Can Iron Deficiency Cause Heavy Periods?

It’s a chicken-and-egg question: does iron deficiency, a condition caused by losing too much iron from your red blood cells, cause heavy periods, or do heavy periods cause iron deficiency? With up to one-third of women suffering from some form of iron deficiency due to heavy periods, it’s no wonder so many of us are curious!

The truth is, it can go both ways. Low iron levels can make periods heavier and longer, while heavy bleeding can drain your body’s iron stores over time. It’s a cycle that can leave you feeling exhausted, dizzy, or foggy-headed every month, yet too often, these symptoms are brushed off as “just part of having a period.”

If this sounds familiar, you’re not alone, and you’re certainly not imagining it. Understanding the connection between iron and your menstrual health is the first step to feeling more like yourself again.

What is iron deficiency anemia?

Iron deficiency happens when your body does not have enough iron to produce hemoglobin (the protein in your red blood cells that carries oxygen throughout your body). Without enough iron, your tissues and organs receive less oxygen, leaving you feeling drained, dizzy, and short of breath.

Iron deficiency exists on a spectrum. In the early stages, your body simply runs low on stored iron, a state known as iron depletion. As levels drop further, it becomes iron deficiency, where red blood cell production starts to suffer. If left untreated, this can progress to iron deficiency anemia, the most severe stage, where your red blood cells are too few or too weak to meet your body’s needs.

It’s more common than most people realise. According to new research, more than 1 in 3 women under 50 are iron-deficient, and around 10% develop full iron deficiency anemia. The risk is even higher for those with heavy menstrual bleeding, as monthly blood loss can quickly deplete iron stores.

Women with mild or moderate deficiency might experience symptoms like weakness, extreme fatigue, headaches, dizziness, and brittle nails. As the condition worsens, symptoms can include shortness of breath, rapid heartbeat, or unusual cravings for non-food items such as ice or dirt, a condition known as pica.

The good news? Iron deficiency is highly treatable through dietary changes and medication, including iron supplements or iron-rich foods like red meat, lentils, spinach, and fortified cereals.

Still, it remains one of the most underdiagnosed conditions in women. As Dr. Malcolm Munro, professor of obstetrics and gynecology, noted in a study published by the American College of Obstetrics and Gynecology, symptoms such as fatigue and lightheadedness are “frequently normalized by society.” In other words, many women are told their exhaustion is just part of life, when in reality, it may be a sign that their body is running on empty.

Iron deficiency vs. iron deficiency anemia: What's the difference?

Think of iron deficiency and iron deficiency anemia as two points on the same spectrum. Both are related to low iron levels, but the difference lies in how severely your body is affected.

Iron deficiency occurs when your body’s iron stores start to run low. This can happen if you are not getting enough iron through your diet, if you are losing blood (for example, through heavy periods), or if your body struggles to absorb iron properly. At this stage, your red blood cells can still function, but your body is already working harder to keep oxygen flowing. You might notice subtle signs like tiredness, pale skin, or feeling out of breath after mild exertion.

If the deficiency continues and your body can no longer produce enough healthy red blood cells, it progresses to iron deficiency anemia. This is the point where your hemoglobin levels drop below normal, reducing your blood’s capacity to carry oxygen. According to the World Health Organization, anemia affects roughly 30% of women worldwide and can lead to more serious symptoms such as dizziness, chest pain, and rapid heartbeat.

Both iron deficiency and iron deficiency anemia require attention, but anemia typically needs more targeted treatment, often a combination of iron supplements or infusions prescribed by your healthcare provider and regular follow-ups to monitor recovery. Catching iron deficiency before it becomes anemia can help prevent more serious symptoms and restore your energy levels faster.

What causes iron deficiency in women?

There is no single cause of iron deficiency, and iron deficiency can happen in many different stages of your life. Not getting enough iron in your diet, or losing iron through blood loss and pregnancy, can all contribute to iron deficiency over time.

Heavy menstrual bleeding and iron loss

Your red blood cells carry iron through your body, so blood loss from heavy periods can quickly deplete your iron stores. A typical period leads to a loss of around 16–32 milligrams of iron, but with heavy bleeding, that number can rise to 80 milligrams or more, making it difficult to replace through food alone.

“Heavy” or menorrhagic periods are usually defined as bleeding that lasts more than eight days or requires changing a pad or tampon every hour. You might also notice large clots or bleeding through your clothes or bedding.

