Levetiracetam is, in general, well tolerated[5] but may cause drowsiness, weakness, unsteady walking, coordination problems, headache, pain, forgetfulness, anxiety, irritability or hostility, dizziness, moodiness, nervousness, loss of appetite, vomiting, diarrhea, constipation, and changes in skin color.
Some serious side effects can be depression, hallucinating (hearing voices or seeing visions that do not exist), suicidal thoughts, seizures that are worse or different, fever, sore throat, and other signs of infection, double vision, itching, rash, swelling of the face. A study published in 2005 suggests that the addition of pyridoxine (vitamin B6) may curtail some of the psychiatric symptoms.[6]