This medicine could cause irreversible damage to the retina of the eye if taken in higher doses or over a long period of time. If you see flashes in your vision or trouble focusing or notice swelling in your eyes, stop using this drug and contact your doctor immediately. Some serious side effects of this drug are: Seizure (convulsions), Pale skin, easy bleeding, or bruising, Muscle weakness, twitching, Light sensitivity, blurred vision, Loss of coordination or balance, Confusion, unusual behavior, or thoughts Some of the less serious side effects are: Weight loss, loss of appetite, Itching or skin rash, Headache, spinning sensation, ringing in your ears, Mood swings, feeling irritable or nervous, Hair loss, Vomiting, stomach pain, nausea