The side effects of Nugenix are many and varied. Many people will experience headaches, mild to moderate dizziness, nausea or diarrhea while taking this medication. There is a risk that you may develop an irregular heartbeat if it occurs when your heart rate is low during sleep (which tends to happen often with those who exercise excessively) which can be dangerous for those without access to emergency care. Other possible side-effects include weight gain and insomnia