An HIV Information Site & HIV Educational Resource Site (HIS & HERS)

Ziagen - abacavir

General Information Abacavir is almost always used as one component of a multidrug combination to suppress the human immunodeficiency (HIV) viral load.

Abacavir is one of the most potent antiviral drugs.  It is generally easy to take and very well tolerated.

Abacavir works by inhibiting the formation of HIV genetic material.  It is classified as a nucleoside reverse transcriptase inhibitor (NRTI) or "nuke" for short.


The usual dose is 300 mg twice a day.  This may be taken with or without food.

Your dose might be reduced if you have kidney failure or weak kidneys.

(this refers to your willingness, ability, and actual performance in taking your medications)

For further information and tips on adherence, go to the Adherence section of this site.

As with any antiviral drug or antibiotic, try not to ever miss a dose.  If you miss a dose and notice that you have done so within a few hours of its scheduled time, you may take the dose as usual and take the next dose at its regular time.

Never change the dose of this antiviral medication without speaking to your healthcare provider first.

If you miss more than one dose, look at the reasons why you missed them and come up with a plan to avoid it in the future.  For example, if you fell asleep too early, take the medicine earlier in the evening, with your later meal, set an alarm, or have someone appointed to wake you up for your medicine.  

It is strongly recommended that you use weekly pill boxes and arrange all of your doses a week in advance.  Also buy a small pill box so that you can carry a dose or two of your medicines with you in case you are away from home.

Possible Side Effects
The package insert for most drugs including abacavir is often overwhelming and scary with perhaps an overemphasis on side effects.  We have summarized the important and more common problems here.

Most people take abacavir without many side effects.   Usually you will see a healthcare provider and have blood drawn in the first 2-4 weeks to look for the good effects of abacavir as well as any side effects.

Possible side effects include mild nausea (that usually gets better,) headache, muscle aches, liver problems, or problems with blood cells.  Remember most people will not have ANY side effects.

Approximately 5% of patients who take abacavir develop allergy or "hypersensitivity" to it.  This is a well-recognized and easy to treat situation.  The allergic symptoms usually consist of SEVERAL of the following that always get worse as you take the drug: fever, body rash, cough, diarrhea, and nausea that gets worse.  These symptoms may occur with other problems such as flu, food poisoning and allergies to other drugs.  Therefore you should remember to inform your healthcare provider of any of these symptoms that tend to get worse and worse or more numerous as you continue to take abacavir.  It is very important that you do not stop the abacavir unless instructed to by your healthcare provider or someone who is familiar with abacavir.

If you have been diagnosed with hypersensitivity to abacavir, you must never take it again or you may die.

All drugs of this class can cause or contribute to abnormal fat redistribution characterized by thinning of the face, arms, or legs.  In most cases this would be also accompanied by elevated cholesterol levels, elevated triglyceride levels, and perhaps a tendency to develop diabetes.  Abacavir does not seem to cause these problems very often.

Rarely, a build-up of (lactic) acid may occur due to taking medications of this type.  Persons taking multiple nukes (NRTIs), those taking d4T (stavudine, Zerit), those on the combination of d4T (stavudine, Zerit) and ddI (didanosine, Videx), and those persons with hepatitis C are the most likely to encounter this rare, but potentially fatal problem.  The symptoms are vague but troublesome: nausea, vomiting, muscle aches, weakness, turning yellow with jaundice, and just feeling plain bad.

Report to you healthcare provider or go to an Emergency Room if you have severe side effects, increasing side effects, shortness of breath, abdominal pain, uncontrollable diarrhea, weakness, jaundice (eyes and skin turn yellow,) muscle pain, skin rash, nausea and vomiting so that you cannot hold down your food and liquids.
You can download this handout in PDF format by clicking HERE.