I responded to your PM with info I found on Enfamil's site - yes, the regular Poly-Vi-Sol does contain "ferrous sulfate (as a stabilizer for vitamin B12)", and it's the B12 that you want and the Poly-Vi-Sol without iron does not contain B12 so that's one of the main reasons people say get the one without iron - also the other has more iron. Here's the info from their site;
"Composition
Enfamil Poly-Vi-Sol Drops
Ingredients: Glycerin, water, ascorbic acid, polysorbate 80, vitamin E succinate, niacinamide, ferrous sulfate (as a stabilizer for vitamin B12), natural and artificial flavor, caramel color, vitamin A palmitate, thiamin hydrochloride, riboflavin-5-phosphate sodium, vitamin B6 hydrochloride, vitamin D3, vitamin B12.
Enfamil Poly-Vi-Sol with Iron Drops
Ingredients: Glycerin, water, ascorbic acid, ferrous sulfate, vitamin E succinate, niacinamide, natural and artificial flavor, caramel color, polysorbate 80, vitamin A palmitate, thiamin hydrochloride, riboflavin-5-phosphate sodium, vitamin B6 hydrochloride, vitamin D3."
I went back and read several threads you have started about your sick chicks. It will be helpful to all those trying to help if you keep updates in one thread. I saw you have chicks pooping blood in one thread and another thread about chicks starting to get stiff legs and walking only on their toes. Now they are having seizures and dying. It is NOT the Poly-Vi-Sol, unfortunately, it sounds like something much more serious going on. Separate any and all sick chicks. Keep them away from all other chicks and the rest of the flock. Keep them under a heat lamp. If you have not already given Sulmet, do so for one week - but I think your other thread mentioned you have already done so. It could be the chick that had the seizure was just too far gone with Cocci but it could be there is something much more serious happening. Keep them separated, warm and give them the Poly-Vi-Sol - it can really help any weak immune system. Only time will tell at this point but please try and consolidate all threads so everyone will have all information at hand to be able to help.
So sorry you are having these issues.