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Iron is essential to your health — especially if you menstruate. It plays a critical role in producing hemoglobin, the protein in red blood cells that carries oxygen throughout your body. When you don’t have enough iron, everything from your energy levels to your immune system can take a hit.
Iron is super important because our bodies use it to make red blood cells. These cells help carry oxygen around our body, keeping us healthy and energized. And if your levels get severely low, you could develop iron deficiency anemia, but being low on iron doesn’t automatically put you in the anemic category.
Heavy periods are to blame for the disproportionate number of women struggling with low iron. “Approximately 35% of all women of reproductive age in the US have iron deficiency anemia,” says Board Certified OB/GYN Dr. Christy Evans, M.D. of Almond ObGyn. And this number is substantially higher in developing countries, adds Evans.
Signs you have low iron
Iron deficiency can look different from person to person, but these 15 signs are among the most common — and often easy to ignore. Whether you’re dealing with vague fatigue or something more specific, your body could be asking for help.
1. Persistent fatigue
Ongoing tiredness is one of the most common — and overlooked — symptoms of iron deficiency. This isn’t your typical “I stayed up too late” fatigue. It’s the kind of exhaustion that makes everyday tasks feel like climbing a mountain. That’s because when your body doesn’t have enough iron, it can’t produce enough hemoglobin to deliver oxygen to your tissues. Without enough oxygen, your muscles and organs have to work harder, which drains your energy faster. This symptom can sneak up gradually, but if you feel constantly run-down despite sleeping well, low iron might be the reason.
"Iron deficiency can negatively impact women by reducing their exercise capacity and negatively impacting their quality of life,” says Preventive Cardiology Dietitian Michelle Routhenstein, MS, RD, CDE, CDN.
2. Pale or dull skin
Your skin can offer an early clue about what’s happening inside your body. When you’re iron deficient, your hemoglobin levels drop — and that affects the reddish hue in your blood. This can make your skin look paler than usual or give you a “washed out” appearance, especially in areas like your face, the inside of your eyelids, your gums, and nail beds. If your usual complexion seems a little off — or if friends are asking if you’re feeling okay — it could be due to lower iron levels.
3. Increased hair loss
Everyone sheds hair, but noticeable thinning — like more strands in the drain, on your pillow, or clumped in your hairbrush — can point to iron deficiency. Iron helps support hair follicle cell turnover and oxygen flow to the scalp. When your body is low on iron, it prioritizes essential functions (like keeping your heart beating) over less critical ones (like growing hair). This can put hair follicles into a resting phase, leading to increased shedding and slower regrowth.
4. Brittle or weak nails
Your nails are another place where iron deficiency shows up. Low iron can lead to dry, thin, or brittle nails that crack and split easily. In more advanced cases, your nails may even become spoon-shaped — concave and curved upward at the edges — a condition known as koilonychia. This happens when not enough oxygen is reaching the nail beds to keep them strong and healthy.
5. Shortness of breath
If walking across a parking lot or climbing a single flight of stairs leaves you unusually breathless, that’s a red flag. Your muscles rely on oxygen to function properly. When iron levels are low, your hemoglobin levels drop, reducing the oxygen-carrying capacity of your blood. This can make your lungs and heart work overtime, leaving you short of breath even with mild exertion. You don’t have to be a runner to notice this one.
6. Restless leg syndrome
Restless leg syndrome (RLS) is that uncomfortable, irresistible urge to move your legs — usually in the evenings or when you’re trying to relax. It’s a neurological condition that can be linked to low iron levels, especially in the brain. If your legs feel twitchy, tingly, or hard to settle at night, RLS could be one more sign of an underlying iron deficiency.
Routhenstein points out that a decline in dopamine levels due to low iron is the culprit, but added that providers may not see iron deficiency as a cause of restless leg syndrome in many cases.
7. Frequent illness or infections
Iron is vital for immune function. It supports the growth and activity of immune cells that help your body fight off viruses and bacteria. If you find yourself constantly dealing with colds, infections, or taking longer to recover than usual, your immune system might be underpowered due to a lack of iron. While no one loves getting sick, if it’s happening more often than it should, your iron levels might be worth checking.
"Iron is necessary for immune cells to fight infection," says Routhenstein. “When iron levels are low, it negatively impacts the immune response, leading to more frequent infections."
8. Feeling cold all the time
Always reaching for a sweater when everyone else is fine? That constant chill could be a result of low iron. Iron plays a role in maintaining a healthy metabolism and regulating body temperature. Without enough of it, your body may struggle to generate and distribute heat efficiently. People with iron deficiency often report feeling cold even in warm environments, or having freezing hands and feet.
9. Regular headaches
Headaches from time to time are common. But if you’ve started experiencing them more frequently — especially alongside fatigue or lightheadedness — iron deficiency could be contributing. Without enough oxygen-rich blood reaching the brain, blood vessels may swell and trigger pressure and pain. Studies have shown that iron-deficiency anemia is linked to increased severity of chronic daily headaches and even migraines.