When this happens month after month, your body struggles to rebuild its iron and red blood cell supply, which can eventually lead to iron deficiency anemia. According to the American College of Obstetricians and Gynecologists, heavy menstrual bleeding is one of the most common causes of anemia in people who menstruate. If you often feel unusually tired, dizzy, or out of breath during your period, it may be time to get your iron levels checked.

Diet and absorption issues

Your body gets iron from the foods that you eat, like meat, poultry, and leafy greens. Not getting enough iron from your diet can cause iron deficiency. Vegetarians and vegans are more likely to be iron-deficient than those who eat meat, which is why many doctors recommend supplementing a vegetarian diet with plenty of iron-rich foods.

Pregnancy and other factors

Pregnant women need extra iron in their diet because their bodies are hard at work supplying blood to their fetuses! The World Health Organization recommends iron-containing supplements to pregnant women to support fetal development and reduce the risk of iron deficiency throughout pregnancy.

Can iron deficiency cause heavy periods? The vicious cycle

Heavy periods cause your body to lose red blood cells, which in turn can deplete your iron stores. Each month, as you shed blood through your period, you also lose a portion of your body’s iron supply, and if your diet or supplements do not replace it fast enough, your levels can drop. This is one of the most common causes of iron deficiency in people who menstruate.

But here’s where it gets tricky: research shows the relationship can go both ways. Not only can heavy bleeding lead to iron deficiency, but low iron levels may also make periods heavier. A study published in JAMA found that women with iron deficiency were more likely to experience prolonged or excessive menstrual bleeding.

Why? Iron plays a vital role in vascular constriction, which helps your blood vessels tighten and slow the flow of bleeding. When your iron stores are low, your capillaries cannot constrict as efficiently. This reduced vessel tone can lead to heavier, longer-lasting bleeding, which then causes even greater iron loss. It’s a self-perpetuating cycle: heavy bleeding drains your iron, low iron weakens your body’s ability to manage blood loss, and the cycle continues.

Iron deficiency is not the only cause of heavy periods, though. Conditions like endometriosis, uterine fibroids, thyroid imbalance, and blood-clotting disorders can also contribute to heavy bleeding. That’s why it’s important to talk to your healthcare provider if you notice your periods becoming heavier or more exhausting over time. Understanding what’s behind your symptoms is the first step to breaking the cycle and feeling like yourself again.

How to tell if you have low iron during your period

It’s not always easy to tell when your iron levels are dipping, especially since many of the symptoms can feel like typical period side effects. Fatigue, brain fog, and mood changes might seem normal when you are bleeding each month, but they can also be signs that your body is running low on iron.

Low iron during your period can sneak up on you gradually, leaving you feeling more wiped out, lightheaded, or short of breath with each cycle. The tricky part? These symptoms often overlap with PMS or general stress, which means they’re easy to miss or dismiss.

In the next section, we’ll look more closely at the telltale signs of low iron during your period, and how to know when it might be time to get tested.

Low iron symptoms in women during menstruation

Feeling extra tired or foggy during your period might not just be hormonal; it could be your body’s way of signaling low iron. Because iron helps deliver oxygen to your muscles and organs, low levels can make your usual period symptoms hit harder and last longer. If you find yourself feeling unusually drained or dizzy each month, your body might be running low on its iron reserves.

Here are some of the most common signs of low iron during your period to watch out for:

• Fatigue and weakness: Feeling exhausted even after resting, or struggling to get through your usual routine while menstruating.
• Lightheadedness or dizziness: Standing up too quickly or losing focus easily could be due to a temporary dip in blood oxygen.
• Worsening period symptoms: Heavier cramps, longer bleeding, or more intense PMS can all be linked to low iron levels.
• Brain fog and poor concentration: Difficulty focusing or finding the right words, often mistaken for stress or lack of sleep.
• Shortness of breath: Feeling winded after climbing stairs or doing light activity, even outside your heaviest flow days.
• Cold hands and feet: Poor circulation from reduced red blood cell production can leave your extremities chilly.

These symptoms can build slowly over time, making them easy to overlook. Paying attention to how your body feels during your cycle can help you catch low iron early, before it starts affecting your everyday life.

Physical signs of anemia and periods

When your body is running low on iron for too long, it can start to show on the outside as well as how you feel. These physical signs are your body’s way of waving a red flag, especially if they appear around or after your period. Anemia reduces your red blood cell count, which means less oxygen reaches your tissues, and that lack of oxygen can affect everything from your skin tone to your heartbeat.

