For medical purposes, desensitization is a method to reduce or eliminate an organism's negative reaction to a substance or stimulus.
In pharmacology, desensitization is the loss of responsiveness to the continuing or increasing dose of a drug. It is also called tachyphylaxis, downregulation, fade or drug tolerance. This may be an important area to consider for the future design of safer drugs.
Application to allergies
For example, if a person with diabetes mellitus has a bad allergic reaction to taking a full dose of beef insulin, the person is given a very small amount of the insulin at first, so small that the person has no adverse reaction or very limited symptoms as a result. Over a period of time, larger doses are given until the person is taking the full dose. This is one way to help the body get used to the full dose, and to avoid having the allergic reaction to beef-origin insulin.
At the cellular level, administration of small doses of toxin produces an IgG response which eventually overrides the hypersensitive IgE response. A different mechanism is responsible for desensitization to antibiotics, which is performed over a shorter time course than desensitization to other allergies. In this form of desensitization, the patient is slowly exposed to a level of antibiotic that produces low-grade anaphylaxis. At the end of the procedure, the patient's mast cells have depleted their granular contents, and the patient cannot undergo any allergic response until these cells restore these contents.
- oral immunotherapy, which involves building up tolerance by eating a small amount of (usually baked) food;
- sublingual immunotherapy, which involves placing a small drop of milk or egg white under the tongue;
- epicutaneous immunotherapy, which injects the allergic food under the skin;
- monoclonal anti-IgE antibodies, which non-specifically reduce the body's capacity to produce an allergic reaction; and
- a Chinese herbal formulation, FAHF-2, another non-specific approach currently being studied in peanut allergy;
- use of probiotics;
- helminthic therapy;
- a drug to suppress Toll-like receptor 9 (TLR9); and
- mepolizumab to treat eosinophilic esophagitis.