You’re exhausted. The most common symptom of iron deficiency, it’s also possibly the most difficult one to detect. “Women are so used to having frenetic lives and feeling tired,” says Nancy Berliner, M.D., deputy editor of Blood, the journal of the American Society of Hematology. “They often just dismiss being tired as part of life.” However, iron deficiency causes less oxygen to reach your tissues, so your body is deprived of the energy it needs. If your “normal” fatigue is coupled with you feeling, weak, irritable or unable to focus, iron (or a lack thereof) might have something to do with it. After all, there’s a reason people whose iron deficiency progresses into anemia are often said to have “tired blood.” You have heavy periods. In women, the number-one cause of iron deficiency is too-heavy periods, says Jacques Moritz, M.D., director of gynecology at Mount Sinai St. Luke’s Roosevelt in New York City. “They lose too much blood, replace about half of it, and then lose too much again the following month,” he says. “It’s like filling up a car with a small hold in the tank.” Your period should only fill two to three tablespoons each month. Try the tampon test: If you have to change your tampon more frequently than every two hours, talk to your gyno. You get short of breath easily. No matter how deeply you breathe, if your oxygen levels are low, you’ll feel out of air, explains Berliner. If you notice yourself getting out of breath doing things that you’d normally handle just fine — be it climbing a flight or stairs or knocking out your usual workout — iron deficiency could be to blame. 
Your heart is pounding. An overworked heart can end up suffering from irregular heartbeats, heart murmurs, enlargement, and even heart failure. Before you freak out, don’t. For things to get that bad, you would probably have to suffer from iron deficiency anemia for quite some time, suggests a review of cardiomyopathy and iron deficiency in the Texas Heart Institute Journal. However, if you know you have heart problems, it’s important to get your iron levels checked as iron deficiency can worsen existing heart problems. You have restless leg syndrome. Can’t stop fidgeting? About 15 percent of people with restless leg syndrome have iron deficiency, according to John Hopkins Medicine. The lower the iron levels, the worse the symptoms. Your head hurts. An iron-deficient body will prioritize getting oxygen to your brain before it worries about other tissues, but even then, your noggin will still get less than it ideally should, Berliner says. In response, the brain’s arteries can swell, causing headaches, according to the National Headache Foundation. You crave clay, dirt and ice. Called pica, craving (and actually eating) non-food substances can be a sign of of iron deficiency. Iron-deficient people may be tempted to chow down on chalk, clay, dirt and paper. Luckily, most women opt for ice, says Berliner, who tells her anemic patients to come back to see her if they start craving ice. You feel anxious for no reason. As if your life wasn’t stressful enough, iron deficiency can trick you into feeling even more anxious. A lack of oxygen revs up your body’s sympathetic nervous system, which is kind of like your body’s gas pedal, Berliner says. Plus, since iron deficiency can send your heart racing, it’s easy to feel like you’re in fight-or-flight mode even when you have every reason to feel relaxed. 
You’re losing your hair. Iron deficiency, especially when it progresses into full-blown iron deficiency anemia, can cause hair loss. “It sends your body into survival mode, so your body channels oxygen to support vital functions as opposed to ones like keeping your hair intact,” explains Moritz. Don’t panic if there are a few hairs in your drain, though. Most scalps lose about 100 hairs on a good day.
You’re vegetarian or vegan. All iron is not created equal. Your body absorbs heme iron — which comes from meat, poultry and fish — two to three times more efficiently than non-heme iron from plants, says nutritionist Rania Batayneh, author of The One One One Diet. You can still get enough iron with careful meal planning. Dark leafy greens, whole grains and legumes are all rich in iron; pair them with vitamin-C-rich foods like bell peppers, berries and broccoli to boost your absorption.
You have an under-active thyroid. Iron deficiency slows your body’s thyroid function and blocks its metabolism-boosting effects, according to the National Academy of Hypothyroidism. Hypothyroidism if often missed — six in 10 people with a thyroid disease don’t know they have it, according to the American Thyroid Association — so if you notice low energy levels, weight gain or even a lower body temperature, talk to your doc. You’re pregnant. Folic acid deservedly gets a lot of pre-natal press, but babies-to-be also need iron, and they can steal mom’s stores. What’s more, many women lose a substantial amount of blood during delivery, which can lower iron counts, Moritz says. If you’re pregnant with multiples, have pregnancies close together or regularly vomit because of morning sickness, you may need to boost your iron intake. 
Your tongue looks weird. Besides sapping the color out of your tongue, low iron counts can reduce levels of myoglobin, a protein in red blood cells that supports muscle health, like the muscle that makes up the tongue, Berliner says. As a result, many people who are iron deficient complain of a sore, inflamed and strangely smooth tongue.
You have celiac or inflammatory bowel disease. Even if you get enough iron in your diet, celiac disease and inflammatory bowel diseases like Crohn’s and ulcerative colitis can lead to problems absorbing nutrients, iron included. These conditions cause inflammation in and damage to the digestive tract. If you’ve been diagnosed with any of these GI diseases, talk to you doctor about how you can increase your iron absorption.
How To Get More Iron: Iron requirements aren’t one-size-fits-all, especially for women. Women between the ages of 19 and 50 typically need 18 milligrams per day. However, if you’re pregnant, that amount bumps up to 27 milligrams. If you’re breastfeeding, you should get just 9 milligrams. Plus, how heavy your periods are could also alter your needs. Older than 50 and not menstruating? You only need 8 milligrams per day. That’s not a hard target to hit — a single serving of lentils, spinach, beef, nuts, chicken or chickpeas will all score you at least a couple milligrams.
And when it comes to iron, more isn’t necessarily better. “While most the attention is on iron deficiency, there is a concern as well for iron overload, which studies indicate can damage internal organs and may increase the risk of diabetes, heart attack and cancer, particularly in older people,” Batayneh says. Try to hit your RDA of iron, but don’t worry about going above and beyond the recommendations.