How Anaemia Causes Fatigue
Anaemia is one of the most common causes of fatigue worldwide — affecting approximately 1.6 billion people globally. It's also one of the most reliably treatable once the type and cause are identified.
How anaemia causes fatigue
Anaemia reduces the oxygen-carrying capacity of the blood — either through fewer red blood cells, less haemoglobin per cell, or dysfunctional red blood cells. Less oxygen delivered to muscles and the brain means less ATP produced and lower energy output. The body compensates by increasing heart rate (palpitations) and breathing rate, which is itself tiring.
The fatigue of anaemia is characteristically present at rest and worsened by any physical activity. Even mild anaemia produces noticeable fatigue; severe anaemia is profoundly debilitating.
Types and causes of anaemia
Iron-deficiency anaemia is the most common type — caused by inadequate iron intake, poor absorption, or blood loss (heavy periods being the most common cause in pre-menopausal women). B12 deficiency and folate deficiency cause megaloblastic anaemia. Haemolytic anaemia (red blood cell destruction), aplastic anaemia (bone marrow failure), and anaemia of chronic disease are less common but significant.
A full blood count (FBC) identifies anaemia; further tests (ferritin, B12, folate, peripheral blood film) identify the type and guide treatment.
Treatment
Treatment depends on the cause: iron supplementation for iron deficiency, B12 supplementation or injection for B12 deficiency, folate for folate deficiency. Addressing the underlying cause (heavy periods, malabsorption, dietary inadequacy) is essential alongside supplementation.
Energy improvements are typically noticeable within 4–8 weeks of adequate supplementation for deficiency anaemias, though full correction of iron stores may take 3–6 months.
Our assessment screens for anaemia risk factors and incorporates them into your personalised fatigue analysis.
Frequently Asked Questions
What are the main symptoms of anaemia?
The main symptoms of anaemia include fatigue, weakness, pale skin, shortness of breath, and dizziness, which can worsen with physical activity.
How is anaemia diagnosed?
Anaemia is diagnosed through a full blood count (FBC), which measures red blood cell levels, and further tests like ferritin, B12, and folate levels help identify the specific type.
Can anaemia cause heart problems?
Yes, anaemia can lead to an increased heart rate and palpitations as the heart works harder to deliver oxygen, potentially leading to heart complications if left untreated.
How long does it take to recover from anaemia?
Recovery from anaemia can take 4–8 weeks to notice energy improvements with proper supplementation, but full correction of iron stores may take 3–6 months.