Best 7 Iron Supplements for Low Ferritin (2026): What Actually Raises Ferritin

At a Glance

• Best Overall Nature Made Iron 65 mg – USP Verified ferrous sulfate, the form doctors prescribe first, for about 4 cents a tablet.Review ↓
• Best Third-Party Certified Thorne Iron Bisglycinate – NSF certified, 25 mg of gentle Ferrochel iron.Review ↓
• Best Budget Gentle Iron Nutricost Iron Bisglycinate – the same Ferrochel form for about 8 cents a capsule.Review ↓
• Best Gentle on the Stomach Solgar Gentle Iron – 25 mg bisglycinate with a short, clean ingredient list.Review ↓

The Short Answer: Ferritin is your stored iron, and the way to raise it is to take enough elemental iron and absorb it well. Nature Made Iron 65 mg is our top pick because it delivers the 60–65 mg dose used in absorption trials, is USP Verified and costs almost nothing. If ferrous sulfate upsets your stomach, switch to a bisglycinate such as Thorne Iron Bisglycinate or the lower-cost Nutricost Iron Bisglycinate.

On this page

1. Do You Actually Need an Iron Supplement for Low Ferritin?
2. Find Your Match
3. Iron Supplements for Low Ferritin Compared
4. The 7 Best Iron Supplements for Low Ferritin, Reviewed
5. What About “Ferritin Supplements”?
6. Products We Didn’t Recommend
7. Evidence Scorecard
8. How to Take Iron for Low Ferritin
9. What to Expect and When
10. Safety, Side Effects & Drug Interactions
11. Food First: Where Else to Get Iron
12. How to Choose an Iron Supplement for Low Ferritin
13. Frequently Asked Questions
14. Final Verdict

Many people search for a “ferritin supplement,” but you don’t need to swallow ferritin to raise ferritin. Any well-absorbed iron refills your stores, and your body makes ferritin to hold it.

We compared 16 iron and ferritin labels on iron form, elemental dose, purity, additives and value, and checked sellers and certifications. Every product is ranked by its BFN Score, a relative score within this guide. See our review process for how we score.

Do You Actually Need an Iron Supplement for Low Ferritin?

Only if a blood test shows low ferritin. Ferritin reflects how much iron your body has stored, and it often drops before hemoglobin does, so you can be iron deficient without being anemic. The 2026 ASH guideline treats ferritin of 30 ng/mL or less as iron deficiency in adults without inflammation, and up to 50 ng/mL in people with symptoms or ongoing risk factors¹. Learn more in our guides to ferritin vs. iron vs. hemoglobin and normal ferritin levels by age and gender.

Low ferritin is common in women with heavy periods, pregnant women, vegetarians, frequent blood donors and endurance athletes. It can also signal blood loss or poor absorption, such as from celiac disease, so your doctor should look for the cause rather than just treating the number. See why ferritin can be low with normal hemoglobin.

Who Should Skip It

• People who haven’t had their iron checked: excess iron can’t be excreted easily and builds up over time².
• People with hemochromatosis or other iron-overload conditions.
• People with high ferritin from inflammation, liver disease or chronic illness, unless their doctor recommends iron.
• Men and postmenopausal women with unexplained low iron: this needs a medical work-up for hidden blood loss first.
• Households with young children, unless the bottle is locked away: accidental iron overdose is dangerous for children².

Nutritionist tip: get your ferritin retested about 8 to 12 weeks after you start. That is the only way to know whether your supplement and dose are working.

Find Your Match

If you…	Consider	Why
Want the evidence-based standard at the lowest cost	Nature Made Iron 65 mg	65 mg ferrous sulfate, USP Verified
Want independent certification	Thorne Iron Bisglycinate	NSF certified Ferrochel iron
Want gentle iron on a budget	Nutricost Iron Bisglycinate	25 mg Ferrochel, about 8 cents a capsule
Get constipation or nausea from iron	Solgar Gentle Iron	Bisglycinate, minimal additives
Want vitamin C in the same capsule	Pure Encapsulations OptiFerin-C	28 mg iron plus 100 mg vitamin C
Need a lower maintenance dose after ferritin recovers	Pink Stork Iron	18 mg iron, 100% DV
Can’t swallow pills	MaryRuth’s Liquid Iron	Sugar-free liquid Ferrochel
Have hemochromatosis or haven’t been tested	Talk to your doctor first	Iron can build up to harmful levels

