Allergy Types: Other Allergies: Hives (Urticaria)
Hives are a skin reaction that causes red or white itchy welts. The welts vary in size and appear and fade repeatedly as the reaction runs its course.
Chronic hives are a condition in which the welts last more than six weeks or recur over months or years. Chronic hives usually aren’t life-threatening. But the condition can be very uncomfortable and interfere with sleep and daily activities.
Often, the cause of chronic hives is not clear. In some cases, chronic hives are a sign of an underlying health problem, such as thyroid disease or lupus.
You can try various treatments to relieve your symptoms. For many people, antihistamine and anti-itch medications provide relief from chronic hives.
Chronic hives are also called chronic urticaria (ur-tih-KAR-e-uh).
Urticaria can also be classified by the purported causative agent. Many different substances in the environment may cause urticaria, including medications, food and physical agents.
Drugs that have caused allergic reactions evidenced as urticaria include dextroamphetamine, aspirin, ibuprofen, penicillin, clotrimazole, trichazole, sulfonamides, anticonvulsants, cefaclor, Piracetam and antidiabetic drugs. The antidiabetic sulphonylurea glimepiride (trade name Amaryl), in particular, has been documented to induce allergic reactions manifesting as urticaria. Drug-induced urticaria has been known to have an effect on severe cardiorespiratory failure.
Infection or environmental agent
Urticaria can be a complication and symptom of a parasitic infection, such as fascioliasis (Fasciola hepatica) and ascariasis (Ascaris lumbricoides).
The rash that develops from poison ivy, poison oak, and poison sumac contact is commonly mistaken for urticaria. This rash is caused by contact with urushiol and results in a form of contact dermatitis called urushiol-induced contact dermatitis. Urushiol is spread by contact, but can be washed off with a strong grease- or oil-dissolving detergent and cool water and rubbing ointments.
Dermatographic urticaria (also known as dermatographism or “skin writing”) is marked by the appearance of weals or welts on the skin as a result of scratching or firm stroking of the skin. Seen in 4–5% of the population, it is one of the most common types of urticaria, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped.
The skin reaction usually becomes evident soon after the scratching, and disappears within 30 minutes. Dermographism is a common form of chronic hives. Dermatographism is the most common form of a subset of chronic hives, acknowledged as “physical hives”.
It stands in contrast to the linear reddening that does not itch seen in healthy people who are scratched. In most cases, the cause is unknown, although it may be preceded by a viral infection, antibiotic therapy, or emotional upset. Dermographism is diagnosed by taking a tongue blade and drawing it over the skin of the arm or back. The hives should develop within a few minutes. Unless the skin is highly sensitive and reacts continually, treatment is not needed. Taking antihistamines can reduce the response in cases that are annoying to the patient.
Pressure or delayed pressure
This type of urticaria can occur right away, precisely after a pressure stimulus or as a deferred response to sustained pressure being enforced to the skin. In the deferred form, the hives only appear after about six hours from the initial application of pressure to the skin. Under normal circumstances, these hives are not the same as those witnessed with most urticariae. Instead, the protrusion in the affected areas is typically more spread out. The hives may last from eight hours to three days. The source of the pressure on the skin can happen from tight fitted clothing, belts, clothing with tough straps, walking, leaning against an object, standing, sitting on a hard surface, etc. The areas of the body most commonly affected are the hands, feet, trunk, abdomen, buttocks, legs and face. Although this appears to be very similar to dermatographism, the cardinal difference is that the swelled skin areas do not become visible quickly and tend to last much longer. This form of the skin disease is, however, rare.
Cholinergic or stress
Cholinergic urticaria (CU) is one of the physical urticaria which is provoked during sweating events such as exercise, bathing, staying in a heated environment, or emotional stress. The hives produced are typically smaller than classic hives and are generally shorter-lasting.
Multiple subtypes have been elucidated, each of which require distinct treatment.
The cold type of urticaria is caused by exposure of the skin to extreme cold, damp and windy conditions; it occurs in two forms. The rare form is hereditary and becomes evident as hives all over the body 9 to 18 hours after cold exposure. The common form of cold urticaria demonstrates itself with the rapid onset of hives on the face, neck, or hands after exposure to cold. Cold urticaria is common and lasts for an average of five to six years. The population most affected is young adults, between 18 and 25 years old. Many people with the condition also suffer from dermographism and cholinergic urticaria.
Severe reactions can be seen with exposure to cold water; swimming in cold water is the most common cause of a severe reaction. This can cause a massive discharge of histamine, resulting in low blood pressure, fainting, shock and even loss of life. Cold urticaria is diagnosed by dabbing an ice cube against the skin of the forearm for 1 to 5 minutes. A distinct hive should develop if a patient suffers cold urticaria. This is different from the normal redness that can be seen in people without cold urticaria. Patients with cold urticaria need to learn to protect themselves from a hasty drop in body temperature. Regular antihistamines are not generally efficacious. One particular antihistamine, cyproheptadine (Periactin), has been found to be useful. The tricyclic antidepressant doxepin has also been found to be an effective blocking agent of histamine discharge. Finally, a medication named ketotifen, which keeps mast cells from discharging histamine, has also been
This form of the disease occurs on areas of the skin exposed to the sun; the condition becomes evident within minutes of exposure. After the individual is no longer exposed to the sun, though, the condition starts to weaken within a few minutes to a few hours, and hardly ever lasts longer than 24 hours. Solar urticaria is classified into six different types, depending upon the wavelength of light involved. Since glass absorbs light with a wavelength of 320 nm and below, people suffering from solar urticaria in response to wavelengths of less than 320 nm are protected by glass.
