Iron Deficiency in Women: Why It's So Common and What to Do About It

Why Women Are More Vulnerable

Iron deficiency is the most common nutritional deficiency in the world, and women bear the brunt of it. The main reason is menstruation. Every month, women lose iron through their period, and if those losses are on the heavier side, it's easy for the body to fall behind even with a reasonable diet.

Pregnancy increases iron needs significantly, and the postpartum period can leave stores depleted for months or even years. Women who exercise a lot, follow a vegetarian or vegan diet, or have gut conditions that affect absorption are also at higher risk. It's rarely one single cause; it's usually a combination of factors quietly draining reserves over time.

What It Actually Feels Like

The classic symptom is fatigue: not just tiredness, but a bone-deep exhaustion that doesn't improve with rest. Many women describe feeling like they're wading through mud. Concentration suffers, memory feels unreliable, and motivation drops. Because these symptoms are so non-specific, they're easy to dismiss.

Beyond fatigue, low iron can cause breathlessness on exertion, heart palpitations, headaches, and dizziness. Some women notice their hair thinning or shedding more than usual. Restless legs, an uncomfortable urge to move your legs especially at night, is another symptom that's strongly linked to iron deficiency and is often not recognised as such.

Pale skin, brittle nails, and a sore tongue are classic signs too, though these tend to appear with more severe or long-standing deficiency.

Iron Deficiency vs Iron Deficiency Anaemia

These are not the same thing, and the distinction matters. Anaemia means your red blood cells are affected and your haemoglobin is low. Iron deficiency can cause anaemia, but your iron stores can be depleted well before your haemoglobin drops.

This is why a standard full blood count alone can miss the problem. The key test is ferritin, which measures your stored iron. I regularly see women with a normal haemoglobin but a ferritin so low that their body simply doesn't have enough iron to function well. They've often been told their blood test was fine. It wasn't the whole picture.

What the Numbers Mean

Laboratory reference ranges for ferritin are wide, and the lower end is often set too low to reflect optimal function. A ferritin of 12 µg/L is technically within range at many labs, but many women feel significantly better when their levels are above 50, and some need to be higher still to feel well.

When I'm investigating fatigue or hair loss, I look at ferritin alongside a full blood count, transferrin saturation, and sometimes other markers depending on the picture. I also want to understand why the iron is low, not just that it is.

Fixing the Cause, Not Just the Number

Treating low iron properly means understanding where it's going. If heavy periods are the reason, addressing the menstrual bleeding, whether through hormonal options, an IUD, or investigating for underlying causes like fibroids or endometriosis, is as important as taking iron supplements.

If diet is a factor, I'll talk through practical ways to improve iron intake. Haem iron from red meat, chicken, and fish is absorbed much more efficiently than non-haem iron from plant sources. Vitamin C taken alongside plant-based iron boosts absorption. Tea, coffee, and calcium-rich foods can inhibit it when consumed at the same time.

If there's a gut issue reducing absorption, such as coeliac disease, inflammatory bowel disease, or previous gut surgery, that needs to be part of the conversation too.

Supplements and Iron Infusions

Oral iron supplements are effective but can cause nausea, constipation, and stomach cramping. Taking them every second day rather than daily often reduces side effects without significantly reducing efficacy. They need to be taken consistently for several months to replenish stores, not just until you feel better.

For women who can't tolerate oral iron, have ongoing losses that supplements can't keep up with, or need their levels restored quickly (after a heavy postpartum bleed, for example), an iron infusion is a good option. It's done in a clinic setting and delivers iron directly into the bloodstream. Most women feel noticeably better within a week or two.

Don't Just Assume It's Stress

I want to say this directly because I see it constantly: persistent fatigue, brain fog, and low mood in women are not always just about how busy life is. They deserve to be properly investigated. Iron is one of the first things I check, and it's one of the most reliably treatable. If you've been feeling flat for months and putting it down to everything else in your life, it's worth a blood test.