Here are some of the more visible signs to look out for:

• Pale skin or nail beds: A noticeable loss of colour in your face, lips, or nails can be a sign of reduced red blood cell production.
• Brittle nails: Iron helps support healthy nail growth, so nails that chip or split easily may signal low iron.
• Hair loss: When your body is short on iron, it prioritises vital organs over hair follicles, leading to shedding or thinning.
• Craving ice (pica): An unusual urge to chew ice is a common but often overlooked symptom of iron deficiency anemia.
• Rapid heartbeat: Your heart may beat faster as it tries to compensate for lower oxygen levels in your blood.

If you notice one or more of these changes, particularly alongside heavy periods, it could be worth asking your doctor for a simple blood test to check your iron and hemoglobin levels.

How much iron do you lose on your period?

It might not seem like much, but every drop of blood lost during your period contains iron. Over time, that adds up, especially if your flow is heavy.

According to the National Institutes of Health (NIH), a typical period leads to a blood loss of around 30 to 40 millilitres per cycle, which equals roughly 15 to 30 milligrams of iron. For someone with heavy menstrual bleeding (defined by the American College of Obstetricians and Gynecologists as losing more than 80 millilitres of blood per cycle) iron loss can climb above 80 milligrams. That’s more than double what most women can replace through diet alone.

Even a normal period can cause small but measurable changes in blood markers. Studies show that hemoglobin levels (the protein that carries oxygen) can drop slightly during menstruation, while ferritin, which reflects stored iron, may fall anywhere from 4mg to 50mg during your period before gradually recovering across the cycle. For most people, these shifts are temporary. But for those with consistently heavy bleeding, low ferritin levels can linger, increasing the risk of iron deficiency anemia.

What’s considered “normal” varies from person to person, but if your periods last longer than eight days, if you frequently bleed through pads or tampons, or if you feel unusually tired or lightheaded, it might be a sign that your blood loss is affecting your iron stores. In that case, it’s worth asking your doctor about checking your hemoglobin and ferritin levels, a simple blood test that can help confirm whether your period is taking more out of you than it should.

Does anemia affect your period? How low iron changes your cycle

Anemia doesn’t just make you feel tired; it can also change the way your body bleeds each month. Because iron is essential for healthy blood production and oxygen flow, low levels can throw your menstrual cycle off balance. Some people notice heavier or longer bleeding, while others might skip periods altogether as the body tries to conserve energy and nutrients.

If your cycle has suddenly shifted, whether it’s becoming heavier, lighter, or more irregular, anemia could be playing a role. In the next sections, we’ll explore exactly how low iron affects your hormones, uterine lining, and overall menstrual health, and what you can do to restore balance.

Can low iron cause heavy periods?

Yes, low iron can make your periods heavier. While heavy bleeding often causes iron deficiency, the reverse is also true.

Iron helps your uterine blood vessels constrict and slow bleeding during your period. When iron levels are low, these vessels cannot tighten as effectively, which can lead to heavier, longer flow.

This creates a frustrating cycle: heavy periods drain your iron, and low iron makes them even heavier. Addressing the deficiency can often help ease both the fatigue and the bleeding.

Can anemia cause irregular periods?

Yes, anemia can affect the regularity of your menstrual cycle. When your body doesn’t have enough iron to make healthy red blood cells, it struggles to deliver oxygen efficiently to your organs, including the ovaries and uterus. This can disrupt the delicate hormonal balance that controls your menstrual cycle.

Iron deficiency and anemia are linked to lower levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), both of which are needed for ovulation. Without regular ovulation, your periods can become lighter, shorter, delayed, or even stop altogether. A 2020 study found that women with anemia were more likely to experience menstrual irregularities compared to those with normal iron levels.

Can low iron cause missed or late periods?

Yes, in some cases, low iron or anemia can cause your period to arrive late or stop altogether. When your body becomes severely iron deficient, it shifts into “energy-saving” mode, prioritising essential functions like heart and brain activity over reproduction. This can suppress ovulation and delay or pause your menstrual cycle.

Chronic anemia can also disrupt the hypothalamic-pituitary-ovarian axis, the hormonal pathway that regulates your cycle. Without enough oxygen reaching the ovaries, hormone production can falter, leading to missed or irregular periods.

Does anemia make you bleed more on your period?

Yes, anemia can make your periods heavier or longer, especially if it’s caused by iron deficiency. The link works both ways: heavy bleeding can lead to anemia, and anemia can make bleeding worse.

Iron plays an essential role in helping your blood vessels constrict, and your uterus control blood flow. When your iron levels are too low, your capillaries lose some of that tone, meaning they can’t tighten as efficiently to slow bleeding. Research from 2023 found that iron deficiency reduces vascular resistance, which can lead to heavier menstrual flow.

