Quick answer: the most common low ferritin symptoms are tiredness and weakness, followed by the signs of anemia once iron runs out: pale skin, shortness of breath, a fast heartbeat, dizziness and cold hands and feet, plus pica and restless legs. There is no single level where symptoms start: WHO calls under 15 ng/mL iron deficiency in healthy adults, but a trial in tired women without anemia treated anyone under 50 ng/mL, and US sleep doctors advise iron for restless legs at 75 ng/mL or less.
Each bar spans the ferritin levels that count as low under that rule. Sources: WHO 2020 ferritin guideline; American Gastroenterological Association 2020; Vaucher et al., CMAJ 2012; American Academy of Sleep Medicine 2025.
Low ferritin symptoms and how strong the evidence is
Ferritin is your iron reserve. It falls first; hemoglobin falls only once the reserve is used up, and the NHLBI notes that mild or moderate iron-deficiency anemia may cause no symptoms at all. That is why symptoms are a poor guide to your level, and why a blood test matters.
| Symptom | Listed by | What the evidence says |
|---|---|---|
| Tiredness, weakness | NHLBI, Cleveland Clinic | The most common. In a trial of 198 tired, non-anemic women with ferritin under 50 ng/mL, 12 weeks of iron cut fatigue scores by 47.7%, against 28.8% on placebo. A review of 18 trials found less self-reported fatigue with iron but no gain in measured physical capacity. |
| Shortness of breath, chest pain, fast heartbeat | NHLBI, Cleveland Clinic | Mainly once anemia develops and blood carries less oxygen |
| Pale skin, dizziness, cold hands and feet | NHLBI | Signs of anemia |
| Headaches, irritability, muscle cramps | Cleveland Clinic | Common but not specific to iron |
| Sore tongue, spoon-shaped nails | Cleveland Clinic | Physical signs a doctor looks for |
| Pica: craving non-food items such as ice or dirt | Cleveland Clinic | One of the more specific signs |
| Restless legs | AASM 2025, Cleveland Clinic | AASM advises iron for adults with restless legs when ferritin is 75 ng/mL or less or iron saturation is under 20% |
| Lower endurance, brain fog | Cleveland Clinic | Listed as complications of severe or untreated iron-deficiency anemia |
| Hair shedding | Olsen 2010, Trost 2006 | Weak evidence; see below |
Any of these can have other causes, including thyroid problems, low B12 and poor sleep. Our blood test for fatigue guide covers the full list.
What ferritin level counts as low
| Group | Low ferritin (ng/mL) | Source |
|---|---|---|
| Healthy infants and children under 5 | Under 12 | WHO 2020 |
| Healthy children 5 and older, teens and adults | Under 15 | WHO 2020 |
| Children under 5 with infection or inflammation | Under 30 | WHO 2020 |
| Age 5 and older with infection or inflammation | Under 70 | WHO 2020 |
| Pregnancy, first trimester | Under 15 | WHO 2020 |
| Adults with anemia | Under 45 | AGA 2020 |
| Adults with restless legs (iron advised) | 75 or less | AASM 2025 |
| Typical normal range, women / men | 13 to 150 / 30 to 400 | MedlinePlus |
WHO's 15 ng/mL cut-off is strict: it rarely labels someone deficient by mistake but misses many real cases, which is why the American Gastroenterological Association moved to 45 ng/mL for people with anemia. Ferritin also rises with infection and inflammation, so a normal-looking value can hide low iron; reading it next to hs-CRP helps. The full normal range, and what high ferritin means, is on our main ferritin guide.
Low ferritin in women and pregnancy
Menstruation makes low ferritin far more common in women. Among 3,490 non-pregnant US females aged 12 to 21 in NHANES, 38.6% had ferritin under 25 ng/mL, 17% were under 15 and 77.5% were under 50 (Weyand et al., JAMA 2023). Even 27.1% of girls who had not started their periods were under 25. Heavy periods, pregnancy, recent childbirth, frequent blood donation and weight-loss surgery all raise the risk (Cleveland Clinic).
In men and in women after menopause, low ferritin needs a cause: the AGA recommends examining the upper and lower gut in these groups when iron-deficiency anemia is found, because bleeding in the gut is a common source.
Pregnancy. WHO uses under 15 ng/mL in the first trimester and sets no fixed cut-off later, because blood volume expands and inflammation markers change as pregnancy goes on. The US Preventive Services Task Force (2024) found the evidence insufficient to recommend for or against routine iron screening or supplements in pregnant people without symptoms, so iron in pregnancy is a conversation for your prenatal care team.
Athletes and low ferritin
A 2019 review found iron deficiency in about 15% to 35% of female athlete groups and 5% to 11% of male athlete groups. Athletes lose iron through sweat, the breakdown of red cells from foot strike, blood in the urine and small gut bleeds, and the iron-regulating hormone hepcidin peaks 3 to 6 hours after exercise, blocking absorption from food. Timing iron-rich meals away from that window is one of the few levers. See our blood work for athletes guide.
Does low ferritin cause hair loss?
The evidence is weaker than many hair-loss articles suggest. In a Duke University study of 381 women with female pattern hair loss or chronic shedding and 76 women without hair loss, iron deficiency (ferritin 15 or less) was no more common in the hair-loss groups: 12.4% of premenopausal women with pattern hair loss against 29.8% of controls. Using 40 ng/mL, it was 58.8% against 72.3%. A Cleveland Clinic review concluded there is not enough evidence to screen everyone with hair loss for iron or to give iron to non-anemic patients for hair loss, though its own clinic does screen. Our blood test for hair loss guide covers the other markers.