Iron Supplements for Low Ferritin Compared

Scroll sideways to see every column →

#	Product	Form	Dose per Serving	% DV	Servings	Daily Pills	Purity Testing	Additives	Diet	Cost
1	Nature Made Iron 65 mg	Tablet	65 mg iron (ferrous sulfate)	361%	180	1	USP Verified	Clean	No synthetic dyes	$$$
2	Thorne Iron Bisglycinate	Capsule	25 mg iron (bisglycinate)	139%	60	1–2	NSF certified	Clean	Gluten-free	$$$
3	Nutricost Iron Bisglycinate	Capsule	25 mg iron (bisglycinate)	139%	120	1–2	Third-party tested (lab not named)	Clean	Gluten-free	$$$
4	Solgar Gentle Iron	Capsule	25 mg iron (bisglycinate)	139%	180	1–2	Not stated	Clean	Vegan, gluten-free	$$$
5	Pure Encapsulations OptiFerin-C	Capsule	28 mg iron (bisglycinate), 100 mg vitamin C	156%	60	1–2	Not stated	Clean	Vegan	$$$
6	Pink Stork Iron	Capsule	18 mg iron (bisglycinate), 50 mg vitamin C	100%	60	1	Not stated	Clean	Vegan	$$$
7	MaryRuth’s Liquid Iron	Liquid	18 mg iron (bisglycinate) per tablespoon	100%	About 30	1 tbsp	Not stated	Note: stevia	Vegan, sugar-free	$$$

Cost tiers per serving: $ under $0.10 · $$ $0.10–$0.25 · $$$ over $0.25 (checked November 2026). % DV based on the 18 mg Daily Value for iron. MaryRuth’s dose is for adults 19–50; adults 51+ use 1 teaspoon (6 mg).

The 7 Best Iron Supplements for Low Ferritin, Reviewed

#1Best Overall

1. Nature Made Iron 65 mg

BFN Score9.6/10

$$$Budget180 servings1 tablet per serving

Strongest atEvidence fitWeakest atDose & safety

Ferrous sulfate is the iron most doctors prescribe first, and each Nature Made tablet gives 65 mg of elemental iron from 325 mg of ferrous sulfate. It is USP Verified, sold by Amazon and costs about 4 cents a tablet.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as ferrous sulfate

Dose per serving

65 mg elemental iron (1 tablet)

Dose vs. research

Within studied range; absorption trials in iron-depleted women used 60 mg³

% DV / Upper Limit

361% DV; above the 45 mg upper limit for healthy adults, which doesn’t apply to treatment under medical supervision²

Purity testing

USP Verified

Other ingredients

cellulose gel, dicalcium phosphate, croscarmellose sodium, magnesium stearate, rice starch, hypromellose, isomalt, medium-chain triglycerides, carnauba wax

Additives

Clean – no synthetic dyes

Allergens & diet

gluten-free

Safety flags

Constipation and nausea; keep away from children; separate from levothyroxine and some antibiotics²

Clinical Relevance

In iron-depleted women, a 60 mg dose taken every other day was absorbed better than the same dose every day, because a daily dose raises hepcidin, the hormone that blocks the next day’s absorption³. One 65 mg tablet every other day fits that pattern. Ferrous sulfate causes more stomach side effects than placebo⁵, so alternate days can also help tolerance.

Strengths

• USP Verified
• Matches the dose used in absorption trials
• Lowest cost in this guide

Limitations

• Most likely to cause constipation or nausea
• Above the upper limit for people who don’t need treatment
• Metallic taste for some people

Practical Details

Take one tablet every other day on an empty stomach with water or orange juice, or with a small meal if it upsets your stomach. Avoid tea, coffee and calcium for two hours around the dose.

Best For / Not For

Best foradults with confirmed low ferritin who want the standard treatment at the lowest cost.

Not forpeople who haven’t been tested, or who can’t tolerate ferrous sulfate.

Buyer Experience

Buyers say it helps with anemia, keeps their iron levels normal and leaves them feeling more active. Most find the tablets easy to swallow.

