Hives are raised, itchy welts on the surface of the skin caused by hypersensitivity to a substance. When the body encounters a substance that it is allergic or sensitive to, it releases histamines and other chemicals into the bloodstream. As a result, the capillaries and tiny veins leak. The leaking fluid gets trapped in the skin and lining membranes, which causes the localized swelling seen with hives. The welts, which are also called wheals, may remain small, or may spread large enough to join together. With hives, the center of the welt blanches, or turns white, when pressed.
When hives occur around the face, particularly around the lips and eyes, they are called angioedema. Angioedema may also occur on the hands, feet and throat. Hives can come and go suddenly, often without any apparent cause. It is estimated that up to 70% of hives go undiagnosed as to the cause, because they can appear hours after exposure to the irritant.
Up to 20% of people will have hives at some point in their lives, but surprisingly, girls are more prone to hives than boys. Family history also plays a part in determining whether a person is inclined to developing hives. If you have a genetic tendency to allergies or food sensitivities, chances are that you may develop hives sometime.
Hives are a manifestation of an inflammatory response of the body. Substances which trigger hives can come from many different sources. Common triggers include medicine, food, contact irritants, infection or illness, environment and stress.
Medicines, such as antibiotics, often trigger hives. Food such as shellfish, fish, eggs, milk, nuts, berries and food additives are the most common histamine triggers. Some contact irritants which can bring on a reaction include animal dander, moth scales, animal saliva and insect bites and stings.
Inhaled irritants also can cause hives — this is often common with people who suffer from hay fever. Mold and pollen are other inhaled allergens that may cause hives. Illnesses, infections and parasites such as mononucleosis, strep and giardia can cause an inflammatory response as well.
There are several other physical causes of hives, or uticaria, as doctors call them. These include cold uticaria, which are hives caused by contact with cold water or air. Dermatographia is a more rare cause of hives, affecting only 5% of people. People who suffer from dermatographia get hives by simply rubbing or stroking their skin.
Pressure uticaria is caused by tight clothing or jewelry. Heat, exercise or emotional stress can cause cholinergic uticaria. Aquagenic uticaria results from exposure to sweat and water. One of the rarest forms of hives is solar uticaria, which is caused by exposure to the sun.
Although hives can vary as to how itchy they are, they are usually uncomfortable to experience. Hives are harmless, but they can indicate a serious allergy or underlying illness. Chronic uticaria should be investigated by your physician.
Complications of hives can include anaphylaxis, which is a swollen airway. This can be the result of a serious allergy and should be treated immediately. Symptoms of a serious reaction include tightness in the throat, shortness of breath, swelling of the tongue or face, wheezing and loss of consciousness.
Home treatments for hives include over the counter anti-itch cream and antihistamines. For those who seek the treatment of a doctor, Atarax, a more powerful antihistamine, may be prescribed. Newer antihistamines with H2 blockers have proved useful in the treatment of allergies and the resulting hives.
What causes urticaria (hives) is more difficult to answer than what happens during urticaria. In almost half the cases we know what causes or induces urticaria; and half the time, the patients or we have no clue as to its exact causation. It must be noted that Urticaria is not always allergic in nature. There are allergic and non-allergic causes for chronic urticaria. The non-allergic causes include auto-immunity related, hormonally triggered, stress triggered, exercise and temperature based and other factors.
We shall try to examine some of the most common exciting factors known to induce urticaria (hives), which may be grouped as:
A large number of allergens have been identified as causative agents for some cases of urticaria. It may be noted that urticaria is an individual hypersensitivity and the following factors may not cause urticaria in all urticaria-prone individuals.
Milk, cheese, egg, protein products, wheat, cereals, certain daals as used in India, peas, orange, fish, chicken, etc. Synthetic and natural food additives and artificially-flavored food articles.
True anaphylactic reactions to alcohol (ethanol) are rare and most reactions to ingested alcoholic beverages are secondary to other chemicals in the beverage such as metabisulfite, papain, dyes or yeasts. However, there are reports of true allergic reactions in which the offending agent was shown to be the ethanol itself. Generally the symptoms of anaphylaxis occur in such patients following the ingestion of beer and/or wine. Urticaria rashes have been reported with ethanol ingestion; and hives on contact with ethanol have also been reported for some patients.
