Allergic reactions, dark yellow or brown urine, decreased urination, difficulty passing urine, fainting spells, dizziness, lightheadedness, fever, irregular heartbeat, chest pain, palpitations, muscle pain, tenderness, cramps, weakness, redness, blistering, peeling, loosening of the skin, including inside the mouth, skin rash, swelling of legs or ankles, unusual tiredness or weakness, yellowing of the skin or eyes, diarrhea, drowsiness, facial flushing, gas, headache, joint pain, nausea, vomiting, stomach upset or pain, tiredness, weakness & fatigue.