Why does anaemia cause shortness of breath?

Oxygen enters the lungs, then haemoglobin carries it in red blood cells to the body. In anaemia, there is less oxygen-carrying capacity. Climbing stairs, walking quickly or carrying shopping can therefore bring on breathlessness sooner because the body tries to compensate by breathing faster and increasing circulation.

Shortness of Breath is a very common presentation of Anaemia. Breathlessness also has causes involving the lungs, heart, infection, anxiety and physical deconditioning. Its cause cannot be judged from the sensation alone, particularly when it is new, worsening or occurs at rest.

Book a clinical review for ongoing breathlessness, especially if it is limiting normal activity or comes with fatigue, weakness, pallor, dizziness or palpitations. The assessment may include questions about bleeding, menstrual periods, diet, medical conditions and medicines, together with a blood test and other checks where indicated.

Reduce exertion to a comfortable level until you have been assessed, but do not assume breathlessness is due to anaemia. Keep track of whether it appears with activity, while lying flat, during the night or at rest, as this information can be useful at an appointment.

Seek urgent medical care for severe or sudden breathlessness, breathlessness at rest, chest pain, blue or grey lips, fainting, confusion, or difficulty speaking in full sentences. Urgent help is also needed if you have symptoms of substantial bleeding, such as black stools, vomiting blood or heavy bleeding.

Ask whether anaemia could be contributing to your breathlessness, what tests are needed, and whether your heart or lungs also need evaluation. Ask what level of activity is appropriate while the cause is being investigated.