Low Ferritin: Symptoms, Causes, and How to Raise It

Your blood test results are back, and your ferritin is low—but your hemoglobin is normal. What does this mean? Do you have anemia? Should you be taking iron supplements?

This guide will explain what low ferritin means, what symptoms you might experience, why ferritin can be low even when you're not anemic yet, and what to do about it.

Important: These ranges vary by lab and by individual. Some people feel symptomatic at higher levels, especially athletes or women with heavy menstrual periods.

Understanding the difference between ferritin and hemoglobin is key:

Ferritin = Iron Warehouse

• Ferritin stores iron for future use
• It's your body's iron savings account
• Low ferritin = your iron stores are running low
• You can have low ferritin before your hemoglobin drops

Hemoglobin = Iron in Use

• Hemoglobin uses iron to carry oxygen
• It's like the iron you're spending day to day
• Low hemoglobin = anemia (not enough oxygen-carrying capacity)
• Hemoglobin drops after ferritin is depleted

The progression:

1. Ferritin drops first (iron stores depleted)
2. You may have symptoms even with normal hemoglobin
3. If depletion continues, hemoglobin eventually drops (iron deficiency anemia)

This is why you can have low ferritin without anemia—and still feel terrible!

Many doctors were taught that low ferritin without anemia doesn't cause symptoms. This is wrong. Research clearly shows that low ferritin can cause significant symptoms even when hemoglobin is still normal.

Common Symptoms

The "Hidden" Nature of Low Ferritin Symptoms

The frustrating thing about low ferritin symptoms:

• They're nonspecific (could be many things)
• They develop gradually (you might not notice at first)
• They're often dismissed as "stress" or "normal fatigue"
• You might look "fine" on the outside while feeling exhausted inside

But these symptoms are real. Research confirms that low ferritin without anemia can cause:

• Reduced exercise capacity
• Fatigue that affects daily life
• Cognitive symptoms affecting work and school
• Hair loss that's distressing
• Reduced quality of life

1. Inadequate Iron Intake - MOST COMMON

Who's at risk:

• Vegetarians and vegans: Plant-based iron (non-heme) is less well absorbed
• People who avoid red meat: Red meat is the richest iron source
• Restrictive eaters: Diets that eliminate multiple food groups
• People with poor diets: High processed food, low nutrient density

How much iron do you need?

2. Menstrual Blood Loss - VERY COMMON IN WOMEN

Who's at risk:

• Women with heavy periods (menorrhagia)
• Women with long periods (more than 5-7 days)
• Women with frequent periods (short cycles)
• Women with fibroids or endometriosis

How much iron is lost?

• Average menstrual blood loss: 30-40 mL per cycle
• Heavy menstrual bleeding: 80 mL or more per cycle
• Each mL of blood contains about 0.5 mg of iron
• Heavy periods can deplete iron stores faster than diet can replenish

Signs your periods are causing iron loss:

• Changing pad/tampon every 1-2 hours
• Passing clots larger than a quarter
• Bleeding through clothes at night
• Periods lasting more than 7 days
• Fatigue that gets worse during your period

3. Pregnancy and Breastfeeding

Pregnancy:

• Blood volume increases 50%
• Baby takes iron for their own stores
• Iron needs triple during pregnancy
• Low ferritin is extremely common if not supplementing

Breastfeeding:

• Each ounce of breast milk contains iron
• Your body prioritizes baby over you
• Prolonged breastfeeding can deplete stores

4. Gastrointestinal Blood Loss

Common causes:

• Gastritis or ulcers: From H. pylori infection or NSAID use
• Colon polyps: Can bleed slowly over time
• Colorectal cancer: Significant cause in older adults
• Inflammatory bowel disease: Crohn's, ulcerative colitis
• Celiac disease: Damages intestine, causing poor iron absorption AND blood loss
• Hemorrhoids: Usually minor, but can add up
• Angiodysplasia: Abnormal blood vessels in the GI tract

Red flags for GI blood loss:

• Black, tarry stools
• Visible blood in stools
• Stomach pain (especially with NSAID use)
• Unexplained weight loss
• Family history of colon cancer or polyps

Important: In men and postmenopausal women, low ferritin should ALWAYS prompt investigation for GI bleeding. It's not normal in these groups.

5. Poor Iron Absorption

Even with adequate intake, your body might not absorb iron well:

Conditions that impair absorption:

• Celiac disease: Damages the part of intestine that absorbs iron
• Gastric bypass surgery: Bypasses the stomach where iron absorption happens
• Atrophic gastritis: Low stomach acid reduces iron absorption
• H. pylori infection: Can affect absorption
• Chronic proton pump inhibitor (PPI) use: Reduces stomach acid needed for iron absorption

6. Frequent Blood Donation

Regular blood donation:

• Each donation removes about 250 mg of iron
• Takes 3-6 months to replenish iron stores
• Frequent donors (especially women) often have low ferritin

Good news: Blood centers usually test ferritin and will defer you if it's too low.