Digestion is the dividing line: some notice no stomach upset, while others report severe indigestion. Taste is also mixed.

vs. Thorne Iron Bisglycinate

Choose Nature Made for the strongest evidence and lowest cost. Choose Thorne if ferrous sulfate gives you stomach trouble.

Nutritionist’s Note

If you get constipated, try alternate days before switching products; it often helps and may improve absorption too³.

Verdict: The evidence-based standard for refilling iron stores, at the lowest price.

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#2Best Third-Party Certified

2. Thorne Iron Bisglycinate

BFN Score9.5/10

$$$Premium60 servings1 capsule per serving

Strongest atPurity & trustWeakest atValue

Thorne uses Ferrochel iron bisglycinate, a form bound to the amino acid glycine that tends to be gentler on the stomach. It is listed in NSF’s certified products database, and the ingredient list is four items long.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as Ferrochel ferrous bisglycinate chelate

Dose per serving

25 mg elemental iron (1 capsule)

Dose vs. research

Below studied range at 1 capsule; 2 capsules (50 mg) is close to trial doses³

% DV / Upper Limit

139% DV; 1 capsule is below the 45 mg upper limit²

Purity testing

NSF certified

Other ingredients

hypromellose capsule, microcrystalline cellulose, leucine, silicon dioxide

Additives

Clean

Allergens & diet

gluten-free

Safety flags

Keep away from children; separate from levothyroxine and some antibiotics²

Clinical Relevance

A meta-analysis of 17 randomized trials found that ferrous bisglycinate raised hemoglobin more than other iron salts in pregnant women and caused 64% fewer stomach side effects⁴. The data in non-pregnant adults are more limited.

Strengths

• NSF certified
• Gentle bisglycinate form
• Very short ingredient list

Limitations

• Only 60 capsules
• Two capsules needed to reach trial doses
• Sold by a third-party seller (Pattern)

Practical Details

Take one capsule daily, or two capsules every other day if your doctor wants a treatment dose. Food reduces stomach upset but also absorption.

Best For / Not For

Best forpeople who want certified quality and a gentle form.

Not forbudget buyers who need 50 mg a day.

Buyer Experience

Buyers say it works better than generic iron and helps restore their iron and ferritin levels. Many find it gentle on the stomach and easy to swallow.

Value divides opinion: some think it is well worth the price, while others find it too expensive.

vs. Nutricost Iron Bisglycinate

Both use Ferrochel at 25 mg. Choose Thorne for NSF certification; choose Nutricost for about a third of the cost per capsule.

Nutritionist’s Note

Bisglycinate is still iron: if you take 50 mg a day, you need a ferritin check to avoid overshooting.

Verdict: Certified, gentle iron for people who will pay for verified quality.

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#3Best Budget Gentle Iron

3. Nutricost Iron Bisglycinate

BFN Score9.3/10

$$$Budget120 servings1 capsule per serving

Strongest atValue & practicalityWeakest atQuality & trust

Nutricost uses the same Ferrochel bisglycinate as Thorne at 25 mg per capsule, with 120 capsules for about 8 cents each. The brand says every batch is tested by independent ISO-accredited labs and made in an NSF-registered GMP facility.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as Ferrochel ferrous bisglycinate chelate

Dose per serving

25 mg elemental iron (1 capsule)

Dose vs. research

Below studied range at 1 capsule; 2 capsules (50 mg) is close to trial doses³

% DV / Upper Limit

139% DV; 1 capsule is below the 45 mg upper limit²

Purity testing

Third-party tested by ISO-accredited labs, lab not named

Other ingredients

rice flour, hypromellose capsule, citric acid, magnesium stearate

Additives

Clean

Allergens & diet

gluten-free, non-GMO

Safety flags

Keep away from children; separate from levothyroxine and some antibiotics²

Clinical Relevance

The bisglycinate form caused fewer stomach side effects than other iron salts in randomized trials⁴. At 8 cents a capsule, taking two capsules for a treatment dose still costs less than one capsule of most premium brands.

Strengths

• Lowest-cost Ferrochel iron in this guide
• 120 capsules per bottle
• Short ingredient list

Limitations

• Testing lab not named
• No independent certification mark
• Two capsules needed to reach trial doses

Practical Details

Take one capsule a day, or two every other day if your doctor recommends a treatment dose. Take with water or a vitamin C-rich drink.

