Anemia (uh-NEE-me-uh) is a condition in which your blood has a lower than normal number of red blood cells. Anemia also can occur if your red blood cells don't contain enough hemoglobin (HEE-muh-glow-bin). Hemoglobin is an iron-rich protein that gives blood its red color. This protein helps red blood cells carry oxygen from the lungs to the rest of the body. If you have anemia, your body doesn't get enough oxygen-rich blood. As a result, you may feel tired or weak.
Signs and symptoms of a drug allergy often occur within an hour after taking a drug. Less commonly, reactions can occur hours, days or weeks later. Drug allergy symptoms may include: 1  Skin rash. 2  Hives. 3  Itching. 4  Fever. 5  Swelling. 6  Shortness of breath. 7  Wheezing. 8  Runny nose.
Allergy symptoms occur when the immune system overreacts to an allergen. If there is an allergy, the immune system acts as if the allergen were dangerous, releasing a chemical called histamine that causes allergy symptoms. A reaction can be mild but may be life threatening in some cases.