Heavy period anemia: When to worry

It can be hard to know when a heavy period crosses the line from “normal” to something worth checking out, especially when we’re taught that bad cramps and big clots are just part of the deal. But if your periods regularly leave you feeling exhausted, dizzy, or unable to go about your day, your body may be losing more blood (and iron) than it can replace.

According to the American College of Obstetricians and Gynecologists (ACOG), you should talk to your healthcare provider if you notice any of the following:

• Changing your pad or tampon every hour or less for several hours in a row
• Bleeding longer than eight days
• Passing blood clots larger than a quarter or multiple large clots in a single period
• Feeling extremely tired, dizzy, short of breath, or pale during or after your period

If any of these symptoms sound familiar, you don’t need to “just deal with it.” A doctor can run simple tests (like checking your hemoglobin and ferritin levels) and recommend treatment options to help lighten your flow, restore your iron, and get you feeling stronger again.

How to find out if you're iron-deficient

You deserve to feel good and strong. Despite its shocking prevalence among younger women, iron deficiency screenings aren’t regularly included in routine blood work, so it’s important to advocate for yourself to your provider if you suspect that you have an iron deficiency.

Talk to your provider: Tests you need

If you suspect that heavy periods or fatigue are linked to low iron, the best next step is to talk to your healthcare provider. Iron deficiency can’t always be diagnosed based on symptoms alone. Many people go years without realising their exhaustion or lightheadedness is due to low iron. Fortunately, a few simple blood tests can reveal what’s really going on.

Here’s what to ask about:

• Ferritin: This measures your body’s stored iron and is often the most accurate early indicator of deficiency. Low ferritin levels (typically under 30 ng/mL) suggest your reserves are running low, even before anemia develops.
• Hemoglobin and hematocrit: These tests show how many red blood cells you have and how concentrated your blood is. Low levels indicate that iron deficiency has already progressed to anemia.
• Serum iron and total iron-binding capacity (TIBC): These measure how much iron is circulating in your blood and how well it’s being transported. A low serum iron level combined with a high TIBC can confirm iron deficiency.

According to Yale Medicine, routine screening for iron deficiency isn’t standard for menstruating women, despite how common it is. That means you might have to advocate for yourself, especially if you have heavy periods, fatigue, or other symptoms that don’t improve with rest.

At-home iron testing options

There are also a number of at-home testing options available, some of which even include the option to consult with a nurse if your iron levels are found to be abnormal, so you can start feeling better, faster.

How to treat iron deficiency from heavy periods

Fortunately, iron deficiency can be easily treated, and many women report feeling better within a few weeks of treatment! If you are found to be iron-deficient, your doctor might offer a number of treatment options, including diet changes and medication.

Do iron supplements make your period heavier?

No, iron supplements don’t make your period heavier. In fact, they often help your cycle feel more balanced by restoring the iron your body loses through bleeding.

Iron supports healthy blood vessel constriction, which can actually help regulate flow. According to the National Institutes of Health (NIH), supplements are safe when taken as directed, though mild side effects like constipation are common.

If your periods seem heavier after starting iron, it’s likely due to another cause, such as hormonal changes or an underlying condition. Checking in with your healthcare provider can help you get to the root of it.

Over-the-counter iron supplements

If your doctor confirms you’re low on iron, you can often start with an over-the-counter supplement. There are a few types to choose from, each with slightly different absorption rates and side effects.

The most common forms are:

• Ferrous sulfate: The standard, widely available option and often the most affordable.
• Ferrous gluconate: Gentler on the stomach but slightly lower in iron content.
• Iron bisglycinate: A highly absorbable, stomach-friendly form often found in higher-end supplements.

To improve absorption, take iron with a source of vitamin C (like orange juice) and avoid pairing it with calcium, coffee, or tea, which can interfere with uptake. Generally, it’s recommended to take supplements on an empty stomach when possible, but if you experience nausea or discomfort, it’s fine to take them with food.

Some people prefer taking iron during or right after their period, when their levels are lowest, while others take it daily. What matters most is consistency.

If constipation or stomach upset becomes an issue, try switching to a gentler form, taking it with food, or reducing your dose under your doctor’s guidance. Look for supplements that include vitamin C or state “high absorption” on the label, and always check that the product is third-party tested for purity and potency.

Prescription options like ACCUFeR

Medications are highly effective treatments for iron deficiency and are often one of the first treatment options your doctor might suggest.

Medications like ACCUFeR, a twice-daily prescription that treats low iron stores in the body, have been found to restore hemoglobin stores to normal levels within 12 weeks of treatment for the majority of patients, with a third seeing results in just 4 weeks!

