Headaches
Headaches can be caused by a variety of issues. In this case, thin blood is not carrying enough oxygen to properly nourish the cells of the brain. This leads to sudden, intense pain.
Headaches are a sign that the iron deficiency has become extreme. The body sends oxygen to the brain preferentially because we cannot live without it. By the time the brain is affected, the deficiency is likely severe. New headaches are a red flag requiring a visit to the doctor regardless of the cause.
