What causes allergy?What is the best way to alleviate allergic reactions?

Question

I have a friend who experiences ithcy feeling on her skin n when she scratches it swells a lot

Answer 1

Allergy is a local or systemic inflammatory response to allergens. Local symptoms are:

* Nose: swelling of the nasal mucosa (allergic rhinitis)
* Eyes: redness and itching of the conjunctiva (allergic conjunctivitis)
* Airways: bronchoconstriction, wheezing and dyspnoea, sometimes outright attacks of asthma, in severe cases the airway constricts due to swelling known as anaphylaxis.
* Ears: feeling of fullness, possibly pain, and impaired hearing due to the lack of eustachian tube drainage.
* Skin: various rashes, such as eczema, hives (urticaria) and contact dermatitis.
* Head: while not as common, headaches are seen in some with environmental or chemical allergies.

Systemic allergic response is also called anaphylaxis; multiple systems can be affected including the digestive system, the respiratory system, and the circulatory system. Depending of the rate of severity, it can cause cutaneous reactions, bronchoconstriction, edema, hypotension, coma and even death. This type of reaction can be triggered suddenly or the onset can be delayed. The severity of this type of allergic response often requires injections of epinephrine, sometimes through a device known as the Epi-Pen auto-injector. The nature of anaphylaxis is such that the reaction can seemingly be subsiding, but may recur throughout a prolonged period of time.

Hay fever is one example of an exceedingly common[citation needed] minor allergy — large percentages of the population suffer from hayfever symptoms in response to airborne pollen. Asthmatics are often allergic to dust mites. Apart from ambient allergens, allergic reactions can be result from foods, insect stings and reactions to medications.

Basis and cause

The exact cause of the IgE malfunctions that result in allergic reactions are not always apparent[citation needed], however, and several arguments[attribution needed] from genetic-basis, environmental-basis and intermediate proponents exist with varying validity and acceptance.

[edit] Genetic basis

There is much evidence[citation needed] to support the genetic basis of allergy. Allergic parents are more likely to have allergic children, and their allergies are likely to be stronger than those from non-allergic parents. However some allergies are not consistent along genealogies with parents being allergic to peanuts, but having children allergic to ragweed, or siblings not sharing the same allergens.

Ethnicity has also been shown to play a role in some allergies. Interestingly, in regard to asthma, it has been suggested[attribution needed] that different genetic loci are responsible for asthma in people of Caucasian, Hispanic, Asian, and African origins. It has also been suggested[attribution needed] that there are both general atopy genes and tissue-specific allergy genes that target the allergic response to specific mucosal tissues. Potential disease associated alleles include both coding region variation and SNPs. Caucasian people seem to have the most asthma[citation needed].

[edit] Relationship with parasites

Some recent research has also begun to show that some kinds of common parasites, such as intestinal worms (e.g. hookworms), secrete immunosuppressant chemicals into the gut wall and hence the bloodstream which prevent the body from attacking the parasite. This gives rise to a new slant on the "hygiene hypothesis" — that co-evolution of man and parasites has in the past led to an immune system that only functions correctly in the presence of the parasites. Without them, the immune system becomes unbalanced and oversensitive. Gutworms and similar parasites are present in untreated drinking water in undeveloped countries, and in developed countries until the routine chlorination and purification of drinking water supplies. This also coincides with the time period in which a significant rise in allergies has been observed.[citation needed] So far, there is only sporadic evidence to support this hypothesis — one scientist who suffered from seasonal allergic rhinitis (hayfever) infected himself with gutworms and was immediately 'cured' of his allergy with no other ill effects.[citation needed] Full clinical trials have yet to be performed however. It may be that the term 'parasite' could turn out to be inappropriate, and in fact a hitherto unsuspected symbiosis is at work

Answer 2

There are many things that cause an allergic reaction.What she has to do is see an allergist so she can be tested for different things to see what causes an allergic reaction,that way she can avoid the allergen if possible,and if not take medications to alleviate the symptoms that you mentioned.