Best For / Not For

Best forbudget buyers who want a gentle form.

Not forpeople who want an NSF or USP certification mark.

Buyer Experience

Buyers say it works, is easy to swallow and absorbs well without digestive distress. Many praise its quality and call the value unbeatable.

vs. Solgar Gentle Iron

Both give 25 mg of bisglycinate at a similar cost. Choose Nutricost for the brand’s third-party testing claim; choose Solgar for a larger 180-capsule bottle.

Nutritionist’s Note

Cheap iron is only a bargain if you take it consistently, so pick the form you tolerate and set a reminder for every-other-day dosing.

Verdict: Gentle Ferrochel iron at a budget price.

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#4Best Gentle on the Stomach

4. Solgar Gentle Iron

BFN Score9.2/10

$$$Budget180 servings1 capsule per serving

Strongest atDose & safetyWeakest atQuality & trust

Solgar Gentle Iron is one of the longest-running bisglycinate products, with 25 mg of iron per capsule and only three other ingredients. It is sold by Amazon, and a bottle lasts six months.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as iron bisglycinate chelate

Dose per serving

25 mg elemental iron (1 capsule)

Dose vs. research

Below studied range at 1 capsule; 2 capsules (50 mg) is close to trial doses³

% DV / Upper Limit

139% DV; 1 capsule is below the 45 mg upper limit²

Purity testing

Not stated

Other ingredients

microcrystalline cellulose, vegetable cellulose, vegetable magnesium stearate

Additives

Clean

Allergens & diet

vegan; free of gluten, wheat, dairy and soy

Safety flags

Keep away from children; separate from levothyroxine and some antibiotics²

Clinical Relevance

Bisglycinate’s main advantage is tolerability: fewer stomach side effects than other iron salts⁴. That matters because people who stop taking iron because of constipation never refill their stores.

Strengths

• Very short ingredient list
• 180 capsules per bottle
• Sold by Amazon

Limitations

• No third-party testing claim on the listing
• Two capsules needed to reach trial doses
• No added vitamin C

Practical Details

Take one capsule a day with water, or two every other day if your doctor recommends a treatment dose.

Best For / Not For

Best forpeople who got constipated on ferrous sulfate.

Not forpeople who want a certification mark.

Buyer Experience

Buyers find it effective and gentle, with no constipation or digestive issues. Many report better blood work and hemoglobin, more energy and less fatigue.

They also find it easy to swallow and good value.

vs. Nutricost Iron Bisglycinate

Choose Solgar for a six-month bottle sold by Amazon. Choose Nutricost if you want a third-party testing claim.

Nutritionist’s Note

If you take a calcium supplement, take it at a different meal; calcium reduces iron absorption.

Verdict: A gentle, simple bisglycinate that most stomachs tolerate.

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#5Best with Vitamin C

5. Pure Encapsulations OptiFerin-C

BFN Score9.1/10

$$$Premium60 servings1 capsule per serving

Strongest atDose & safetyWeakest atQuality & trust

OptiFerin-C pairs 28 mg of iron bisglycinate with 100 mg of vitamin C, which helps the gut absorb non-heme iron². It is a small capsule with a short, hypoallergenic ingredient list.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as iron bisglycinate, vitamin C as calcium ascorbate

Dose per serving

28 mg iron, 100 mg vitamin C, 11 mg calcium (1 capsule)

Dose vs. research

Below studied range at 1 capsule; 2 capsules (56 mg) is within trial doses³

% DV / Upper Limit

156% DV iron; 1 capsule is below the 45 mg upper limit²

Purity testing

Not stated

Other ingredients

vegetarian capsule (cellulose, water), ascorbyl palmitate, cellulose

Additives

Clean

Allergens & diet

vegan

Safety flags

Keep away from children; separate from levothyroxine and some antibiotics²

Clinical Relevance

Vitamin C improves non-heme iron absorption², so a built-in dose saves you from timing iron with orange juice. The small amount of calcium in the ascorbate is unlikely to matter at 11 mg.

Strengths

• Iron and vitamin C in one capsule
• Gentle bisglycinate form
• Small capsule

Limitations

• 60 capsules only
• Higher cost per milligram of iron
• Sold by a third-party seller (Pattern)

Practical Details

Take one capsule a day, or two every other day for a treatment dose, between meals.