Worked examples
A 34-year-old woman with heavy periods, exhausted, hemoglobin 12.6 g/dL, ferritin 18 ng/mL, normal hs-CRP. Not iron deficient by WHO's 15 line, and not anemic, so the AGA's 45 cut-off does not strictly apply. She would have qualified for the French fatigue trial (ferritin under 50, hemoglobin over 12), where iron beat placebo on fatigue. That makes iron, and the heavy periods behind it, worth raising with her doctor rather than self-treating: too much iron is harmful.
A 29-year-old male distance runner with ferritin 28 ng/mL and normal hemoglobin. Above WHO's 15 but under the 30 ng/mL start of MedlinePlus's normal range for men. Common in endurance athletes; diet, meal timing and a retest are the usual first steps with a doctor.
A 60-year-old man with ferritin 11 ng/mL and anemia. Iron deficient on every scale. The AGA recommends a gut evaluation for men with iron-deficiency anemia, so this needs a prompt doctor visit.
How to test ferritin at home
| SiPhox panel | Iron markers | Also useful here | Per test with shipping |
|---|---|---|---|
| Longevity Essentials | Ferritin, hemoglobin, hematocrit | hs-CRP, vitamin D | $149 |
| Thyroid Focus | Ferritin (no hemoglobin) | Full thyroid panel, hs-CRP | $149 |
| Ultimate 360 | Ferritin, iron, TIBC, UIBC, iron saturation, hemoglobin | B12, folate, hs-CRP, thyroid | $274 |
| GLP Optimization | Ferritin, iron, TIBC, UIBC, iron saturation, hemoglobin | B12, folate, vitamin D | $224 |
Heart & Metabolic and Hormone Focus do not include ferritin.
| If you have | Test | Choose |
|---|---|---|
| Tiredness and want a first check | Ferritin, hemoglobin, hs-CRP | Longevity Essentials ($124 + $25) |
| Tiredness with possible thyroid symptoms | Ferritin plus TSH, free T4, free T3 | Thyroid Focus ($124 + $25) |
| Restless legs (AASM uses ferritin and iron saturation) | Ferritin and the full iron panel | Ultimate 360 ($249 + $25) |
| Known low ferritin and treatment to track | Ferritin, iron saturation, hemoglobin | Ultimate 360 or Longevity Essentials |
| Pregnancy | Prenatal blood tests | Your prenatal care team |
For a doctor to separate low iron from other causes, the full iron panel (serum iron, TIBC and saturation) and hemoglobin matter as much as ferritin. More kits are compared in our iron test at home guide.
A note on home samples: SiPhox's partner lab tests capillary blood collected from the upper arm. SiPhox says its results show a 95% to 99% correlation with venous draws in its own quarterly comparisons against Labcorp and Quest, but it has not published a study of the EasyDraw device, and results come without an included doctor review. If a result would change a treatment decision, confirm it with a venous test through your doctor.
Longevity Essentials
The default panel: heart, metabolic, hormone and inflammation markers in one draw.
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Thyroid Focus
A full thyroid workup including both thyroid antibodies, plus core lipids.
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Everything on the four core panels plus iron studies, B12 and folate, GGT and PSA.
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Frequently asked questions
What ferritin level causes symptoms?
There is no single level. WHO defines iron deficiency as under 15 ng/mL in healthy adults, a fatigue trial in women without anemia treated anyone under 50 ng/mL, and US sleep doctors advise iron for restless legs at 75 ng/mL or less. Many people with mild iron deficiency feel nothing.
What are the symptoms of low ferritin in women?
The same as in men: tiredness, weakness, pale skin, shortness of breath, headaches, cold hands and feet, pica and restless legs. Women are far more often affected; 38.6% of US females aged 12 to 21 had ferritin under 25 ng/mL in NHANES.
Can low ferritin cause hair loss?
Possibly, but the evidence is weak. A study of 457 women found iron deficiency was no more common in women with pattern hair loss or chronic shedding than in women without hair loss, and a Cleveland Clinic review found too little evidence to screen everyone.
Can you have low ferritin without anemia?
Yes. Ferritin falls before hemoglobin does, so iron deficiency without anemia is common. The French fatigue trial enrolled only women with normal hemoglobin (over 12 g/dL) and ferritin under 50 ng/mL.
How long does it take to raise ferritin?
Weeks to months. In the French trial, 80 mg of elemental iron a day for 12 weeks raised ferritin by 11.4 ng/mL more than placebo. Take iron only on a doctor's advice and retest to check the effect.
Sources
- WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations (2020)
- Ko CW et al. AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia. Gastroenterology 2020
- Vaucher P et al. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ 2012
- Houston BL et al. Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review. BMJ Open 2018
- Winkelman JW et al. Treatment of restless legs syndrome and periodic limb movement disorder: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med 2025
- Weyand AC et al. Prevalence of iron deficiency and iron-deficiency anemia in US females aged 12-21 years, 2003-2020. JAMA 2023
- Sim M et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol 2019
- Fensham N et al. Parenteral iron therapy: examining current evidence for use in athletes. Int J Sports Med 2024
- Olsen EA et al. Iron deficiency in female pattern hair loss, chronic telogen effluvium, and control groups. J Am Acad Dermatol 2010
- Trost LB et al. The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol 2006
- NHLBI: Iron-deficiency anemia
- Cleveland Clinic: Iron-deficiency anemia
- MedlinePlus: Ferritin blood test
- US Preventive Services Task Force: Iron deficiency and iron deficiency anemia during pregnancy, screening and supplementation (2024)
- SiPhox Health: panel comparison (checked 29 Sep 2026)
- SiPhox Health: Longevity Essentials panel
- SiPhox Health: Ultimate 360 panel