Typical dose
For iron deficiency anemia in adults: 325 mg fer...
Oral
Oral safety: moderate
About this supplement
Ferrous sulfate is an inorganic salt of iron in the +2 oxidation state (Fe²⁺) and sulfate. It is one of the most common and cost-effective forms of iron used in dietary supplements and fortification. As a heptahydrate (FeSO₄·7H₂O), it appears as blue-green crystals, while the dried (anhydrous) form is a white to yellowish powder. It is highly bioavailable compared to non-heme iron from plant sources but less so than some chelated forms like ferrous bisglycinate. It is primarily used to treat and prevent iron deficiency anemia by replenishing iron stores for hemoglobin synthesis and other essential iron-dependent enzymes. It can cause significant gastrointestinal side effects (e.g., constipation, nausea) due to the generation of free radicals in the gut.
How much to take
- Typical amount
- For iron deficiency anemia in adults: 325 mg ferrous sulfate (providing ~65 mg elemental iron) taken 1-3 times daily. Prophylactic doses are lower, e.g., 300-325 mg once daily.
- Suggested range
- 30-200 mg elemental iron daily (dose depends on severity of deficiency, age, and gender). Typical supplement provides 65 mg elemental iron per 325 mg ferrous sulfate.
Potential benefits
Benefits linked to this supplement form:
Things to watch for
Possible side effects linked to this form:
Health goals
Needs and goals this form may help with:
Other forms of Iron
Compare absorption and active amounts with sibling forms:
Ferrous Bisglycinate (Iron Bisglycinate)
Highly bioavailable, gentle-on-the-stomach iron supplement.
Ferrous Fumarate
Iron supplement for anemia prevention and treatment
Heme Iron Polypeptide
Heme Iron Polypeptide (HIP)
Gentle, high-absorption iron with minimal GI upset. Often derived from porcine s...
Iron alpha-ketoglutarate
Iron Amino Acid Chelate
Highly bioavailable, gentle iron form.
Iron ascorbate
Iron Bile salt
Iron Bile salt (unspecified)
Iron Fructo-Oligosaccharides
Iron oxide
Iron picolinate
Iron pyrite
Polysaccharide-Iron Complex
Iron supplement with improved gastrointestinal tolerance.
Technical details ▼
Chemical ID (CAS)
7720-78-7 (anhydrous); 7782-63-0 (heptahydrate)
Formula
FeSO₄ (anhydrous); FeSO₄·7H₂O (heptahydrate)
Physical properties
Heptahydrate form: blue-green monoclinic crystals, efflorescent in dry air. Odorless. Soluble in water, insoluble in ethanol. Anhydrous form: white to yellowish powder. Aqueous solutions are acidic and oxidize in air, turning brown as Fe²⁺ oxidizes to Fe³⁺.
How it’s made
Primarily produced synthetically by dissolving iron in dilute sulfuric acid: Fe + H₂SO₄ → FeSO₄ + H₂. It is also a by-product of the steel pickling process, where iron oxides are removed from steel sheets with sulfuric acid, producing 'pickling liquor' which is processed to recover ferrous sulfate.