If some breaks out in a rash or is made to sneeze by such things as dust, animal fur, or pollen, then that person has an allergy. To have an allergy means to be affected by something which is harmless to most people. The substance causing the allergic reaction is called an allergen. People can be allergic to all sorts of things, including certain foods.
It is not at all clear why some people have allergies while others do not. Many doctors and scientists think that heredity has a part in deciding who will be allergic, there are families in which grandparents, parents, and children are all allergic to the same substance. However, in many other cases of allergy, no other member of the family has been allergic. Doctors do know something about how the body behaves when in contact with the substance which starts the attack.
For example, suppose a child is allergic to chocolate. The first time he or she eats chocolate, it is digested in the stomach and intestines. The digested chocolate causes special cells in the tissues of the body to make a chemical called an antibody. The next time chocolate is eaten, its digestive products combine with the antibodies in the skin and lungs. This causes damage to the small blood vessels in the skin, allowing fluid to escape. As a result, little spots of fluid collect on the skin, appearing as hives (spots or blotches). The effects on the lungs may be a pouring out of thick mucus and the closing down of the bronchial tubes. This is asthma. During the attack, the child has great difficulty in breathing.
Antibiotics, in general, are among the body’s main defenses against infection. Only certain antibiotics cause harm in this way. When this special kind of antibody combines with the allergen (in this case, chocolate), a substance called histamine is released. The histamine then causes the allergic reaction. Certain drugs, called antihistamine drugs, can prevent the allergic reaction, though they cannot cure the allergy.
Doctors are now able to identify the substances (allergens) which cause allergies in particular people by using the scratch test. Scratches are made in a row along a person’s arm, and very small amount of material which could be the cause- such as pollen, house dust, and cat fur are placed in the scratches. If the skin around a certain scratch swells and reddens, this indicates that the patient is allergic to the substance contained in that particular scratch.
Below are four of the common allergies:
This is the name given to an allergy that many people develop, usually in early summer. Symptoms include sneezing, running eyes, coughing and headaches. This allergy was first called hay fever since it was thought to be caused by pollen from hay fields. But it is now known that pollen produced by any plant can cause the allergy.
In cases of hay fever, protein (and pollen is a protein) affects certain muscles or the cells of the capillary (little blood-vessel) walls. These muscles or cells are exposed to air in the air tubes (or bronchi) of the lungs, nose, throat, and eyes, and are likely to come into contact with pollens from several different plants.
The best way to prevent hay fever is to keep away from the kind of plant or substance that causes it. However, if attacks occur, most patients can be cured or greatly helped by injections of pollen or protein extracts. Antihistamine drugs in pill form are a temporary relief, although not a cure.
The Greek word “asthma” was adopted for this allergy. It means “panting for breath”, which is what we all do after running or exercising hard. But the panting described by doctors as asthma comes in bouts, or “attacks”, lasting anything from a few minutes to an hour or two, and may even start when a person is sleeping. Instead of taking great gulps of air, like a runner, the asthmatic has to struggle for breath. Bubbling and wheezings can be heard in the chest as an asthmatic breathes because the air has to be sucked and blown through air tubes that are almost blocked.
Asthmatics have oversensitive cells in their air tubes. They are most open sensitive to house dust, feathers in pillows, and dandruff from animals, grass pollen, the germs left behind after cold and sore throats, and even chemical irritants in the air. The air tubes, or bronchi, leading from the windpipe into the lungs have circular muscle fibers embedded in their walls so that they can open and shut rather as lips do when one whistle. In an asthmatics attack, the skin that lines the air tubes swells and sticky mucus ooze from it. More seriously, the tubes close up tightly, like leg muscles in cramp. Some asthmatic attacks may last only a few minutes; others may continue for several days.
Asthmatic attacks usually begin in childhood, become less frequent over the years, and in about half the childhood cases disappear before adulthood.
The best way to help an asthmatic person is to stay calm when he or she suffers an attack. Sooner or later the tubes will open, and the sticky phlegm will be coughed up, and normal breathing will resume. Between attacks, most asthmatics look and feel quite well.
This is a common skin complaint, and it causes itching. In people who are nervous and easily upset, eczema may be brought on by worry and mental stress. This form of eczema is difficult to treat. Others may develop eczema through sensitivity to a particular substance in contact with the skin, or to a particular food. Substances that often bring on eczema are certain cosmetics, cheap dyes for clothes and hair, hard water, chemicals and detergents used in the home, dirt, and soap and scouring powders. This type of eczema can usually be treated once it has been established that substance is causing it. In children, eczema and asthma are often associated.
Nettle rash is another name for a complaint called urticaria (known as hives in the United States). It is an allergy to a drug or to certain foods, such as shellfish, strawberries, or eggs. It often appears quickly after some redness of the skin, lasts for anything from a few minutes to hours or even days, and then just as suddenly disappears. Some relief can be obtained by bathing the rash with soda and warm water.