Best For / Not For

Best forpeople who want a single capsule with vitamin C.

Not forbudget buyers.

Buyer Experience

Buyers say it works, with one reporting a higher ferritin level, and that it is gentle without cramps or diarrhea. Many like the energy boost, the added vitamin C and the pure ingredients.

Value divides opinion: some call it great value, others find it expensive.

vs. Pink Stork Iron

Both add vitamin C. Choose OptiFerin-C for a higher iron dose for low ferritin; choose Pink Stork for a lower maintenance dose.

Nutritionist’s Note

Extra vitamin C helps, but tea and coffee within an hour of your dose can cancel much of that benefit.

Verdict: A convenient iron-plus-C capsule in a gentle form.

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#6Best Low-Dose for Women

6. Pink Stork Iron

BFN Score8.6/10

$$$Premium60 servings1 capsule per serving

Strongest atDose & safetyWeakest atEvidence fit

Pink Stork gives 18 mg of iron bisglycinate, exactly 100% of the Daily Value, plus 50 mg of vitamin C from acerola. That is a good maintenance dose once ferritin is back in range, but low for refilling depleted stores.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as iron bisglycinate, vitamin C from acerola extract

Dose per serving

18 mg iron, 50 mg vitamin C (1 capsule)

Dose vs. research

Below studied range for repletion³; matches the RDA for women 19–50²

% DV / Upper Limit

100% DV; below the 45 mg upper limit

Purity testing

Not stated

Other ingredients

acerola extract, hypromellose, microcrystalline cellulose, magnesium stearate, silicon dioxide

Additives

Clean

Allergens & diet

vegan

Safety flags

Keep away from children; ask your doctor before use in pregnancy²

Clinical Relevance

18 mg covers the daily need of a menstruating woman², but it is a third of the dose used in absorption trials in iron-depleted women³. Use it to maintain ferritin after treatment, or when your doctor recommends a lower dose.

Strengths

• Gentle bisglycinate form
• Built-in vitamin C
• Simple one-a-day dose

Limitations

• Low dose for repletion
• Highest cost per milligram among the capsules
• No third-party testing claim

Practical Details

Take one capsule daily, with or without food. Retest ferritin to confirm the lower dose keeps your levels stable.

Best For / Not For

Best forwomen maintaining ferritin after treatment.

Not forpeople with very low ferritin who need a treatment dose.

Buyer Experience

Buyers find it effective, with one reporting better hemoglobin during pregnancy. Many say it is gentle, doesn’t cause constipation and has no iron aftertaste.

They also report more energy and consider it good value, especially during pregnancy.

vs. MaryRuth’s Liquid Iron

Both give 18 mg. Choose Pink Stork for a capsule with vitamin C; choose MaryRuth’s if you can’t swallow pills.

Nutritionist’s Note

If you are pregnant, your prenatal may already contain 27 mg of iron; ask your doctor before adding more.

Verdict: A gentle maintenance iron, not a first choice for very low ferritin.

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#7Best Liquid

7. MaryRuth’s Liquid Iron

BFN Score8.2/10

$$$PremiumAbout 30 servings1 tablespoon per serving

Strongest atDose & safetyWeakest atValue

This sugar-free berry liquid gives 18 mg of Ferrochel iron per tablespoon for adults 19–50 and 6 mg per teaspoon for adults 51 and older. It is the easiest way to take iron if pills are a problem.

Check price on Amazon →

Label Reality Check

Active ingredient + form

iron as Ferrochel ferrous bisglycinate chelate

Dose per serving

18 mg iron per tablespoon (adults 19–50); 6 mg per teaspoon (adults 51+)

Dose vs. research

Below studied range for repletion³; matches the RDA for women 19–50²

% DV / Upper Limit

100% DV; below the 45 mg upper limit

Purity testing

Not stated

Other ingredients

purified water, organic vegetable glycerin, natural flavor, citric acid, organic rebaudioside A (stevia), xanthan gum

Additives

Note – stevia sweetener

Allergens & diet

vegan, sugar-free, gluten-free

Safety flags

Keep away from children; measure doses carefully²

Clinical Relevance

It uses the same Ferrochel form as the capsules in this guide, and the dose can be adjusted in small steps. At 18 mg per tablespoon, reaching a treatment dose would take several tablespoons, which makes it expensive for repletion.

