I just had my twice-a-year ironinfusion (jokingly refer to as my refueling) using Dextran today. They first give you a small amount to see if there is an allergic reaction. If you are going to have a severe reaction, you will have a mild case of it then. My doctor also gives me an IV with a steriod and antihistamine to help with possible sideeffects allergic reactions. This time I was given an tylenol and Zantac too -- first time for those.
I do not react to the test dose ofiron. I have a slight burning and numbness with the antihistamine/steroid, which doesn't make sense, but it is not too bad and goes away when they are done. The weird thing is I get a mild case of hives about 2 days after the ironinfusion. I just take benadryl when I start feeling itchy. The hives only last a day or two and are relatively mild.
Everyone reacts differently and there are sideeffects and risks with nearly everything you do. If they test you for the allergic reaction first before administering the larger dose, then I would certainly go with the Dextran. If you have a reaction, then you can fall back on the other form ofiron.