This medicine is an acyclic nucleotide analog used to treat a chronic viral infection of the liver (hepatitis B). It works by slowing the growth of the virus. It is not a cure for hepatitis B.
Side effects that may occur while taking this medicine include weakness, headache, fever, increased cough, nausea, vomiting, diarrhea, gas, sore throat, or stomach upset. If they continue or are bothersome, check with your doctor. Contact your doctor immediately if you experience unusual weakness or fatigue, dark urine, yellowing of the skin or eyes, light-colored stools, loss of appetite, abdominal or stomach pain with or without nausea or vomiting, drowsiness, muscle aches or weakness, dizziness or lightheadedness, coldness (especially in the arms or legs), trouble breathing (such as rapid breathing or very shallow breathing), fast or irregular heartbeat, or a change in the amount of urine you produce. An allergic reaction to this medicine is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include rash, itching, swelling, dizziness, or trouble breathing. If you notice other effects not listed above, contact your doctor, nurse, or pharmacist.