Can you be allergic to a disease?

You cannot be allergic to a disease. An allergy is a reaction by the body's immune system to a foreign substance, such as pollen, dust, or certain foods. Diseases, on the other hand, are caused by microorganisms such as bacteria, viruses, or fungi, or by genetic defects. Your immune system is designed to defend against invading pathogens and does not mistake diseases for foreign substances. When you have a disease, your body's immune response is not specifically targeted at the disease, but rather at eliminating the causative agent, such as a virus or a bacterial infection.