The earliest signs that you need more iron are often vague: persistent fatigue, feeling winded during exercise you used to handle fine, and a general sense of weakness. These symptoms overlap with dozens of other conditions, which is why iron deficiency frequently goes undiagnosed. A simple blood test measuring your ferritin level (the protein that stores iron inside your cells) is the only reliable way to confirm it. A ferritin level below 30 nanograms per milliliter indicates depleted iron stores, even if you haven’t yet developed full-blown anemia.
Common Symptoms to Watch For
Iron deficiency symptoms are notoriously nonspecific, meaning they could point to many things. The most common ones include fatigue, generalized weakness, lightheadedness, and dizziness. You might also notice pale skin or paleness in the whites of your eyes, shortness of breath during activity, headaches, cold hands or feet, and brittle nails.
Some symptoms are more distinctive. Craving and chewing ice is one of the most common yet least talked-about signs. This falls under a broader category called pica, where your body drives you to eat non-nutritive things like ice, starch, or other unusual items. In more advanced deficiency, your nails can flatten and eventually develop a spoon-shaped indentation deep enough to hold a drop of water. These “spoon nails” develop gradually and are strongly associated with iron deficiency anemia.
Here’s the important part: you can have real symptoms before anemia ever shows up on a standard blood count. When your iron stores are low but your hemoglobin is still technically in the normal range, you may already feel fatigued, foggy, or exercise-intolerant. This is why ferritin testing matters, not just a basic blood count.
Who Is Most Likely to Be Low
Your daily iron needs vary dramatically depending on your age, sex, and life stage. Women between 19 and 50 need 18 mg per day, more than double the 8 mg men in the same age range need. The gap exists because of menstrual blood loss. During pregnancy, the requirement jumps to 27 mg per day. After menopause, women’s needs drop back to 8 mg, matching men’s.
Beyond these groups, people at higher risk include those with heavy periods, frequent blood donors, people with digestive conditions that impair absorption (like celiac disease or inflammatory bowel disease), and anyone following a strictly plant-based diet. Endurance athletes also lose iron through sweat and a process called foot-strike hemolysis, where red blood cells break down from repetitive impact.
Why Your Diet Might Not Be Enough
Not all dietary iron is created equal. Iron from animal sources like meat, poultry, and seafood is absorbed at a rate of 25 to 30 percent. Iron from plant sources like beans, grains, and spinach is absorbed at roughly 3 to 5 percent. That’s a six- to tenfold difference in how much actually reaches your bloodstream.
Several common foods and drinks make absorption even worse. Tea, coffee, and legumes contain tannins that reduce iron uptake. Whole grains, seeds, and nuts contain phytic acid, which blocks iron, zinc, magnesium, and calcium absorption. One review found these compounds reduced non-heme iron absorption by anywhere from 1 to 23 percent, depending on the amount consumed. Calcium also competes with iron for absorption, so taking an iron-rich meal alongside a glass of milk or a calcium supplement can blunt the benefit.
Vitamin C has the opposite effect. Eating iron-rich foods alongside citrus fruits, bell peppers, or tomatoes significantly improves absorption of plant-based iron. If you’re relying on non-animal sources, pairing them with something acidic at the same meal makes a real difference.
How Iron Deficiency Gets Confirmed
If you suspect you’re low, a blood test is the next step. The most useful single test is serum ferritin. Typical ferritin ranges are 24 to 336 micrograms per liter for men and 11 to 307 for women. Results below the lower end of those ranges point to iron deficiency. Your doctor may also check hemoglobin, which tells you whether the deficiency has progressed to anemia.
Screening recommendations vary. The American College of Obstetricians and Gynecologists and the CDC recommend that all pregnant people be screened for anemia at their first prenatal visit, with a repeat screen at 24 to 28 weeks. Outside of pregnancy, there’s no universal screening guideline for the general population. Testing is typically driven by symptoms or risk factors.
Why You Shouldn’t Supplement Without Testing
Iron is one of the few nutrients where more is genuinely dangerous. Your body has no efficient way to dump excess iron, so it accumulates in organs over time. A genetic condition called hemochromatosis causes the body to absorb too much iron, and it can lead to liver damage, liver cancer, heart problems, diabetes, and joint disease. About 1 in 200 people of Northern European descent carry the gene combination for this condition, and many don’t know it.
Even without hemochromatosis, taking iron supplements when you don’t need them can cause nausea, constipation, and stomach pain, and chronically elevated iron is toxic to tissues. This is why getting a ferritin test before starting supplements matters. If your levels are normal, the symptoms you’re experiencing have a different cause, and adding iron won’t help. If your levels are genuinely low, you and your doctor can choose the right dose and form, then retest in a few months to confirm it’s working.
What Low Iron Feels Like Day to Day
People often describe iron deficiency as feeling like they’re running on empty no matter how much they sleep. You might wake up tired, struggle to concentrate at work, or find yourself breathless walking up a flight of stairs that never used to bother you. Some people notice their hair thinning or falling out more than usual. Others get restless legs at night, an uncomfortable urge to move their legs that disrupts sleep and compounds the fatigue.
The tricky part is that these symptoms creep in gradually. Your body compensates for declining iron stores over weeks and months, so you adjust to feeling slightly worse without recognizing a clear starting point. Many people only realize how bad they felt after their levels are corrected and their energy returns. If you’ve been chalking up persistent tiredness to stress, poor sleep, or just getting older, and especially if you fall into a higher-risk group, a ferritin test can give you a concrete answer.