Why does iron deficiency anaemia cause shortness of breath?

Haemoglobin in red blood cells transports oxygen from the lungs to the rest of the body. Iron deficiency reduces haemoglobin production, so muscles may receive less oxygen when they need it most. Climbing stairs, walking quickly or carrying shopping can therefore feel unusually demanding. Shortness of Breath is a common presentation of Iron Deficiency Anaemia, but breathlessness also has lung, heart, anxiety-related and other causes that need consideration.

Arrange a healthcare review for breathlessness that is new, persistent or limiting your usual activities. A clinician can check your oxygen level, heart and lungs, and arrange blood tests if anaemia is suspected. Tell them about fatigue, paleness, palpitations, heavy periods, dietary changes, black stools or any other bleeding. Pace strenuous activity until you have been assessed and follow the treatment plan recommended for the cause of iron deficiency.

Get urgent medical care for sudden or severe breathlessness, chest pain, fainting, blue or grey lips, coughing blood, or trouble speaking in full sentences. Seek prompt assessment when breathlessness occurs at rest, wakes you from sleep, or is worsening quickly. Do not assume these symptoms are due to anaemia alone.

Ask what may be causing low iron, whether any tests besides a blood count are needed, and how long it may take for exertion to feel easier after treatment starts. Ask which symptoms should prompt an earlier review.