10. Dizziness or lightheadedness
Low iron can leave you feeling off balance, especially when you stand up quickly or change positions. Dizziness happens when your brain isn’t receiving enough oxygen-rich blood, which can be a direct result of low hemoglobin. In more serious cases, this can lead to fainting or a general feeling of instability — especially if paired with fatigue, weakness, or shortness of breath.
11. Irregular or rapid heartbeat
Your heart has to pump harder and faster when there’s less oxygen in your bloodstream. Over time, this added strain can lead to an irregular heartbeat (arrhythmia), palpitations, or a racing pulse — even when you’re at rest.
This symptom isn’t one to take lightly and can lead to more severe heart problems down the line. "Iron deficiency is associated with an increased risk of heart disease and irregular heartbeat due to low iron levels decreasing oxygen delivery to your body,” says Routhenstein.
If your heart feels like it’s skipping beats or racing without exertion, don’t ignore it.
12. Unusual cravings (pica)
“One of the more unusual symptoms of iron deficiency is pica, which is unusual cravings for non-nutritive substances, such as ice, dirt, or starch,” says Evans.
Pica is a strange but well-documented symptom of iron deficiency. These pica cravings can be strong and hard to resist, and they often disappear once iron levels are restored. If you find yourself constantly chewing ice or craving things you know you shouldn’t be eating, it’s worth flagging to your doctor.
13. Brain fog or difficulty concentrating
“Moderate to severe anemia can cause difficulty concentrating”, says Evans. Feeling mentally sluggish, forgetful, or foggy can be directly related to low iron. Iron is essential for proper brain function and the production of neurotransmitters that regulate mood and mental clarity. When oxygen delivery to the brain is reduced, it becomes harder to focus, retain information, or stay mentally sharp. If you feel like your brain isn’t firing on all cylinders, iron might be a factor.
14. A sore or swollen tongue
An inflamed or swollen tongue — medically known as glossitis — is a classic but often overlooked sign of iron deficiency. Your tongue may look unusually smooth, red, or swollen, and it might feel tender or sore. You could also experience cracks at the corners of your mouth, difficulty swallowing, or changes in how food tastes. These symptoms can develop gradually and are easily missed, but they often improve with iron supplementation.
15. Slow wound healing
If cuts, scrapes, or bruises are taking longer than normal to heal, low iron could be interfering with your body’s repair process. Iron supports cell regeneration, tissue growth, and immune responses — all of which are critical for proper healing. A deficiency slows everything down, making minor injuries linger longer than they should.
Behavioral symptoms of iron deficiency in adults
Low iron doesn’t just affect your body — it can affect your mood, focus, and day-to-day behaviors, too.
Common behavioral symptoms in adults include:
- Irritability or mood swings: Iron helps regulate neurotransmitters like dopamine and serotonin, so low levels may affect your emotional stability.
- Sleep issues: You might feel exhausted but struggle to fall asleep or stay asleep — especially if restless legs are in the mix.
- Withdrawal or low motivation: It’s harder to stay social or upbeat when your energy and mental clarity are depleted.
- Anxiety or increased stress response: Some people with iron deficiency experience heightened anxiety, especially when other symptoms are misattributed to emotional causes.
It’s easy to chalk these issues up to a stressful week or a bad night’s sleep, but they could be symptoms of a bigger underlying issue.
How do you know if you need iron?
If any of the signs above feel familiar, the next step is simple: talk to your healthcare provider. A quick blood test can check your hemoglobin and ferritin levels to determine if you’re deficient — or trending in that direction.
If you are low on iron, treatment options vary. Some people respond well to dietary changes (think red meat, lentils, tofu, spinach), while others benefit from iron supplements.
For those who’ve struggled with traditional supplements — whether due to nausea, constipation, or just poor absorption — ACCRUFeR may be a helpful option to explore. It’s a twice-daily prescription iron treatment designed to restore your levels without disrupting your gut. Clinical research shows most people see improved hemoglobin levels in 12 weeks, with some noticing changes in as little as four.
Iron deficiency is common — but it's not something to ignore
You don’t have to feel awful to have low iron — but your body will eventually start giving you signals when it needs more support. Whether it’s fatigue you can’t shake, thinning hair, weird cravings, or brain fog that won’t lift, it’s worth listening to those signs.
The good news? Iron deficiency is treatable. With the right support — whether that’s a dietary shift or a prescription like ACCRUFeR — you can rebuild your iron stores, reclaim your energy, and feel like yourself again.
Because your body is always talking to you. And you deserve to feel your best.
Tassia O'Callaghan is an experienced content writer and strategist, having written about a vast range of topics from chemical regulations to parenting, for brands like Peanut App Ltd, Scary Mommy, Tally Workspace, and Office Christmas. She's an advocate for realistic sustainable living, supporting small businesses (author of A-Z of Marketing for Small Businesses), and equity across all walks of life. Follow her on LinkedIn or TikTok, or see more of her work on Authory or her website.