Ferrous Sulfate 325 mg Daily for 12 Weeks with Vitamin C
Yes, ferrous sulfate 325 mg daily for 12 weeks is appropriate, and you should add vitamin C to improve iron absorption. 1
Dosing Regimen
The 2024 AGA guidelines explicitly recommend ferrous sulfate as the preferred oral iron formulation because it is the least expensive option with no proven advantages of other formulations 1. Your dose of 325 mg ferrous sulfate (containing 65 mg elemental iron) 2 taken once daily aligns with current best practices.
The guidelines clearly state: "Add vitamin C to oral iron supplementation to improve absorption" 1. The evidence supports using 500 mg of vitamin C with your iron dose to maximize absorption, even if taken with food 1. However, 80 mg of vitamin C also provides significant benefit, increasing iron absorption by 30% 3.
Optimal Timing and Administration
For maximum absorption:
- Take iron in the morning on an empty stomach - afternoon dosing results in 37% lower absorption due to circadian increases in hepcidin 3
- Take with vitamin C (80-500 mg) - either as a tablet or with orange/citrus juice 4, 3
- Avoid coffee, tea, or food within 1 hour - coffee decreases absorption by 54%, and breakfast with coffee decreases it by 66% even with vitamin C present 3
- Take with a full glass of water and remain upright for 30-60 minutes to prevent pill esophagitis 4
Duration and Monitoring
The 12-week duration is reasonable. You should expect:
- Hemoglobin increase of ≥1 g/dL within 2 weeks if treatment is working 1
- Ferritin should increase within 1 month 1
If these targets aren't met, consider non-adherence, malabsorption, or ongoing blood loss, and intravenous iron may be needed 1.
Important Caveats
Consider every-other-day dosing if you experience gastrointestinal side effects (constipation 12%, diarrhea 8%, nausea 11%) 1. The guidelines note that alternate-day dosing may be better tolerated with similar or equal iron absorption rates 1. This is because oral iron increases hepcidin for 24-48 hours, blocking further absorption 1, 5.
Evidence Nuance on Vitamin C
While the 2024 AGA guidelines recommend adding vitamin C 1, the text acknowledges that "evidence supporting vitamin C administration to improve iron absorption is mixed" 1. Recent meta-analyses show only small increases in hemoglobin (0.14 g/dL) that may not be clinically significant 6. However, given the guideline's explicit recommendation, low cost, and safety of vitamin C, adding it is justified - particularly since isotope studies demonstrate clear absorption benefits when taken correctly 3.
The key is taking vitamin C with iron on an empty stomach in the morning - this is when the benefit is most pronounced 3.