Hay Fever

Hay Fever, form of seasonal rhinitis caused by allergy to pollens. Its symptoms are intense seizures of sneezing; inflammation of nose and eye membranes; and wheezing. Hay fever occurs annually at the same season. It is a reaction to inhalation of airborne pollens to which an individual is sensitive. Persons with a family history of hay fever may inherit a tendency to react, not to specific allergens, but to those to which they are exposed.

A doctor may determine the sensitizing agent or agents by scratching the skin of the patient and applying various pollens. The pollens to which the patient is allergic will produce a wheal-and-flare reaction. Because hay fever involves an antigen-antibody reaction in which histamine in the body is released and irritates blood vessels and glands, some anti-histaminic agents may furnish relief. Long-term therapy involves a series of injections of pollen extracts before the pollen season begins; repeated annually, these relieve 75 percent of cases.

Treatment: Antihistamine such as Astemizole and Fexofenadine; Steroids such as Beclomethasone Dipropionate and Triamcinolone

Cold, Common

Common Cold, acute infectious disease of the upper respiratory tract, caused by more than 100 kinds of viruses. The infection affects the mucous membranes of the nose and throat, causing such symptoms as nasal congestion and discharge, sore throat, and coughing. These symptoms are typical also of respiratory infections caused by bacteria, and of allergic conditions such as hay fever and asthma; therefore, the common cold is difficult to diagnose with certainty.

Normally it runs a mild course, without fever, and subsides spontaneously in about seven days. Its medical significance lies in the possible complications that may ensue. Various diseases, such as bronchitis, pneumonia, and sinus or middle-ear infections, may arise from the cold. Research indicates that there are several strains of each type of virus with varying degrees of virulence. Infection with one strain confers only a brief immunity to reinfection by the same strain, and gives no immunity against the other strains. In 1985, United States researchers using advanced X-ray crystallography techniques produced a three-dimensional, atomic scale model of one of the most common cold viruses. Study of the antibody binding sites on the viral coat revealed a very high degree of antigenic variability, suggesting that production of a vaccine to protect people from the common cold may never be practical.

Methods of treating a cold are directed toward the relief of symptoms and the prevention of complications. Bed rest is commonly recommended to avoid complications, even when the cold itself is not incapacitating. Antibiotics are often administered as a preventive measure, but there is no evidence that they are helpful.

related articles:

• influenza
• virus

Antihistamine

Antihistamine is any drug that blocks the action of histamine. Antihistamines are used primarily to control symptoms of allergic conditions such as hay fever. They alleviate runny nose and sneezing and, to a lesser extent, minimize conjunctivitis and breathing difficulties. Antihistamines can also alleviate itching and rash caused by food allergy. Chemically, antihistamines comprise several classes, and a person who does not obtain relief from one type may benefit from another. Side effects of these drugs can include drowsiness, loss of concentration, and dizziness. People taking antihistamines should not drink alcoholic beverages or perform tasks requiring mental alertness, such as driving. A few antihistamines, such as terfenadine and astemizole, are nonsedating. Although antihistamines are included in many over-the-counter cold remedies, their usefulness in such preparations is questionable. Antihistamines may relieve symptoms of allergy accompanying a cold, or they may have an anticholinergic effect that dries cold secretions, but they do not have any influence on viral infections, which are the cause of colds. Moreover, the drying effect may be undesirable, especially for persons with bronchial infection, glaucoma, or urinary tract difficulties.

Barbiturate

Barbiturate, any of an important group of drugs that depress brain function; they are derived from barbituric acid (C4H4N2O3), a combination of urea and malonic acid. Depending on the dosage or formulation, barbiturates have a sedative (tranquilizing), hypnotic (sleep-inducing), anticonvulsant, or anesthetic effect. Very short-acting barbiturates such as thiopental are injected intravenously to induce rapid anesthesia before surgery. Phenobarbital, a long-acting barbiturate, is prescribed with other medications to prevent epileptic seizures. Other barbituric-acid derivatives, such as secobarbital, were used as antianxiety medications until the development of the tranquilizer; they are still in use for the short-term treatment of insomnia, although tranquilizers are more suitable sleep inducers. Barbiturates are common drugs of abuse. Taken orally or intravenously, they produce symptoms similar to drunkenness: loss of inhibition, boisterous or violent behavior, muscle incoordination, depression, and sedation. They are physically addicting and produce severe withdrawal symptoms; overdoses can cause profound shock, coma, or death. See Drug Dependence.

Anxiety

Anxiety, emotional state in which people feel uneasy, apprehensive, or fearful. People usually experience anxiety about events they cannot control or predict, or about events that seem threatening or dangerous. For example, students taking an important test may feel anxious because they cannot predict the test questions or feel certain of a good grade. People often use the words fear and anxiety to describe the same thing. Fear also describes a reaction to immediate danger characterized by a strong desire to escape the situation.

The physical symptoms of anxiety reflect a chronic “readiness” to deal with some future threat. These symptoms may include fidgeting, muscle tension, sleeping problems, and headaches. Higher levels of anxiety may produce such symptoms as rapid heartbeat, sweating, increased blood pressure, nausea, and dizziness.

Anxiety disorders include generalized anxiety disorder, phobias, panic disorder, obsessive-compulsive disorder, and post-traumatic stress disorder.

Most anxiety disorders do not have an obvious cause. They result from a combination of biological, psychological, and social factors.