Iron deficiency anemia treatment: what works and how long it takes
Iron deficiency anemia treatment usually means iron tablets for about 6 months, alongside finding and treating the cause, such as heavy periods. Among women's health conditions it is common and treatable; the 6-month figure is the NHS's guidance in the UK, and in the US your doctor sets the length of the course with you.
Feeling tired and foggy has many possible causes, and low iron is one that a blood test can pick up. Iron deficiency means your body's iron stores have run low. Iron deficiency anemia (anaemia in the UK) is low iron together with a low hemoglobin on a blood count. In women it is mostly linked to periods, pregnancy and growth.
What is iron deficiency anemia, and is it the same as iron deficiency?
The two are related, and the difference shows on a blood test. Ferritin measures stored iron, and a ferritin under 30 ng/mL (30 µg/L in the UK, the same number) means low stores, per the NIH Office of Dietary Supplements. Hemoglobin (haemoglobin in the UK) on a blood count is what tells low stores apart from anemia.
Low stores are far more common than anemia. In a 2023 JAMA analysis of US females aged 12 to 21 by Weyand and colleagues, 38.6% had iron deficiency (ferritin under 25 µg/L in that study) while 6.3% had iron deficiency anemia. So a normal blood count does not rule out low iron.
In the teenage years, blood loss from periods plus rapid growth raises iron needs. In the reproductive years, iron deficiency is the most common nutrient deficiency in women, mostly from periods and pregnancy.
If you are weighing iron supplements for women, it's worth knowing whether your stores are low first. A ferritin test alongside a blood count answers that, and both are worth asking your doctor (your GP in the UK) about if your periods are heavy or you are often tired.
What does the evidence show about iron deficiency anemia treatment?
The evidence supports iron deficiency anemia treatment in two parts: iron to rebuild your stores and blood count, and attention to whatever drained your iron. The NHS names heavy periods and pregnancy as very common causes of iron deficiency anaemia, so for many women, treating heavy bleeding belongs in the plan alongside the tablets.
Iron therapy in iron deficiency anemia has been tested on different schedules. In a 2023 randomized trial of 200 adults in Scientific Reports, mean hemoglobin rose 1.36 g/dL with daily iron and 1.05 g/dL with alternate-day iron at 8 weeks. The difference was not statistically significant (p=0.47). The trial compared two schedules with each other, not iron with no treatment.
Pregnancy raises the question of iron too. About 18% of pregnant people in the US have iron deficiency, rising across the trimesters from about 6.9% to 14.3% to 28.4%, and about 5% have iron deficiency anemia, according to the 2024 USPSTF statement. The USPSTF gives a Grade I, meaning insufficient evidence, to routine screening and routine iron supplements in pregnancy. If you are pregnant or planning to be, it's worth asking your OB-GYN (your midwife or GP in the UK) whether a ferritin test and blood count make sense for you.
When periods or pregnancy do not explain low iron, doctors usually look further. The NHS describes checking for blood loss from the gut, sometimes with a stool test called a FIT test, so the treatment matches the cause.
How long do you take iron, and how often?
Six months can feel long, especially once your energy returns. Many women find it helps to think of the course as rebuilding stores, and it's worth continuing for as long as your doctor advises. Repeat blood tests show whether your numbers are recovering.
How often you take it is a choice to make with your doctor. Nausea at week 4 in the 2023 trial was reported by 10.3% of those on alternate days and 2% of those on daily iron, and nobody in either group stopped because of side effects. If iron for iron deficiency anemia upsets your stomach, it's worth telling your doctor so the plan can be adjusted. The dose is set for you individually, with your primary care doctor or OB-GYN in the US and your GP in the UK.
What did the studies show, and what did they not show?
The schedule trial showed hemoglobin rising on both daily and alternate-day iron, without a clear winner. It followed adults for 8 weeks, so it does not tell us how teenagers respond or what happens over a full course.
The 38.6% figure comes from 3,490 US people with complete data and uses a lower ferritin cutoff than the under-30 line. It shows how common low stores are at those ages, not how common they are in other age groups or in the UK. If you are reading your own result or your child's, it's worth checking which cutoff the lab uses.
