Hyposensitization or allergy desensitization is an allergy treatment that can help decrease long-term sensitivities to allergens. Also known as immunotherapy, in this the patient is gradually vaccinated sub-cutaneously against increasingly larger doses of the allergen. The purpose is to reduce the severity of the disease and/or eliminate hypersensitivity altogether.



Hyposensitization is generally recommended for people who have selective sensitivity to specific allergens.

How do hyposensitization injections work?

The injection shot formulated consists of a mixture of the various pollens, fungi spores, animal dander and dust mites to which a person is allergic. This mixture which is called an allergy extract contains no medication such as antihistamines or corticosteroids.

Using allergy test results and the patient's history, the allergist prepares a customised extract, made of one or many allergens. Since most allergic people react adversely to more than one allergen, several extracts may be prepared. Some people need only one shot each time, while others may need more than one extract mixture.

Small doses of an allergen or allergens are regularly introduced into the body so that one can develop a resistance to it. The injections lead to the development of a protective response both by increasing the suppressor T cells and by increasing the protective, or "blocking" Ig_G (Immunoglobin G) antibodies. The more tolerant the body becomes, the fewer symptoms one will show.

Immunotherapy injections work well in both children and adults.

Are hyposensitization injections safe for pregnant injections?

Immunization injections are usually safe, and can be administered to pregnant women. However, in some cases doctors advise stoppage of this course of treatment during pregnancy. Although immunotherapy does not cause malformations in the developing baby, but in the case of a rare adverse reaction to the treatment, the foetus might suffer from oxygen deprivation.

When are hyposensitization shots usually administered?

Hyposensitization injections are prescribed when:

* There is zero response to allergy medications.

* Side effects from allergy medications.

* To allergic children with hay fever and/or asthma.

* In case of allergic reactions to insect stings - immunotherapy may be given regardless of age.

* There is a need to decrease long-term use of medications, such as in a child or in a woman wanting to get pregnant.

In older patients, hyposensitization is usually not recommended as they may have a reduced capacity to cope with side-effects. Hyposensitization is effective if started at an early age, soon after the development of allergies.

How effective is hyposensitization?

About 80 to 90 percent of children improve with hyposensitization, if started at an early age. It usually takes atleast 12-18 months before concrete reduction in allergy symptoms can be noticed.

Hyposensitization treatment needs to be continued along with other allergy medications. It is also important to continue eliminating triggering allergens from the environment.

What are the advantages?

* Hyposensitization injections, taken on a regular basis help relieve asthma symptoms, especially for those prone to airborne allergies.

* Hyposensitization reduces asthma symptom severity, reduce medication use over time, improve quality of life, and even reduce the risk of developing new allergies in the future.

* These injections are not physiologically addictive.

* Hyposensitization injections are safe. They can be given to children and pregnant women. .

* A 3-5 year immunotherapy schedule may provide asthma relief for 10 to 30 years.

What are the side effects/ disadvantages of hyposensitization?

* Local reaction in the form of redness, itching and swelling at the injection site might occur. If this condition occurs repeatedly, then the strength or timing of a shot is changed.

* A systemic reaction can also evolve that involves not the place of injection, but a different site. Symptoms include nasal congestion, swollen lips, loss of bladder and/or bowel control, sneezing, swelling, wheezing, and low blood pressure. Such reactions can at times be serious and life threatening. However, deaths related to immunotherapy are rare.

* Inconvenience during the treatment stage ? hyposensitization shots are usually given every week for several months or more. This becomes quite cumbersome for those with hectic work schedules and busy lives.

* Long term treatment - depending on a person's sensitivity, one could be receiving shots for three to five years.

* Shots usually don't control food allergies and may aggravate skin allergy symptoms.

What precautionary measures are recommended in order to minimise reactions after a hyposensitization recommended:

1. The initial dose of injection extract must be customised according to each patient based on his history and skin test results. Highly sensitive patients with skin test reactivity should be started with higher levels of dilutions.

2. In very sensitive patients, it is better if an antihistaminic dose is given about an hour before injection.

3. The site of injection must be inspected for local reactions before the patient leaves.

4. The schedule dose should be modified if there is reaction to the previous injection, or there is any respiratory tract infection.