All medication has side effects which may vary from serious to mild. Patients should remember that their healthcare professional has prescribed ACIPHEX because they feel the benefits of taking this medication outweigh the risk of side effects. Contact your healthcare professional immediately if you have serious side effects, including: Dizziness or confusion, Fast or uneven heart rate, Jerking muscle movements, Feelings of jitteriness, Muscle cramps, weakness or limp feeling, Cough or choking feeling, Seizure or convulsions Severe headache, Upset stomach or diarrhea, Insomnia, Nervousness, Rash or itchy skin This is not a complete list of possible side effects. If you notice other effects, contact your healthcare professional immediately.