The USPSTF grade is not a verdict against iron in pregnancy. It reflects trials that have not settled the question, and the US prevalence figures behind it date from 1999 to 2006.
Iron deficiency by life stage
| Stage | Figure | Why | Read more |
|---|---|---|---|
| Childhood | Iron from birth runs low by about 6 months | For parents of younger children: toddlers who drink a lot of cow's milk are at risk of iron deficiency. | What changes |
| Puberty | Ferritin under 30 µg/L means low stores | A ferritin test and blood count are worth asking for if periods are heavy or your child is often tired. | What changes |
| Reproductive years | Ferritin under 30 ng/mL means low stores | Periods and pregnancy are the main drains on iron here. A check is worth it if periods are heavy, you're tired, or you're planning a pregnancy. | What changes |
| Perimenopause | Ferritin under 30 ng/mL means low stores | Periods have not stopped yet, so the same check applies if they are heavy or you're tired. | What changes |
| Menopause | No ferritin figure set for this stage | Once periods have stopped, a low result is worth a doctor's look for another cause. | What changes |
| Postmenopause | No ferritin figure set for this stage | With periods behind you, doctors look for other sources of blood loss, such as the gut check the NHS describes. | What changes |
Guidance by country
Facts
Common questions
What is dangerously low ferritin levels?
Ferritin is read on a scale, not as pass or fail. Under 30 marks low stores, and how urgent a lower result is depends on your hemoglobin and symptoms. It's worth asking your doctor for both numbers and which cutoff your lab uses, since US labs report ng/mL and UK labs µg/L.
Is anemia and iron deficiency the same?
No. You can have low iron stores with a normal blood count, which is why it's worth asking for ferritin as well as a blood count. When both are low, the term is iron deficiency anemia, and treatment covers both.
How i treat iron deficiency anemia?
The usual order is a blood test to confirm it, iron tablets, a look at the cause, then repeat tests. Good questions for the appointment: which iron and how often, what to do about side effects, when the next blood test is, and whether your periods need treating too.
How to cure iron deficiency anemia?
Iron is paired with the cause. If heavy periods are draining your stores, treating the bleeding is what helps keep anemia from returning once the tablets finish. It's worth asking when your ferritin will be rechecked, so you can see your stores have held.
Is low ferritin a sign of cancer?
Usually something else is behind it, most often periods, pregnancy or growth. The NHS does list bowel or stomach cancer as a less common cause of iron deficiency anaemia, which is why doctors check the gut when nothing else explains a low result. Asking about that check is reasonable if you are worried.
Can heavy periods cause anemia?
Yes, and it is one of the most frequent reasons, since heavy bleeding can use up more iron than you take in. Mention both the bleeding and the tiredness at the same appointment, with your doctor or OB-GYN in the US or your GP in the UK, so both are treated together.
Next steps
A good place to start is asking for a ferritin test and a blood count, and bringing your questions about dosing, side effects and the cause to that appointment. If you are already taking iron, repeat tests show how it is going. See a doctor promptly if you have unexplained weight loss, symptoms that are getting worse, or any bleeding 12 months or more after your last period. The right plan depends on your periods, your stage of life and your results. It is not one size fits all, and you decide what fits you.
See a doctor promptly if you have
- Any bleeding 12 months or more after your last period
- Unexplained weight loss
- Symptoms that are getting worse
Sources
The guidelines and studies this page draws on.
- Iron Deficiency Anemia in Pregnant Women: Screening and Supplementation, Final Recommendation Statement, USPSTF (2024)
- Iron deficiency anaemia, NHS (n.d.)
- Prevalence of Iron Deficiency and Iron-Deficiency Anemia in US Females Aged 12-21 Years, 2003-2020 (Weyand et al., JAMA research letter), JAMA / PMC (2023)
- Alternate day versus daily oral iron for treatment of iron deficiency anemia: a randomized controlled trial, Scientific Reports / PMC (2023)
- NIH Office of Dietary Supplements: iron, calcium, iodine and vitamin D intakes, NIH Office of Dietary Supplements (n.d.)