How does this medication work? What will it do for me?

Abacavir belongs to a class of medication called nucleoside reverse transcriptase inhibitors (NRTI). Reverse transcriptase is a part of the human immunodeficiency virus (HIV) which is required to infect cells and make more virus. Abacavir prevents reverse transcriptase from working properly. Abacavir is used in combination with other medications to reduce the HIV in your blood. HIV is the virus responsible for acquired immune deficiency syndrome (AIDS). HIV infection destroys CD4 (T) cells, which are important to the immune system. The immune system helps fight infections.

Abacavir does not cure AIDS and does not prevent it from being spread to others. It is used in combination with other anti-HIV medications to slow further growth or reproduction of HIV and it seems to slow down the destruction of the immune system.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Oral Solution

Each mL of clear-to-opalescent, yellowish, strawberry-banana-flavoured liquid, contains abacavir sulfate equivalent to abacavir 20 mg. Nonmedicinal ingredients: artificial strawberry and banana flavours, citric acid (anhydrous), hydrochloric acid, methylparaben, propylene glycol, propylparaben, saccharin sodium, sodium citrate (dihydrate), sodium hydroxide, and sorbitol solution.


Each yellow, biconvex, capsule-shaped, film-coated tablet, scored and imprinted with "GX 623" on both sides, contains abacavir 300 mg. Nonmedicinal ingredients: colloidal silicon dioxide, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polysorbate 80, sodium starch glycolate, titanium dioxide, triacetin, and yellow iron oxide.

How should I use this medication?

The recommended adult dose is 300 mg taken twice a day, or 600 mg taken once a day. The recommended dose for children and adolescents who weigh more than 30 kg is 300 mg taken twice a day. The recommended dose for children older than 3 months, who weigh less than 30 kg is based on body weight. The usual dose is 8 mg per kilogram of body weight taken 2 times a day. The maximum dose is 300 mg taken twice a day.

Abacavir must be taken in combination with other medications to treat HIV infection and it may be taken with food or on an empty stomach.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store both the tablet and the liquid forms of this medication at room temperature, and keep them out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take abacavir if you:

  • are allergic to abacavir or any ingredients of the medication
  • have moderately-to-severely reduced liver function

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • diarrhea
  • headache
  • lack of energy
  • loss of appetite
  • nausea
  • rash (without any other symptoms)
  • unusual tiredness or weakness
  • vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • changes in body fat locations (e.g., more body fat around the waist and less on the arms and legs; breast enlargement; lump of fat on the back near the shoulder area, also called "buffalo hump")
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • severe skin rash, including skin blistering and peeling (possibly with headache, fever, coughing, or aching before the rash begins)
  • signs of a serious allergic reaction: skin rash, or two or more of the following sets of symptoms:
    • fever
    • skin rash
    • nausea, vomiting, diarrhea, or abdominal pain
    • severe tiredness, achiness, or general ill feeling
    • sore throat, shortness of breath, or coughing
  • signs of lactic acidosis (muscle pain, nausea and vomiting, weakness, abdominal pain, difficulty breathing, rapid breathing, loss of appetite)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergic reactions: At the time of receiving this medication, make sure you are given a leaflet and warning card that will help you to recognize the signs and symptoms of allergy to abacavir. Abacavir causes an allergic reaction in approximately 8% of people. The symptoms usually appear within the first 6 weeks of treatment, but may occur at any time during therapy. People who suffer an allergic reaction to abacavir should never take the medication again. Some people are at higher risk of this allergic reaction. Your doctor can perform a blood test to see if you are at greater risk. If you have 2 or more of the following sets of symptoms, you may be experiencing a serious allergic reaction:

  • fever
  • nausea, vomiting, diarrhea, or abdominal pain
  • severe tiredness, aches, or general ill feeling
  • skin rash
  • sore throat, shortness of breath, or coughing

Fat redistribution: Over time, this medication may change how fat is distributed in your body and may change your body shape. You may notice increased fat in the upper back and neck, breast, around the back, chest, and stomach area; or loss of fat from the legs, arms, and face. The long-term effects of this are not known.

Heart attack: The use of abacavir is associated with an increased risk of heart attack. Due to this increased risk, if you have any of the following conditions or risk factors, tell your doctor about them:

  • diseases that increase your risk of heart disease, such as high blood pressure and diabetes
  • heart problems
  • smoking

Immune reconstitution syndrome: This medication may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. These symptoms occur soon after starting anti-HIV medication and can vary. They are thought to occur as a result of the immune system improving and being able to fight infections that have been present without symptoms (such as pneumonia, herpes, or tuberculosis). Report any new symptoms to your doctor immediately.

Lactic acidosis and enlarged liver: This medication can cause a rare but serious condition called lactic acidosis, together with an enlarged fatty liver. You may be more likely to experience these problems if you are female, obese, have known risk factors for liver disease, or have been taking medications such as abacavir for a long time. If you experience weakness, loss of appetite, sudden unexplained weight loss, abdominal pain, and difficulty breathing or rapid breathing, contact your doctor immediately or seek immediate medical attention.

Liver function: Abacavir is removed from the body by the liver and may cause liver problems. People with moderately-to-severely reduced liver function should not take abacavir. If you have liver disease or decreased liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine), contact your doctor immediately.

Stopping the medication: If you stop taking this medication, your HIV infection could get worse. Take the medication exactly as prescribed by your doctor, and do not stop taking the medication without checking with your doctor first.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication may pass into breast milk and affect your baby. Since HIV can be transmitted by breast milk, women who have HIV infection are cautioned against breast-feeding because of the risk of passing HIV to a baby who does not have the infection.

Children: The safety and effectiveness of this medication have not been established for children less than 3 months of age. The safety and effectiveness of once-daily dosing have not been established for adolescents and children less than 18 years of age and should therefore be avoided.

Seniors: Seniors are more likely to have reduced kidney, liver, and heart function, putting them at increased likelihood of experiencing side effects. They may require lower doses. The safety and effectiveness of once-daily doses of abacavir have not been studied for people more than 65 years of age and should therefore be avoided.

What other drugs could interact with this medication?

There may be an interaction between abacavir and any of the following:

  • alcohol
  • ganciclovir
  • methadone
  • protease inhibitors (e.g., amprenavir, lopinavir, ritonavir)
  • ribavirin
  • retinoids (medications that are chemically related to vitamin A; e.g., isotretinoin)
  • valganciclovir

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.