Dietary changes to boost iron

Changes to your diet can also be effective at treating iron deficiency, and there are plenty of iron-rich foods to suit every lifestyle and preference. These include:

• Red meat, like beef, veal, and lamb, contains heme iron, the most easily absorbed form.
• Leafy greens such as kale, spinach, and collard greens, packed with non-heme iron (best absorbed when paired with vitamin C).
• Poultry like chicken and turkey offer moderate amounts of iron and are gentle on digestion.
• Seafood, especially tuna, sardines, oysters, and clams; all rich in iron and omega-3s (tinned fish date night, anyone?)
• Iron-enriched pasta, grains, and cereals can help fill any dietary gaps.

To get the most out of your meals, pair iron-rich foods with vitamin C sources like citrus fruit, peppers, or tomatoes to enhance absorption. On the flip side, try not to combine iron-heavy meals with coffee, tea, or calcium-rich foods (like milk or cheese), as they can block absorption.

A little planning goes a long way; think of mixing spinach into a citrusy salad, adding lentils to a tomato-based stew, or enjoying steak with roasted peppers. Small, consistent choices like these can help rebuild your iron stores naturally and make your meals feel a bit more energising, too.

IV iron therapy: When it's needed

In more severe cases of iron deficiency, or when oral supplements aren’t working, your doctor may recommend IV iron therapy. This treatment delivers iron directly into your bloodstream, helping restore your levels more quickly than tablets.

It’s often used when supplements cause stomach upset, when absorption issues (like celiac disease or inflammatory bowel disease) make oral iron less effective, or when heavy bleeding keeps your levels low. According to the American Society of Hematology, IV iron can raise hemoglobin and ferritin levels within weeks, and most people tolerate it well.

If you’ve been taking iron regularly but still feel weak, dizzy, or fatigued, it might be time to ask your provider whether IV iron could help get your energy and your cycle back on track.

Preventing anemia from heavy periods

If your periods are consistently heavy, the best prevention is staying ahead of low iron before it becomes anemia. Ask your doctor to check your ferritin and hemoglobin levels regularly, especially if you often feel tired or lightheaded.

You can also support your iron stores through diet or low-dose supplements, pairing iron-rich foods with vitamin C for better absorption and avoiding coffee, tea, or calcium around meals.

Still, it’s just as important to treat the cause of heavy bleeding itself. Managing hormonal imbalances, fibroids, or thyroid issues can help stop the cycle of iron loss for good. Preventing anemia isn’t just about replacing what’s missing; it’s about getting to the root of why you’re losing it.

Other causes of heavy periods to rule out

While low iron can make bleeding heavier, it’s not always the root cause. If your periods are regularly long, painful, or unpredictable, it’s worth ruling out other conditions that can cause excessive blood loss. A comprehensive diagnosis helps ensure you’re treating the right problem, not just the symptoms.

Here are some common causes your doctor might investigate:

• Endometriosis: When tissue similar to the uterine lining grows outside the uterus, leading to painful, heavy periods and chronic pelvic pain.
• Uterine fibroids: Noncancerous growths that can cause longer, heavier bleeding, especially in your 30s and 40s.
• Polycystic ovary syndrome (PCOS): A hormonal condition that can lead to irregular cycles, skipped ovulation, and unpredictable heavy bleeding.
• Bleeding disorders: Conditions like von Willebrand disease or platelet function disorders can make it harder for your blood to clot, increasing menstrual flow.

Getting a full work-up, including blood tests, hormone checks, and possibly an ultrasound, helps pinpoint what’s driving your heavy bleeding. Once you know the cause, you and your provider can create a treatment plan that supports both your iron levels and your overall reproductive health.

Finding relief from the heavy period–iron deficiency loop

Iron deficiency can make it hard to live your life, but it doesn’t have to. Medication and lifestyle changes are available to help you manage an iron deficiency and start feeling your best again.

If your periods are heavy, or if you’ve been feeling more exhausted than usual, it’s worth knowing that iron deficiency and heavy bleeding often feed into each other. The good news? Both are highly treatable once identified. Rebuilding your iron stores can ease fatigue and brain fog, while addressing the cause of heavy bleeding can help prevent it from happening again.

You know your body better than anyone, so if something feels off, trust that instinct. Ask your healthcare provider for a blood test to check your ferritin and hemoglobin levels, and push for answers if you feel dismissed. There’s nothing “normal” about being too tired to function every month, and you deserve to feel strong, energised, and heard.