I would definitely start taking an iron tablet.

I am having to take 2 tablets a day as my iron levels were extremely low, if they're still as low at my next appointment I will need to have an iron transfusion.

I've had a little trouble with constipation, but that's more likely due to the fact that I need 2 tablets a day, but I have been able to combat the problem by taking some fibre tablets too and all is good