WOW, i have never heard of an iron infusion taking 8 hours. I would go stir crazy.
Yes, iron infusions can have side effects and the benefits should out weigh the risk but, i swear by them. It only takes me about 3 hours. I love them. After getting enough to get my iron and Hgb levels back where they should be I feel so much better. I am able to walk without almost fainting, it decreases my heart rate and increases my blood pressure. Which are all great things for me. Not for everyone though.
I would talk to your doctor and get all the info you can. Becareful about doing random searches on the internet as you can get misinformation which would cause more panic and would be more harmful to you. A board like this is great though, where you have people who are actually in similar situation and have correct data to give you.
Good luck and let us know what happens....