According to YohimbeGuide.Com: "Yohimbe is safe when taken in proper doses and while consulting a physician. However, Yohimbe can have serious side effects. Studies show that Yohimbe should not be taken by anyone who suffers from low blood pressure, diabetes, heart disease, liver disease or kidney disease. Yohimbe can be quite toxic and its recommended doses are very close to the dose that can be toxic. Therefore, it is important to follow directed doses carefully. Signs on an overdose include weakness, nervousness, fatigue and stomach disorders. A Yohimbe overdose can result in death. Side effects may include irritability, headache, nausea, skin flushing, sweating, dizziness, frequent urination, water retention, rise in body temperature, and hyperactivity."
I've answered my own question here. Thanks for all your input!