These substances, which are usually proteins, are called antigens.
They stimulate the body to produce antibodies, which weaken or destroy the invading antigens.
In some cases, when an antibody reacts with an antigen, the organic compound histamine is released from special body cells called mast cells.
It is an excess of histamine that results in allergy symptoms.
Question: What are the common allergy symptoms? A runny nose and watering or itching eyes are common to many persons who suffer each year from hay fever.
In asthma, there is wheezing; with eczema and hives there is itching, redness, and lumps.
An inflammation of the skin (contact dermatitis) may occur from wearing rubber gloves or touching a certain chemical, such as some kinds of soap.
A reaction to antibiotics, particularly penicillin, may take the form of a rash.
Question: Why are some people allergic to certain substances and others not? This is due partly to hereditary factors; some families seem to be more susceptible to allergies than others, although particular allergies are not necessarily inherited.
Emotional disturbances can also set off allergic conditions, and many physicians believe that an emotional factor may be the main factor that triggers an asthma attack.
Question: How does a physician determine the cause of an allergy? The physician usually gets a detailed history from the patient to find the most likely source of the problem and may then carry out a skin test.
A weak solution of the substances that are suspected is injected into the skin.
A read reaction indicates an allergy to that particular substance.
Sometimes a patch test is done for the same reason.
Question: What treatment can be given for an allergic reaction? If the cause of the allergic reaction is not known, a physician may prescribe antihistamine pills or corticosteroid nasal and lung sprays to control the symptoms.
Various medications, including theophyline, are used to treat asthma.
When the cause of an allergy is known, the patient can undergo desensitization with injections of the allergen known to cause the symptoms.
Beginning with a weak solution, the dose is gradually increased over a period of weeks until a strong solution is reached and the patient is possibly immune to its effects.
This process is not always successful; it is considered by some to be potentially dangerous.
Question: Are there any dangerous allergic reactions? An allergic reaction to an insect sting or antibiotic drug, such as penicillin, is potentially dangerous and can even be fatal.
A mild reaction usually causes a rash.
In a violent reaction, which is called anaphylactic shock, the patient finds breathing increasingly difficult.
This is an emergency condition, and a physician should be consulted immediately.
Fortunately, the condition is rare.