What is the equivalent over-the-counter (OTC) iron to ferrous sulfate 324 milligrams?

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From the Guidelines

The equivalent over-the-counter (OTC) iron supplement to prescription ferrous sulfate 324 mg is ferrous sulfate 325 mg, which provides approximately 65 mg of elemental iron per tablet, as indicated in the study by 1. This OTC option is commonly available under brand names like Feosol, Slow FE, or generic store brands labeled as ferrous sulfate. When purchasing, look specifically for products containing ferrous sulfate rather than other iron forms like ferrous gluconate or ferrous fumarate, which contain different amounts of elemental iron, as noted in the study by 1. Some key points to consider when taking these supplements include:

  • Take them with vitamin C (such as orange juice) to enhance absorption,
  • Avoid taking them with dairy products, coffee, tea, calcium supplements, or antacids, which can reduce absorption. Be aware that iron supplements commonly cause constipation, dark stools, and stomach upset, as mentioned in the study by 1. Start with one tablet daily and gradually increase as tolerated to minimize side effects. Store these supplements safely away from children, as iron overdose can be dangerous. The slight difference between 324 mg and 325 mg is negligible in terms of therapeutic effect, and according to the study by 1, ferrous sulfate is preferred as the least expensive iron formulation. Additionally, the study by 1 recommends starting with one tablet per day of ferrous sulphate, which supports the use of ferrous sulfate 325 mg as an equivalent OTC option.

From the FDA Drug Label

Each tablet contains 324mg of ferrous sulfate, equivalent to 65mg of elemental iron, To find an equivalent OTC iron to ferrous sulfate 324mg, we need to find an OTC iron supplement that contains 65mg of elemental iron.

  • The equivalent OTC iron can be in the form of different iron salts, such as ferrous gluconate, ferrous fumarate, or others, as long as it contains 65mg of elemental iron 2.

From the Research

Equivalent OTC Iron to Ferrous Sulfate 324mg

To determine the equivalent OTC iron to ferrous sulfate 324mg, we need to consider the elemental iron content in each preparation.

  • Ferrous sulfate 324mg typically contains 65mg of elemental iron 3.
  • Other oral iron preparations, such as ferrous fumarate, ferrous gluconate, and iron protein succinylate, may have different amounts of elemental iron 4, 3, 5. Some key points to consider:
  • Ferrous fumarate and ferrous gluconate may have lower elemental iron content compared to ferrous sulfate 3.
  • Iron protein succinylate may have a higher elemental iron content compared to ferrous sulfate 5.
  • Extended-release ferrous sulfate with mucoproteose may have better tolerability compared to other oral iron supplements 5.

Comparison of Oral Iron Preparations

The following oral iron preparations can be compared to ferrous sulfate 324mg:

  • Ferrous fumarate: may require a higher dose to achieve the same elemental iron content as ferrous sulfate 324mg 3.
  • Ferrous gluconate: may require a higher dose to achieve the same elemental iron content as ferrous sulfate 324mg 3.
  • Iron protein succinylate: may have a similar or higher elemental iron content compared to ferrous sulfate 324mg 5. It is essential to note that the elemental iron content and tolerability of different oral iron preparations can vary significantly 3, 5.

Key Findings

  • Ferrous sulfate 324mg contains 65mg of elemental iron 3.
  • Other oral iron preparations may have different amounts of elemental iron 4, 3, 5.
  • Extended-release ferrous sulfate with mucoproteose may have better tolerability compared to other oral iron supplements 5. When choosing an equivalent OTC iron to ferrous sulfate 324mg, it is crucial to consider the elemental iron content and tolerability of different oral iron preparations 3, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Iron deficiency anemia in patients with inflammatory bowel disease.

Clinical and experimental gastroenterology, 2013

Research

Tolerability of different oral iron supplements: a systematic review.

Current medical research and opinion, 2013

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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