Thanks for contacting HCM with your health care concerns You are concerned about passing out with vomiting. This is actually a very common condition and it is called vasovagal response. When you become nauseous your bodies nervous system overacts and drops your blood pressure. There is nothing you can do other than lay down and wait for the low blood pressure to resolve. When you are nauseous and vomiting it is very important that you prevent dehydration which will compound your syncope. Be sure to stay well hydrated as the best you can I hope this answers your question. Please contact HCM again with your health care concerns and questions