Possible symptoms include tiredness, lack of energy, shortness of breath, paler skin, headaches and noticeable heartbeats. These symptoms have many potential causes, so they need assessment rather than self-diagnosis.[1]
This page is evidence-only information. It does not diagnose anaemia, set a target result, prescribe iron or replace individual medical assessment.
When to seek urgent help
Do not rely on a routine test for emergency symptoms
Call 999 for severe chest pain, collapse, severe breathing difficulty or a life-threatening emergency. Seek urgent NHS advice for concerning symptoms such as significant bleeding, worsening breathlessness or new symptoms that need prompt assessment.
What can cause iron deficiency anaemia?
The cause can be multifactorial. NHS guidance lists heavy periods, pregnancy, bleeding from the stomach or bowel, dietary factors and other sources of blood loss. NICE CKS also considers reduced absorption, increased demand and underlying health conditions.[1] [2]
Menstrual and pregnancy-related loss
Heavy periods and pregnancy are common contexts, but the appropriate gynaecology assessment depends on the symptoms and history.
Digestive-system blood loss
Bleeding from the stomach or bowel is one possible cause. Appropriate investigation depends on risk factors and clinical assessment.
Diet and absorption
Dietary intake, coeliac disease, other conditions and previous surgery can affect iron balance.
Other causes
Medicines, blood donation and more than one contributing factor may be relevant in some people.
Blood tests and their limits
A GP commonly uses a full blood count to assess whether the number of red blood cells is normal. Iron studies, including ferritin in an appropriate clinical context, may help assess iron stores. Ferritin can be difficult to interpret in infection or inflammation, so it should not be viewed in isolation.[1] [2]
A result can help clarify whether anaemia or iron deficiency is likely, but it cannot by itself identify why it has happened. Further tests or referral may be appropriate for some people. The clinic confirms test suitability, preparation, reporting and follow-up at booking.
Treatment is linked to the cause
NHS guidance explains that iron tablets and dietary advice are commonly used once the reason for anaemia is assessed. Clinicians may use repeat blood tests to check response. However, a treatment plan should also address the cause, such as bleeding or an absorption issue.[1]
Do not use this page to select a dose, duration or route of treatment. Individual choices, adverse-effect advice and monitoring require a clinician who knows your results and circumstances.
Frequently asked questions
Can a blood test diagnose iron deficiency anaemia?
A full blood count and iron studies can contribute to an assessment. Results are interpreted with symptoms, medical history and the laboratory’s information; they do not explain the underlying cause by themselves.
Are heavy periods a possible cause?
Yes. NHS guidance lists heavy periods and pregnancy among common causes. However, persistent or severe bleeding needs its own assessment.
Can iron deficiency have another cause?
Yes. Causes can include dietary intake, increased need, malabsorption or blood loss. Clinicians investigate the cause as well as treating a deficiency.
Should I start iron without discussing the result?
A clinician should advise on the appropriate treatment, cause assessment, monitoring and follow-up. Keep iron tablets away from children: an overdose can be fatal.
Related routes and information
References
- [1]NHS: Iron deficiency anaemia
- [2]NICE CKS: Anaemia — iron deficiency
- [3]British Society of Gastroenterology: guidelines for management of iron deficiency anaemia in adults
Sources checked 30 August 2026. This evidence-only page does not replace individual assessment, diagnosis or urgent medical care.