Reviewed on 5/17/2022

What Is Abacavir and How Does It Work?

Abacavir is a prescription medication used for the treatment of HIV infection.

  • Abacavir is available under the following different brand names: Ziagen

What Are Dosages of Abacavir?

Adult and pediatric dosage

Oral solution

  • 20mg/mL


  • 300mg

HIV Infection

Adult dosage

  • 300 mg orally every 12 hours, OR
  • 600 mg orally every day

Pediatric dosage

  • Neonates/infants below 3 months: Safety and efficacy not established

Oral solution

  • Above 3 months: 8 mg/kg orally every 12 hoursr or 16 mg/kg/day; not to exceed 600 mg/day  


  • Available as a scored tablet; if unable to reliably swallow tablets, prescribe the oral solution
  • Weight between 14 kg to 19  kg: 150 mg orally every 12 hours, OR 300 mg every day
  • Weight between 20 to 24  kg: 150 mg in the  morning and 300 mg in the evening, OR 450 mg every day
  • Weight above 25 kg: 300 mg orally every 12 hours, OR 600 mg orally every day in combination with other antiretroviral agents

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Abacavir?

Common side effects of the Abacavir include:

  • nausea
  • tiredness
  • headache
  • vomiting
  • generally not feeling well
  • bad dreams or sleep problems
  • fever and chills
  • rash
  • nausea
  • ear, nose, or throat infections

Serious side effects of the Abacavir include:

  • severe upper stomach pain, nausea, vomiting, loss of appetite;
  • swelling around your midsection;
  • dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes);
  • unusual tiredness; or
  • chest pain or pressure, pain spreading to the jaw or shoulder.

Rare side effects of the Abacavir 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.


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What Other Drugs Interact with Abacavir?

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.

  • Abacavir has severe interactions with the following drug:
  • elvitegravir/cobicistat/emtricitabine/tenofovir DF
  • Abacavir has serious interactions with the following drugs:
  • Abacavir has moderate interactions with at least 20 other drugs.
  • Abacavir has minor interactions with the following drug:

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 or concerns.

What Are Warnings and Precautions for Abacavir?


  • Prior hypersensitivity reaction to abacavir
  • Presence of HLA-B*5701 allele
  • Moderate or severe hepatic impairment

Effects of drug abuse

  • None

Short-Term Effects

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

Long-Term Effects

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


  • Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, reported with nucleoside analogs, including abacavir; a majority of these cases have been in women; female gender and obesity may be risk factors; suspend dosing in those who develop 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
  • Immune reconstitution syndrome reported with combination ART; during the initial treatment phase, patients whose immune systems respond may develop an inflammatory response to indolent or residual opportunistic infections (eg, Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia [PCP], or tuberculosis); autoimmune disorders (eg, Graves disease, polymyositis, and Guillain-Barré syndrome) have also been reported
  • Use has been associated with increased risk of myocardial infarction in observational studies, but not in a meta-analysis of 26 randomized trials; caution with risks for coronary heart disease and minimizing modifiable risk factors, including smoking, hypertension, and hyperlipidemia, prior to use
  • Hypersensitivity
    • Before starting therapy, review medical history for prior exposure to any abacavir containing product
    • Increased risk of serious or fatal hypersensitivity reactions; patients with human leukocyte antigen allele, HLA-B*5701 are at a higher risk; do not restart abacavir following hypersensitive reaction; may cause hypotension, multiorgan failure, and/or death (see Contraindications and Black Box Warnings)
    • If a hypersensitivity reaction is ruled out, patients may restart therapy; rarely, patients who have stopped abacavir for reasons other than symptoms of hypersensitivity have also experienced life-threatening reactions within hours of reinitiating abacavir therapy; reintroduction to drug or any other abacavir-containing product recommended only if medical care can be readily accessed
    • A Medication Guide and Warning Card that provides information about recognition of hypersensitivity reactions should be dispensed with each new prescription and refill
  • Drug interaction overview
    • Methadone
      • In a trial of 11 HIV-1-infected subjects receiving methadone-maintenance therapy with abacavir 600 mg BID (twice the currently recommended dose), PO methadone clearance increased
      • This alteration will not result in a methadone dose modification in the majority of patients; however, an increased methadone dose may be required in a small number of patients

Pregnancy and Lactation

  • Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263
  • Available data from the APR show no difference in the overall risk of birth defects for abacavir compared with the background rate for birth defects of 2.7% in the Metropolitan Atlanta Congenital Defects Program (MACDP) reference population
  • In animal reproduction studies, oral administration of abacavir to pregnant rats during organogenesis resulted in fetal malformations and other embryonic and fetal toxicities at exposures 35 times the human exposure (AUC) at the recommended clinical daily dose; however, no adverse developmental effects were observed following oral administration of abacavir to pregnant rabbits during organogenesis, at exposures approximately 9 times the human exposure (AUC) at the recommended clinical dose
  • Lactation
    • Abacavir is present in human milk; there is no information on the effects of abacavir on breastfed infants or effects of the drug on milk production; because of the 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 abacavir


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