This medication can be responsible for both milder and more severe side effects. The most common mild reactions include upset stomach, heartburn, diarrhea, excessive gas or bloating, constipation, headaches, increased nervousness, itching, skin rashes, vision impairment, dizziness, or a ringing sound in the ears. Serious side effects should be reported to a physician and may include the following signs: chest pain, speech troubles, abrupt change in body weight, jaundice, severe skin rashes, chills, fevers, photo sensitivity, purple skin spotting, seizures, numbness, darkened urination, a loss of appetite, or the vomiting with the appearance of ground coffee.