Hypersensitivity in medical terms means you have an immune system overreaction to a substance which can be a drug or allergen that normally wouldn't cause a response.
Hypersensitivity can lead to allergy symptoms and even tissue damage.
The types of hypersensitivity reactions include.
Type I hypersensitivity which is an immediate reaction that is mediated by IgE antibodies and is the most common type of hypersensitivity and can cause food allergies, anaphlaxis and asthma.
Type II hypersensitivity is an antibody mediated cytotoxic reaction which can cause tissue damage through inflammation, disrupted cellular function or direct cellular destruction.
Type III hypersensitivity which is an immune complex mediated reaction which can cause systemic lupus erythematosus, serum sickness and post streptococcal glomerulonephritis.
The symptoms of hypersensitivity reactions often appear in people that have been exposed to the antigen before.
The reactions with hypersensitivity can be severe and even sometimes life threatening.
If you experience any skin rash or other symptoms after you take a new medication you should talk with your doctor or a health professional.
Examples of hypersensitivity include anaphylaxis and allergic rhinoconjunctivitis.
Type II hypersensitivity reactions (ie, cytotoxic hypersensitivity reactions) involve immunoglobulin G or immunoglobulin M antibodies bound to cell surface antigens, with subsequent complement fixation.
An example is drug-induced hemolytic anemia.
Allergens that can result in a type I hypersensitivity may be harmless (i.e., pollen, mites, or foods, drugs, etc.) or more hazardous such as insect venoms.
The reaction may also be manifested in different areas of the body and may result in instances such as Nasal allergic rhinitis or hay fever.