Nausea, vomiting, stomach cramps, diarrhea, loss of appetite, headache, sun sensitivity may occur. If any of these effects continue or become bothersome, inform your doctor. This medication causes urine and possibly stools to turn orange-red in color. Do not be alarmed. This effect is temporary and will disappear when the medication is stopped. Rarely, this medication can cause serious, even fatal, side effects such as a severe peeling skin rash known as Stevens- Johnson syndrome, blood disorders (e.g., agranulocytosis, aplastic anemia), or liver damage. Seek immediate medical attention if you develop any of the following symptoms: skin rash or blisters, unusual fatigue, persistent sore throat or fever, yellowing eyes or skin, dark urine, abdominal pain. In the unlikely event you have an allergic reaction to this drug, seek immediate medical attention. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.