How long till iron starts to work?

[BrittaPerry]

Have been prescribed an iron liquid three times a day. I am just so, so tired. How long till it will start to work!

With luck, you should start to notice an improvement in a couple of days, but it'll be more like a couple of weeks before you get the full effect - your body is replacing red blood cells all the time, so it will be swapping the low-iron ones you are running with now for ones with plenty of iron. But it's something like 3 weeks IIRC for all your red cells to be replaced, so till then you'll be working on a mix of better and less-irony ones.

Thanks :-). I was worried it would be months!