What Are the Symptoms of Iron Deficiency in Women?

Iron deficiency is the most common nutritional deficiency in the world, and women of reproductive age are its primary targets — heavy periods, pregnancy, and breastfeeding all drain iron stores, while diets often don’t replace enough. Yet it’s routinely missed, because the hallmark symptom (tiredness) is also the hallmark of modern life. I spent a year blaming my exhaustion on work before a routine blood test showed ferritin levels in single digits. Wondering “what are the symptoms of iron deficiency in women”? You’re not alone — and the real answer is more straightforward than most guides make it sound.

If you’re constantly tired despite decent sleep, this article is for you. Here’s how to recognise iron deficiency, why women are especially vulnerable, how it’s diagnosed, and what treatment actually involves — including the supplement mistakes that waste everyone’s time.

The symptoms: more than just tiredness

Fatigue is the headline, but it’s a specific kind: a heavy, physical exhaustion that sleep doesn’t fix, where climbing stairs feels disproportionate and concentration crumbles by afternoon. Beyond tiredness, the symptom list is long and varied: pale skin (check inside your lower eyelids — they should be pinkish-red, not pale), shortness of breath on mild exertion, heart palpitations, headaches and dizziness, cold hands and feet, brittle nails or spoon-shaped nails (koilonychia), hair shedding more than usual, restless legs (especially in the evening), strange cravings for non-food items like ice, clay, or starch (pica — a classic and under-recognised sign), mouth ulcers or cracks at the corners of the mouth, and difficulty exercising at your normal level.

The tricky part is that these develop gradually — you normalise them. “I’m just someone who’s always cold.” “My hair’s always been thin.” Many women only recognise the symptoms in retrospect, after treatment, when they realise how long they’d been running on empty. If several items on this list sound familiar, it’s worth a blood test rather than another year of wondering.

Children, teenagers, and pregnant women have their own patterns: in pregnancy, iron needs soar (you’re building an entire blood supply for two), and deficiency is linked to premature birth and low birth weight — which is why iron is checked routinely in antenatal care. Teenage girls with newly heavy periods are another commonly missed group.

Why women are more vulnerable

The maths is straightforward: menstruation loses iron monthly (heavy periods — changing protection every hour or two, clots, periods over seven days — are the commonest cause of deficiency in premenopausal women), pregnancy and breastfeeding demand extra, and many women eat less red meat than men. Endurance athletes, vegetarians/vegans without planned iron sources, frequent blood donors, and anyone with undiagnosed coeliac disease (which impairs absorption) are at higher risk.

Gut conditions matter more than people realise: coeliac disease, inflammatory bowel disease, and even H. pylori infection can cause iron deficiency through poor absorption or chronic blood loss. This is why new iron deficiency in men or postmenopausal women triggers investigation for gastrointestinal causes — including bowel cancer screening. In premenopausal women, periods are the usual suspect, but persistent deficiency despite treatment deserves the same thorough look.

Worth knowing: heavy periods are treatable. Too many women accept flooding as normal — it isn’t. Tranexamic acid, hormonal options (including the hormonal coil, which often dramatically reduces bleeding), and iron infusions for severe cases have transformed this. If periods are driving your deficiency, treating the bleeding matters as much as replacing the iron.

Heavy periods: the commonest cause — and treatable in its own right
Pregnancy/breastfeeding: needs increase substantially
Low dietary intake: vegetarians/vegans need planned iron sources
Gut issues: coeliac, IBD, H. pylori impair absorption
In men/postmenopausal women: always investigate GI causes

Diagnosis: which tests and what the numbers mean

The key blood tests: ferritin (your iron stores — the most sensitive early marker), haemoglobin (low means anaemia has developed), and often transferrin saturation and serum iron. Important nuance: you can be iron deficient without being anaemic. Low ferritin with normal haemoglobin still causes fatigue, hair loss, and restless legs — and it’s frequently dismissed because “your blood count is normal.” If you’re symptomatic with low ferritin, push for treatment, not reassurance.

Ferritin interpretation has traps: it’s raised by inflammation, so a “normal” ferritin during illness can mask deficiency; and lab reference ranges are wide (often 15–300 μg/L), with many clinicians treating below 30 μg/L as deficient in symptomatic people, even though the lab flags only below 15. Ask for your actual numbers, not just “normal/abnormal.”

You can get these tests via your GP (free, though you may need to advocate for ferritin specifically, not just a full blood count) or privately — iron studies typically cost £29–£49 as part of a private blood test. Retest 3 months after starting treatment to confirm it’s working.

Treatment: supplements done right

First-line treatment is oral iron tablets — usually ferrous fumarate or ferrous sulfate, one daily. The mistakes that make them “not work”: taking them with tea/coffee or calcium (which block absorption — take iron on an empty stomach or with vitamin C, an hour from tea), taking them sporadically (daily for at least three months is needed to rebuild stores), and giving up because of side effects. Constipation, nausea, and dark stools are common; taking the tablet every other day actually improves absorption and reduces side effects (counterintuitive but well-evidenced), as does trying a different formulation.

Dietary iron helps but rarely fixes established deficiency alone: haem iron (red meat, liver, oily fish) absorbs far better than non-haem iron (lentils, spinach, fortified cereals). Pair plant iron with vitamin C (peppers, citrus, tomatoes) to boost absorption two to threefold. Cooking in cast iron adds small amounts. But be realistic: food maintains, supplements restore.

If tablets aren’t tolerated or ferritin won’t budge, iron infusions (IV iron) are available — via GP referral for severe cases, or privately (£200–£500). They work fast and bypass gut side effects entirely. And crucially: treat the cause. Iron tablets without addressing heavy periods or coeliac disease is bailing water without fixing the leak. For general immune and energy support alongside, see boosting immunity during flu season.