Ferrous Sulfate
The traditional, inexpensive, and most-studied iron supplement. It works well but frequently causes constipation, nausea, or stomach upset, which is why gentler forms or alternate-day dosing are often suggested.
Best for
Standard, low-cost repletion
Absorption
Moderate
Tolerability
Commonly causes GI upset
Typical timing
With vitamin C; away from calcium, coffee, and tea
How to take Ferrous Sulfate
A typical dose of Iron: Only when deficient; commonly 18–65 mg elemental iron. Best timing: With vitamin C; away from calcium, coffee, and tea. The form you choose mainly affects absorption and how easily it sits with your stomach, not the overall dose.
Where to buy Ferrous Sulfate
Choose a third-party-tested brand; the label should name this form explicitly.
Some links below are affiliate links: if you buy through them we may earn a small commission at no extra cost to you. It never changes our ratings or evidence grades.