (Epivir) tablets; lamivudine (Epivir) scored tablet is the preferred formulation for HIV-1-infected pediatric patients who weigh at least 14 kg and for whom a solid dosage form is appropriate; consider more frequent monitoring of HIV-1 viral load when treating with lamivudine (EPIVIR) oral solution

Pregnancy and Lactation

  • A pregnancy registry has been established to monitor maternal-fetal outcomes of women exposed to lamivudine: 1-800-258-4263
  • Available data from the APR show no difference in the overall risk of birth defects for lamivudine or zidovudine compared with the background rate for birth defects of 2.7% in the Metropolitan Atlanta Congenital Defects Program (MACDP) reference population; APR uses the MACDP as the U.S. reference population for birth defects in the general population; MACDP evaluates women and infants from a limited geographic area and does not include outcomes for births that occurred at less than 20 weeks gestation; rate of miscarriage is not reported in the APR


  • The Centers for Disease Control and Prevention recommend that HIV-1-infected mothers in the United States not breastfeed infants to avoid risking postnatal transmission of HIV-1 infection; lamivudine is present in human milk; there is no information on the effects of lamivudine or zidovudine on breastfed infants or effects of drugs on milk production; because of potential for (1) HIV-1 transmission (in HIV-negative infants), (2)developing viral resistance (in HIV-positive infants), and (3) serious adverse reactions in a breastfed infant, instruct mothers not to breastfeed if they are receiving therapy

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