Two forms of the same mineral, for people a doctor has already told to supplement
Verdict
Do not start iron on your own. Iron is one of the few supplements where taking it without needing it causes real harm, because the body has no efficient way to excrete the excess, and some people have conditions that make iron overload dangerous. This page is for people whose doctor has already told them to supplement. Among those, ferrous bisglycinate, sold as gentle iron, is far better tolerated and causes less constipation and nausea. Ferrous sulfate is cheaper and delivers more elemental iron per tablet.
Iron comes up constantly in plasma donation discussion because centres check hematocrit or hemoglobin at every visit and a low reading means a deferral. It does not follow that a supplement is the answer, and self-prescribing iron is a genuinely bad idea.
Under $25
Check Nature's Bounty Gentle Iron 28 mg, 90 Count PriceUnder $25
Check Nature Made Iron 65 mg Ferrous Sulfate, 180 Count Price| Nature's Bounty Gentle Iron 28 mg, 90 Count | Nature Made Iron 65 mg Ferrous Sulfate, 180 Count | |
|---|---|---|
| Form | Ferrous bisglycinate | Ferrous sulfate |
| Elemental iron per tablet | Lower | Higher |
| Constipation and nausea | Less common | Common |
| Cost per dose | Higher | Lowest |
| Take with vitamin C | Helps absorption | Helps absorption |
| Take without medical advice | No | No |
If your doctor has recommended iron and a standard tablet has made you nauseated or constipated, ferrous bisglycinate is the form most people switch to and tolerate. It delivers less elemental iron per tablet, so the dose and the schedule are things to confirm with whoever prescribed it rather than to work out from the label. Take it as directed, away from tea, coffee, dairy and calcium supplements, all of which reduce absorption.
Check Nature's Bounty Gentle Iron 28 mg, 90 Count on Amazon
Ferrous sulfate is the cheapest and most studied form and delivers the most elemental iron per tablet, which is why it is the usual first choice clinically. It is also the form most likely to cause stomach upset and constipation. Some people tolerate it better taken with food or on alternate days, and dosing schedules are something your doctor may adjust. Keep all iron products well away from children, since iron overdose is a leading cause of poisoning deaths in young children.
Check Nature Made Iron 65 mg Ferrous Sulfate, 180 Count on Amazon
Excess iron is stored rather than excreted, and long-term overload damages the liver, heart and other organs. Some people carry hereditary haemochromatosis and have no idea until iron accumulates. That is why the honest advice on iron is the same everywhere: get a blood test and take it only if a clinician says to, at the dose and duration they set. A low hematocrit reading at a plasma centre is information to take to your own doctor, because it can have causes that a supplement will not fix and should not mask. The centre staff decide your eligibility on the day; your doctor decides what you should be taking. This site tracks plasma pay rates and does not give medical advice.
For the slow release option specifically, the Slow Fe iron supplement review covers tolerance, storage safety around children, and why iron is a supplement to take only on medical advice.
Only if a clinician has assessed them and said so. Plasma donation returns red cells to the donor, so it does not deplete iron the way whole blood donation does, and taking iron you do not need is harmful rather than neutral. If a centre defers you for a low hematocrit reading, that is a reason to see your own doctor, not a reason to start a supplement.
Labels often show both, and they are not the same number. A 325 mg ferrous sulfate tablet contains about 65 mg of elemental iron, and elemental iron is the figure that matters for dosing. Comparing products on the larger number is a common way to take far more or far less than intended, which is another reason to have the dose set by a clinician.
It improves absorption of non-heme iron, which is the form in supplements and plant foods, and it is a common instruction to take iron with a source of vitamin C. Tea, coffee, dairy and calcium supplements reduce absorption and are usually kept separate from the dose. Follow the specific instructions you were given rather than a general rule.
Centres check hematocrit or hemoglobin at every visit as part of the FDA-required screening, and a reading below their threshold means no donation that day. The causes range from being dehydrated on the morning to conditions that need investigating. Ask the centre what the number was, and take a persistent low reading to your own doctor rather than trying to correct it yourself.
Comparison based on published manufacturer specifications and the general consensus of owner reports. We have not tested these units side by side. Confirm current prices and specifications before buying. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.