 Potential side effects include increased body temperature, increased blood pressure, sweating, increased heart rate, nausea, and upset stomach.Other side effects can include aggression, pounding heart, restlessness, fever, feeling like fainting, hallucinations, muscle twitches or spasms, abnormal behavior, severe headache, bruising easily, shortness of breath, blurred vision, seizures, ringing in the ears, chest pain, confusion, loss of appetite, weight loss, vomiting, insomnia, mild skin rash, nervousness, cold feeling in the feet or hands, tingling or numbness in the feet or hands, and difficulty staying asleep.Individuals who are on prescription medication or who suffer from various medical conditions are recommended to consult a medical care provider before consuming ExtenZe.