Yes, Ferosul 325 is the same as ferrous sulfate 325 mg—they are equivalent formulations containing the same active ingredient.
Ferosul is simply a brand name for ferrous sulfate, and "325" refers to 325 mg of the ferrous sulfate compound itself, not the elemental iron content. This is a critical distinction that causes frequent confusion in clinical practice.
Understanding the Formulation
According to FDA drug labeling, Ferosul 325 mg contains 325 mg of dried ferrous sulfate as its active ingredient 1. Standard ferrous sulfate 325 mg tablets (also listed as 324 mg in some formulations) contain approximately 65 mg of elemental iron 2. This means:
- Total compound: 325 mg ferrous sulfate
- Elemental iron: ~65 mg (approximately 20% of the total compound weight)
The British Society of Gastroenterology guidelines confirm this standard conversion, noting that ferrous sulfate tablets at 200 mg contain 65 mg elemental iron, and modified-release preparations at 325 mg contain 105 mg elemental iron 3.
Clinical Implications for Prescribing
When prescribing or dispensing, Ferosul 325 and ferrous sulfate 325 mg are interchangeable and will deliver the same therapeutic dose. The AGA 2024 guidelines recommend ferrous iron salts (including ferrous sulfate) as a reasonable first-line choice because they are often the least expensive, with no substantial evidence that any one oral iron product is superior in effectiveness or tolerance 4.
Key Dosing Considerations:
- Standard dosing: 50-100 mg elemental iron once daily is recommended 4, 3
- One 325 mg ferrous sulfate tablet provides ~65 mg elemental iron, which falls within this therapeutic range
- Once-daily dosing is preferred because hepcidin levels increase for up to 48 hours after iron intake, blocking further absorption and increasing side effects without improving efficacy 4
Common Prescribing Pitfall
The most frequent error is confusing the total ferrous sulfate dose (325 mg) with the elemental iron content (~65 mg). Always verify which measurement is being referenced when communicating with patients and other providers, as this confusion can lead to under- or over-dosing.