Hi, Considered to be a safe procedure for the treatment of varicose veins, the common side effects of sclerotherapy include bruising, raised red areas, darkened skin in the form of lines or multiple tiny red blood vessels. Although less common, based on the history you seem to have developed air bubbles in your blood stream resulting in headache, nausea and dizziness. Consult your doctor for further evaluation and appropriate treatment. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Mohammed Taher Ali, General & Family Physician