Exposure to pollen, house-dust, buffalo dander, fungi, change in temperature, etc. are known exciting factors. Extreme cold, heat, pressure may also induce urticaria.
The major cause for urticaria are man-made drugs such as antibiotics (Penicillin), NSAIDs, anti-inflammatory drugs (aspirin, indomethacin), vaccinations, foreign sera, hormonal preparations, etc. Animals treated with penicillin excrete a small amount of it in the milk sufficient to cause urticaria in sensitive individuals.
There have been reports of morphine-induced hives in some people. Bronchospasm may occur in some people who smoke cocaine or in those who inject heroin. This may occur more often in those who have a previous history of asthma. Hypersensitivity pneumonitis to cocaine has also been described and is associated with elevated levels of IgE.
Insect bites, Fungal, protozoal, frequent bacterial infections (Urinary tract), viral infections (Hepatitis), helminthiasis (worm infestations such as round worms, tapeworms), etc. are factors known to cause urticaria. Domestic contact with the pet animals should be examined as cause for urticaria.
Use of products such as deodorant, perfume, and talcum powder, cosmetic products, animal derivatives, and similar synthetic substances may induce this disorder.
Especially in chronic, recurring cases of urticaria the role of emotional factors must be examined. Emotional stresses may directly or indirectly make on susceptible to develop a tendency to urticaria. The psychological factors may work as exciting, aggravating or maintaining cause.
Chronic urticaria is now understood to have autoimmune link. Presence of auto antibodies against Immunoglobulin E (IgE), CD23 (FcεRII or Fc epsilon RII) which releases histamine, hence leading to chronic urticaria.
Urticaria in some cases may present as a sign of other systemic or general internal disease such as hormonal disorders (hyperthyroidism), SLE, polycythaemia, reticuloses, etc. In certain variety of malignancies (cancer) urticaria may present as a precursor.
No list of causation is complete without adding a paragraph of 'Idiopathic' which simply implies causes which are unknown.
The goal of treating most cases of ordinary urticaria is to relieve symptoms while the condition goes away by itself. The most commonly used oral treatments are antihistamines, which help oppose the effects of the histamine leaked by mast cells. The main side effect of antihistamines is drowsiness.
Many antihistamines are available without prescription. Some of these can be taken up to three times a day, but because these medications can cause drowsiness, they are often taken at bedtime. Those who take them should be especially careful and be sure they are fully alert before driving or participating in other activities requiring mental concentration. Read the fact sheet that comes with these medications.
Loratadine (Claritin, 10 milligrams) is an antihistamine available over the counter that is less likely to cause drowsiness.
Antihistamines that require a prescription include cyproheptadine (Periactin), which tends to cause drowsiness. Prescription antihistamines that cause little sedation are fexofenadine (Allegra) and levocetirizine (Xyzal). Sometimes physicians combine these with other types of antihistamines called H2 blockers, such as ranitidine (Zantac) and cimetidine (Tagamet). This antihistamine list is not exhaustive. Physicians individualize treatment plans to suit specific patients and modify them depending on the clinical response.
Oral steroids can help severe cases of hives in the short term, but their usefulness is limited by the fact that many cases of hives last too long for steroid use to be continued safely. Other treatments have been used for urticaria as well, including montelukast (Singulair), ultraviolet radiation, antifungal antibiotics, agents that suppress the immune system, and tricyclic antidepressants. Evidence to support the benefit of such treatments is sparse. In ordinary cases, they are rarely needed.
Topical therapies for hives are available but are generally ineffective. They include creams and lotions which help numb nerve endings and reduce itching. Some ingredients which can accomplish this are camphor, menthol, diphenhydramine, and pramoxine. Many of these topical preparations require no prescription. Cortisone-containing creams (steroids), even strong ones requiring a prescription, are not very helpful in controlling the itch of hives.