Strengths

• No pills to swallow
• Sugar-free and vegan
• Easy to adjust the dose

Limitations

• Highest cost per milligram in this guide
• Low dose per serving
• About a one-month bottle for adults 19–50

Practical Details

Shake well and take one tablespoon a day (adults 19–50) or one teaspoon (51+). Store it as the label directs.

Best For / Not For

Best forpeople who can’t swallow capsules.

Not forpeople who need a high treatment dose on a budget.

Buyer Experience

Buyers find it easier than pills and say it improved their iron and energy levels without stomach upset or constipation.

Taste divides opinion: some love it, others find it sickly sweet. Opinions on value are also split.

vs. Pink Stork Iron

Same 18 mg dose. Choose MaryRuth’s to avoid pills; choose Pink Stork for a lower cost per dose.

Nutritionist’s Note

Use the measuring tool or a proper tablespoon, not a kitchen spoon; doses can vary a lot.

Verdict: The best liquid option for pill-averse adults.

SEE PRICE ON AMAZON →

What About “Ferritin Supplements”?

Products sold as “ferritin” contain iron stored inside a ferritin protein, from plants or animals. Flora Ferritin+ uses pea ferritin and gives 20 mg of iron per capsule, while Cardiovascular Research Ferritin uses bovine ferritin and gives only 5 mg. Neither puts ferritin directly into your blood; your body breaks the protein down and absorbs the iron like other iron.

So the label word “ferritin” isn’t what raises your ferritin. The amount of elemental iron you absorb is. That is why we ranked products by iron form and dose, not by the name.

Products We Didn’t Recommend

Slow Fe 45 mg. Slow-release iron is released past the upper small intestine, where iron absorption is highest. The tablets also contain talc, titanium dioxide and three synthetic dyes (Red 40, Yellow 6 and Blue 1 lakes).

Nutra Harmony Iron 65 mg. It uses a delayed-release capsule, with the same absorption concern as slow-release iron, and adds 500 mcg of folic acid.

Flora Ferritin+. Pea ferritin in a delayed-release capsule has limited human data and costs about 74 cents a day.

Cardiovascular Research Ferritin. At 5 mg of iron per capsule, it is too low to refill depleted stores.

Hemeboost Heme Iron Polypeptide. It gives 11.6 mg of iron per tablet at a high cost per milligram.

Vitanica Iron Extra. The title says iron bisglycinate, but the listed ingredients show aspartate, succinate and fumarate plus herbs, so we couldn’t confirm the formula.

Micro Ingredients Blood+ and Purity Products MyIron. Blood+ is a 14-ingredient blend rather than a focused iron product, and MyIron has very few reviews at a high price.

Evidence Scorecard

Ingredient / Form	What it’s studied for	Evidence level	Notes
Ferrous sulfate	Treating iron deficiency	Strong	First-line oral iron; more GI side effects than placebo5
Alternate-day dosing	Iron absorption	Moderate	60 mg every other day absorbed better than daily in iron-depleted women3
Ferrous bisglycinate	Hemoglobin, tolerability	Moderate	Fewer GI side effects than other iron salts; strongest data in pregnancy4
Vitamin C with iron	Non-heme iron absorption	Moderate	Enhances absorption2
Plant or animal ferritin	Raising ferritin	Limited	Few human studies; iron content varies widely

Oral iron reliably raises ferritin in people who are iron deficient. The best product is the one you can take consistently at the dose your doctor recommends, with follow-up testing.

How to Take Iron for Low Ferritin

Group	Iron RDA	Upper Limit (healthy adults)
Women 19–50	18 mg	45 mg
Men 19+ and women 51+	8 mg	45 mg
Pregnancy	27 mg	45 mg
Breastfeeding	9 mg	45 mg

Vegetarians need about 1.8 times more iron. Treatment doses above the upper limit should be used only under medical supervision. Source: NIH Office of Dietary Supplements².

• Take iron every other day if your doctor agrees; it was absorbed better than daily dosing³.
• Take it on an empty stomach or with a little food if it upsets your stomach.
• Pair it with vitamin C (orange juice or a supplement)².
• Keep tea, coffee, dairy and calcium supplements at least two hours away from your dose.
• Retest ferritin after 8 to 12 weeks.

