Zidovudine, one of the medications in this product, can decrease bone marrow function, which may lead to low numbers of red and white blood cells. A low number of red blood cells can lead to anemia. A low number of white blood cells can decrease your body's ability to fight serious, life-threatening infections. These serious side effects occur more often in people with advanced HIV disease (AIDS). Get medical help right away if you develop any signs of anemia (such as unusual tiredness, fast breathing, pale skin, fast heartbeat) or signs of infection (such as sore throat that doesn't go away, fever, chills, cough). Your doctor will check your blood cell counts while you are taking this medication to decrease the risk of these side effects.

Zidovudine may also cause muscle problems. Get medical help right away if you develop signs of muscle problems (such as wasting or decrease in muscle size, weight loss, muscle weakness/pain/tenderness).

Rarely, lamivudine and zidovudine have caused severe (sometimes fatal) liver problems and a certain metabolic problem (lactic acidosis). Get medical help right away if you develop symptoms of liver problems (such as nausea that doesn't stop, vomiting, stomach/abdominal pain, pale stools, dark urine, yellowing eyes/skin, unusual tiredness), or of lactic acidosis (such as stomach discomfort, nausea, vomiting, fast/difficult breathing, drowsiness, muscle pain, weakness, cold skin). These serious side effects may occur more often in women and obese patients.

If you have hepatitis B infection and HIV, you may have a serious worsening of hepatitis symptoms if you stop taking lamivudine. Talk with your doctor before stopping this medication. Your doctor will monitor liver tests for several months after you stop lamivudine. Tell your doctor right away if you develop symptoms of worsening liver problems.