7. Intense Physical Activity

Athletes are at higher risk for low ferritin:

• Footstrike hemolysis (red blood cells break down from foot impact)
• Iron loss through sweat and urine
• GI blood loss from intense exercise
• Increased iron needs for muscle function

Who's most at risk:

• Endurance athletes (runners, triathletes)
• Female athletes (especially with menstrual cycles)
• Vegetarian athletes

Blood Tests

The key test: Ferritin. This is the most sensitive test for iron deficiency, showing up before anemia develops.

Functional Iron Deficiency

Some people have:

• Normal or low-normal ferritin (30-50 ng/mL)
• But symptoms of iron deficiency
• And they improve with iron supplements

This is called "functional iron deficiency"—you have enough iron for basic needs, but not enough for optimal function.

Oral Iron Supplements

Types:

Dosing:

• Typical: 325 mg ferrous sulfate (65 mg elemental iron) 2-3 times daily
• Taking with vitamin C improves absorption
• Avoid calcium, antacids, and tea/coffee within 2 hours of iron

Side effects:

• Constipation (most common)
• Dark or black stools (normal, not concerning)
• Nausea
• Stomach pain

Tips for tolerating iron:

• Start with lower dose and increase gradually
• Take with food (though this reduces absorption slightly)
• Use a stool softener if constipated
• Try different forms if one doesn't work

Intravenous (IV) Iron

When oral iron isn't working or isn't possible:

• Can't tolerate oral iron (severe side effects)
• Malabsorption: Celiac, gastric bypass, IBD
• Severe deficiency: Need rapid replenishment
• Pregnancy: When oral isn't working fast enough

Types of IV iron:

• Iron dextran
• Iron sucrose
• Ferric carboxymaltose
• Iron isomaltoside

Pros:

• Bypasses digestive system
• Replenishes stores quickly (1-2 visits vs. months of oral)
• Fewer GI side effects

Cons:

• Requires IV access
• More expensive
• Rare allergic reactions

Dietary Changes

Diet alone usually can't correct low ferritin, but it helps maintain levels once corrected:

Best iron sources:

Enhance absorption:

• Pair with vitamin C (citrus, bell peppers, strawberries)
• Cook in cast iron pans (adds iron to food)
• Avoid calcium with iron-rich meals
• Don't drink tea or coffee with meals

1. Assess Your Menstrual Bleeding

If you menstruate:

• How many days does your period last?
• How many products do you use per day?
• Do you pass clots?
• Do you bleed through at night?
• Does fatigue get worse during your period?

Heavy periods may need treatment (hormonal birth control, tranexamic acid, etc.)

2. Review Your Diet

• Do you eat red meat? How often?
• Are you vegetarian or vegan?
• Do you eat iron-rich plant foods?
• Do you drink tea or coffee with meals?
• Do you take calcium or antacids with meals?

3. Consider Your Risk Factors

• Frequent blood donor?
• Intense exercise (especially endurance)?
• Pregnant or breastfeeding?
• Recent surgery or major illness?
• Chronic digestive issues?

4. Don't Start High-Dose Iron Yet

Get ferritin tested first. Too much iron can be harmful, especially if you have hemochromatosis (genetic iron overload).

1. "What's causing my low ferritin?"
2. "Do I have iron deficiency anemia, or just low stores?"
3. "Do I need iron supplements?"
4. "What form of iron do you recommend?"
5. "Could my heavy periods be causing this?"
6. "Do I need testing for GI blood loss?"
7. "How long will it take to feel better?"
8. "When should we recheck my ferritin?"
9. "Could celiac disease or malabsorption be a factor?"
10. "Should I see a gynecologist about my periods?"

Low Ferritin in Athletes

Athletes often feel symptoms at higher ferritin levels:

• Some research suggests ferritin > 30 ng/mL for endurance athletes
• IV iron may be considered when oral isn't working
• May need ongoing maintenance even after levels normalize

Low Ferritin in Pregnancy

• Routine screening is recommended
• Low ferritin is very common
• Oral or IV iron depending on severity
• Postpartum, continue iron if breastfeeding

Low Ferritin in Men and Postmenopausal Women

ALWAYS evaluate for GI bleeding:

• Colonoscopy
• Upper endoscopy
• Test for H. pylori
• Consider celiac disease

Low ferritin means your iron stores are running low. You can have low ferritin without anemia and still have significant symptoms—fatigue, exercise intolerance, brain fog, hair loss.

Most common causes:

1. Inadequate dietary intake (especially vegetarians/vegans)
2. Menstrual blood loss (very common in premenopausal women)
3. Pregnancy or breastfeeding
4. GI blood loss (must be ruled out in men and postmenopausal women)

Treatment:

• Oral iron supplements for 3-6 months
• IV iron for severe cases or when oral isn't tolerated
• Address the underlying cause (heavy periods, GI issues, etc.)

Recovery timeline:

• You may start feeling better in 2-4 weeks
• Ferritin takes 3-6 months to fully replenish
• Continue supplements for 3-6 months after normalization to rebuild stores

Don't ignore low ferritin. It's your body's early warning system that iron stores are running low. Address it now before you develop anemia, and you'll feel like yourself again much sooner.

Related articles on WellAlly:

• Iron Deficiency Anemia: Complete Guide
• Heavy Menstrual Bleeding: When to Worry
• Best Iron-Rich Foods for Vegetarians
• Understanding Your Iron Panel Results