See also the Warning section. Nausea, vomiting, dizziness, drowsiness, or unsteadiness may occur as your body adjusts to this medication. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. An empty tablet shell may appear in your stool, but it is harmless. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor immediately if any of these unlikely but serious side effects occur: swelling of the ankles/feet, fatigue, fast/slow/irregular heartbeat, persistent or severe headache, fainting, trouble urinating, change in the amount of urine, decreased sexual ability, unusual eye movements (nystagmus), vision changes, hearing problems, pain/redness/swelling of the arms or legs, numbness/tingling of the hands/feet, sun sensitivity, joint pain, hair loss. A small number of people who take anticonvulsants for any condition (such as seizure, bipolar disorder, pain) may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your doctor immediately if you or your family/caregiver notice any unusual/sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts/attempts, thoughts about harming yourself. Tell your doctor immediately if any of these rare but very serious side effects occur: persistent nausea or vomiting, severe stomach/abdominal pain, yellowing eyes and skin, dark urine, swollen glands, persistent mouth sores. Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, trouble breathing. A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.