Is it possible that I will throw up after donating blood?

Yes, feeling dizzy and nauseaus after donating blood is normal. Most centres have juice and cookie stations for after a person has finished donating blood, you should go there, have some juice and cookies and wait till the feeling pes. If you do get sick, don't worry, your not the first and won't be the last. If you are worried, mention it to the nurse that is facilitating your donation and she will keep a vigilant eye on you. Also you could ask for the blood to be removed at a slower pace, which should help lower the dizziness and nausea.