For more on iron, see our guides to the best-tolerated iron supplements, 325 mg ferrous sulfate and what causes low ferritin.

What to Expect and When

Energy and symptoms such as hair shedding or restless legs often improve over several weeks. Ferritin rises more slowly: expect to recheck at 8 to 12 weeks, and many doctors continue iron for a few months after levels normalize to rebuild stores.

If ferritin doesn’t rise despite consistent use, ask your doctor about absorption problems, ongoing blood loss or intravenous iron.

Safety, Side Effects & Drug Interactions

Constipation, nausea, stomach pain and dark stools are the most common side effects of oral iron, especially ferrous sulfate⁵. Bisglycinate forms cause fewer stomach complaints⁴.

Medication or condition	Possible interaction	What to do
Levothyroxine	Iron reduces absorption2	Separate by 4 hours
Levodopa	Iron reduces absorption2	Ask your doctor about timing
Quinolone and tetracycline antibiotics	Iron reduces absorption	Separate by at least 2 hours
Proton pump inhibitors (omeprazole)	Lower stomach acid reduces iron absorption2	Ask your doctor; bisglycinate may help
Calcium supplements and antacids	Reduce iron absorption	Take at a different time
Hemochromatosis	Iron overload	Do not take iron
Young children in the home	Accidental overdose can be fatal2	Store bottles locked and out of reach

Food First: Where Else to Get Iron

Heme iron from red meat, poultry and fish is absorbed best. Non-heme iron comes from beans, lentils, tofu, spinach and fortified cereals, and is absorbed better with vitamin C-rich foods².

Food alone rarely corrects low ferritin quickly, but it helps maintain levels once your stores are refilled.

How to Choose an Iron Supplement for Low Ferritin

Form and Absorption

Ferrous sulfate is the proven, low-cost standard. Ferrous bisglycinate (Ferrochel) is gentler on the stomach⁴. Avoid slow- or delayed-release iron for repletion.

Dose and % DV

Check elemental iron, not the weight of the iron compound: 325 mg of ferrous sulfate gives 65 mg of iron. Trials in iron-depleted women used about 60 mg every other day³.

Purity Testing

Look for USP Verified or NSF certification. Among our picks, Nature Made and Thorne carry independent certification.

Additives and Allergens

Avoid synthetic dyes, talc and titanium dioxide when simpler options exist.

Pill Burden and Format

One 65 mg tablet or two 25 mg capsules every other day is a typical repletion routine. Liquids suit people who can’t swallow pills.

Cost per Effective Dose

Compare cost per milligram of elemental iron. Ferrous sulfate costs a fraction of a cent per milligram; liquids cost the most.

Important: These supplements are not intended to diagnose, treat, cure, or prevent any disease. Results vary by individual. If you have a health condition or take medications, check with your doctor before adding any new supplement to your routine.

Frequently Asked Questions

Final Verdict

Nature Made Iron 65 mg is our top iron supplement for low ferritin: the standard ferrous sulfate dose, USP Verified and the lowest cost.

If iron upsets your stomach, choose Thorne Iron Bisglycinate for certified quality or Nutricost Iron Bisglycinate for the same form at a budget price. For a liquid, choose MaryRuth’s Liquid Iron.

Always confirm low ferritin with a blood test first, and ask your doctor to look for the cause.

Sources & History5 sources · updated November 2, 2026

References

1. New iron deficiency guidelines raise key blood test cutoffs (ASH 2026 guideline, Blood Advances) — News-Medical, 2026
2. Iron: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
3. Iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women — Lancet Haematology, 2017
4. The effects of oral ferrous bisglycinate supplementation on hemoglobin and ferritin concentrations in adults and children: a systematic review and meta-analysis of randomized controlled trials — Nutrition Reviews, 2023
5. Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis — PLoS One, 2015

Update history

• November 2, 2026Rebuilt with BFN Score v3: compared 16 labels; new list ranked by iron form, elemental dose, purity and value; added Nature Made, Thorne, Solgar, Pure Encapsulations and MaryRuth’s; kept Nutricost and Pink Stork; removed Micro Ingredients Blood+ and Purity MyIron; added the 2026 ASH ferritin thresholds, alternate-day dosing, a section on “ferritin” supplements and an interaction table.