The Short Answer
Iron deficiency happens when your iron stores run low, often before a standard blood test flags anaemia. Common signs include persistent fatigue, hair shedding, headaches, breathlessness on exertion, and brain fog — symptoms often mistaken for stress or poor sleep.
You’ve been tired for months. You chalk it up to a busy schedule, too many late nights, not enough time to yourself.
But what if it’s not your schedule? What if your body has been trying to tell you something — and you’ve been explaining it away?
Iron deficiency is one of the most common conditions we screen for at New Path — and it also happens to be one of the least diagnosed. Not because the symptoms are subtle, but because they’re the kind of things we’re all used to normalising.
Here are five signs that are often dismissed as lifestyle issues, but could actually point to low iron.
Key Takeaways
- Iron deficiency often develops and causes symptoms way before anaemia shows up on a standard blood test.
- The five most common but often misattributed signs are fatigue, hair shedding, frequent headaches, breathlessness, and brain fog.
- Iron deficiency is the leading medical cause of hair loss in women.
- Normal haemoglobin doesn’t rule out low iron; ferritin is the marker that shows your iron stores.
- Three or more of the above symptoms lasting more than a few months is a reason to test ferritin levels.
What are the 5 signs of iron deficiency?
1. You’re exhausted, even after a full night’s sleep
This is the most common complaint we hear at New Path, and also the most commonly dismissed: “I’m just tired.” But there’s a difference between tired-from-a-long-week and tired-even-when-you’ve-rested.
Iron is essential for producing haemoglobin, the protein in red blood cells that carries oxygen around your body. When your iron levels are low, your cells aren’t getting the oxygen they need to function. That means every system in your body is working harder than it should be. The result? An unexplained deep exhaustion that sleep doesn’t fix.
2. Your hair is thinning or falling out more than usual
Iron deficiency is the leading medical cause of hair loss in women. Most people know that stress can trigger hair shedding — fewer know that iron is equally (if not more) responsible. This kind of diffuse shedding is known medically as telogen effluvium.
When your body’s iron stores are low, it directs what’s left toward essential functions — including keeping your organs running. Hair follicles, non-essential from a survival standpoint, get deprioritised. The result is slower growth and increased shedding.
If you’ve noticed more hair in the drain, on your pillow, or when you run your fingers through it, and you can’t explain it with a recent stressor or hormonal change, it may be worthwhile checking your iron levels.
3. You get headaches more often than you used to
Frequent headaches without an obvious cause are often neurological. But before jumping to conclusions, it’s worth ruling out something much simpler: low oxygen to the brain.
When iron stores drop, haemoglobin drops with them. Less haemoglobin means less oxygen-carrying capacity. The brain is extremely sensitive to oxygen fluctuations, and when it’s not getting enough, headaches are one of its earliest warning signals.
If you find yourself reaching for paracetamol more often than you used to, especially if the headaches are dull, recurring, and don’t have an obvious trigger, it’s one more reason to check your ferritin.
4. You get breathless doing things that used to be easy
Climbing a few flights of stairs. Walking briskly to catch the bus. Carrying groceries. If any of these now leave you more breathless than you’d expect — it’s a sign your body is struggling to move oxygen around as it should.
This symptom is often the one that finally prompts people to get tested, because it’s the one that’s hardest to explain away. And yet, many people still wait months before acting on it.
You don’t have to be anaemic for this to happen. Even before iron deficiency progresses to anaemia, it can reduce your body’s oxygen-carrying capacity enough to make physical exertion noticeably harder.
5. You’re foggy, forgetful, and emotionally flat
This one is perhaps the trickiest, because brain fog and low mood have so many potential causes. But iron deficiency is a genuinely underappreciated contributor to cognitive and emotional wellbeing.
Iron is required for the production of dopamine and serotonin, which are neurotransmitters that regulate mood, motivation, and focus. When iron stores are depleted, brain function suffers. You may notice difficulty concentrating, a flat or low mood, poor memory, or a general sense of not quite being yourself.
If you’ve been struggling with any combination of these, especially alongside the other symptoms on this list, your iron levels could potentially be significantly low.
Why does iron deficiency go undiagnosed?
These symptoms are very easy to explain away. We live in a culture that treats chronic fatigue as a badge of busyness. Hair loss gets blamed on stress. Brain fog gets attributed to screens and overstimulation. Headaches get managed with painkillers.
Iron deficiency tends to develop gradually, which means the changes sneak up on you. You don’t notice the shift — you just slowly adjust your expectations of how you’re supposed to feel.
The other reason? Most standard blood tests check haemoglobin but not ferritin, which is the actual measure of your iron stores. You can have completely normal haemoglobin and still be iron deficient. Which means a routine full blood count can come back “normal” while you are already symptomatic.
When should you get tested for iron deficiency?
If you’re experiencing three or more of the symptoms on this list — especially if they’ve been going on for more than a few months — it’s worth getting your ferritin levels tested.
Iron deficiency develops gradually and that is how it tends to go unnoticed. If several of these symptoms have been present for a while, checking your ferritin specifically is the most informative first step.
Frequently Asked Questions
What are the first signs of iron deficiency?
The earliest signs are usually persistent fatigue that rest doesn’t fix, along with hair shedding, frequent headaches, breathlessness on mild exertion, and brain fog. They appear because low iron reduces the oxygen your blood can carry.
Can you be iron deficient with a normal blood test?
Yes. Most standard blood tests measure haemoglobin, which stays normal until iron stores are badly depleted. A ferritin test measures your iron stores and can flag deficiency far earlier.
Does iron deficiency cause hair loss?
Yes — low iron is the leading medical cause of hair loss in women. When ferritin is low, the body diverts iron away from non-essential hair follicles, causing shedding known as telogen effluvium.
How is iron deficiency diagnosed?
A ferritin blood test is the most informative first step. Ferritin reflects your stored iron and drops before haemoglobin, so it catches deficiency earlier than a routine full blood count. Other tests that are often included in a comprehensive iron profile, such as Serum Iron, Transferrin, Iron Saturation (TSAT) and TIBC, may also be useful in further evaluation of iron deficiency and its severity, recency and/or underlying cause(s).
Ready to check your iron?
A simple ferritin test shows what a standard blood test can miss. Our iron deficiency screen checks both ferritin and haemoglobin at just $68 nett. No fasting required, and results available in 1-2 days.
