I am iron deficient for the second time in the last couple of years. I am on four ferrous sulphate tablets a day for a couple of weeks than I'm to drop to three a day. Last year it took me 2-3 months on 3 ferrous sulphate a day to get my ferritin up to 50. I did get it up to 35 after 6 weeks though. My doctor said one a day is not enough to raise ferritin. One a day can be used as a maintenance/preventative dose but not to treat it when you are actually deficient. My tablets contain 200mg ferrous sulphate which is 65mg elemental iron a day. Most people need 200mg elemental iron a day which would mean three tablets.
Its best to take it two hours after and one hour before food with orange juice.