ZYVOX may cause lactic acidosis (the build up of lactic acid in the body). Lactic acidosis can start slowly and gradually get worse. Symptoms include unusual muscle pain and weakness, trouble breathing, fast or uneven heart rate, nausea, vomiting, stomach pain, and numbness or cold feeling in your arms or legs. Contact your doctor at once if you have any of these symptoms, even if they are only mild. Early signs of lactic acidosis generally get worse over time and this condition can be fatal. Do not use ZYVOX if you are allergic to linezolid.

Before taking ZYVOX, tell your doctor if you are allergic to any drugs, or if you have:

*high blood pressure;
*epilepsy or other seizure disorder;
*a thyroid or adrenal gland disorder;
* kidney disease;
* liver disease; or
*bone marrow suppression or a weak immune system.

If you have any of these conditions, you may not be able to use ZYVOX, or you may need dosage adjustments or special tests during treatment.
FDA pregnancy category C. ZYVOX may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether ZYVOX passes into breast milk or if it could harm a nursing baby. Do not use ZYVOX without telling your doctor if you are breast-feeding a baby.

The oral suspension (liquid) form of ZYVOX may contain phenylalanine. Talk to your doctor before using this form of ZYVOX if you have phenylketonuria (PKU).