Upon first use of the drug, some patients experience restlessness or nausea. As the patient's body receives regular doses of the drug, these problems will disappear. Other side effects that may be present are the following: convulsions, arrhythmia, increased urination, headaches, insomnia, twitching, seizures, vomiting, diarrhea, increased excitement, loss of hair, heart palpitations, irritability, skin rashes, or tremors. If any of these side effects are exhibited, a patient should contact their doctor as the dosage level may be too high.