This type of urticaria is also termed rare, and occurs upon contact with water. The response is not temperature-dependent and the skin appears similar to cholinergic form of the disease. The appearance of hives is within one to 15 minutes of contact with the water, and can last from 10 minutes to two hours. The hives that last for 10 to 120 minutes do not seem to be stimulated by histamine discharge like the other physical hives. Most researchers believe this condition is actually skin sensitivity to additives in the water, such as chlorine. Water urticaria is diagnosed by dabbing tap water and distilled water to the skin and observing the gradual response. Aquagenic urticaria is treated with capsaicin (Zostrix) administered to the chafed skin. This is the same treatment used for shingles. Antihistamines are of questionable benefit in this instance, since histamine is not the causative factor.
Chizzola maculae is a very specific skin lesion due to fluoride exposure. The size of a coin, these lesions may resemble small blue bruises or be wholly pink. Doctors George Waldbott and V. A. Cecilioni named them after a town in Italy, where these lesions were common in young women and children. According to Dr. Waldbott, Chizzola maculae are early symptoms of fluoride intoxication.
The condition was first distinguished in 1980. People with exercise urticaria (EU) experience hives, itchiness, shortness of breath and low blood pressure five to 30 minutes after beginning exercise. These symptoms can progress to shock and even sudden death. Jogging is the most common exercise to cause EU, but it is not induced by a hot shower, fever, or with fretfulness. This differentiates EU from cholinergic urticaria.
EU sometimes occurs only when someone exercises within 30 minutes of eating particular foods, such as wheat or shellfish. For these individuals, exercising alone or eating the injuring food without exercising produces no symptoms. EU can be diagnosed by having the patient exercise and then observing the symptoms. This method must be used with caution and only with the appropriate resuscitative measures at hand. EU can be differentiated from cholinergic urticaria by the hot water immersion test. In this test, the patient is immersed in water at 43 °C (109.4 °F). Someone with EU will not develop hives, while a person with cholinergic urticaria will develop the characteristic small hives, especially on the neck and chest.
The immediate symptoms of this uncanny type are treated with antihistamines, epinephrine and airway support. Taking antihistamines prior to exercise may be effective.Ketotifen is acknowledged to stabilise mast cells and prevent histamine release, and has been effective in treating this hives disorder. Avoiding exercise or foods that cause the mentioned symptoms is very important. In particular circumstances, tolerance can be brought on by regular exercise, but this must be under medical supervision.
The most common food allergies in adults are shellfish and nuts. The most common food allergies in children are shellfish, nuts, eggs, wheat, and soy. One study showed Balsam of Peru, which is in many processed foods, to be the most common cause of immediate contact urticaria. A less common cause is exposure to certain bacteria, such as Streptococcus species or possibly Helicobacter pylori.
In some cases, the trigger is obvious – a person eats peanuts or shrimp, and then breaks out within a short time. Other cases require detective work by both the patient and the physician because there are many possible causes. In a few cases, the cause cannot be identified.
A single episode of hives does not usually call for extensive testing. If a food allergy is suspected, consider keeping track of what you eat. This will help you discover whether there is a link between what you’re eating and when you break out with hives.
Chronic hives should be evaluated by an allergist, who will ask about your and your family’s medical history, substances to which you are exposed at home and at work, exposure to pets or other animals and any medications you’ve taken recently. If you have been keeping a food diary, show it to your allergist.
Your allergist may want to conduct skin tests, blood tests and urine tests to identify the cause of your hives. If a specific food is the suspected trigger, your allergist may do a skin-prick test or a blood test to confirm the diagnosis; once the trigger is identified, you’ll likely be advised to avoid that food and products made from it. In rare instances, the allergist may recommend an oral food challenge – a carefully monitored test in which you’ll eat a measured amount of the suspected trigger to see if hives develop. If a medication is suspected as the trigger, your allergist can conduct similar tests, and a cautious drug challenge – similar to an oral food challenge, but with medications – may also be needed to confirm the diagnosis. Because of the possibility of anaphylaxis, a life-threatening allergic reaction, these challenge tests should be done only under strict medical supervision, with emergency medication and equipment at hand.
In cases where vasculitis may be the cause, your allergist may conduct a skin biopsy and send it to a dermatopathologist to examine under a microscope.
The cause of chronic hives is often difficult to identify.
Your doctor will likely recommend you treat your symptoms with home remedies, such as over-the-counter antihistamines. If self-care steps don’t help, talk with your doctor about finding the prescription medication or combination of drugs that works best for you.
Treat any underlying factors causing your symptoms. If your doctor can determine that your hives are caused by another condition, he or she will first try to treat that. For example, people with chronic hives and inflamed thyroid (thyroiditis) may best be helped by treating the thyroid problem.
Take nondrowsy forms of antihistamine pills. Taking antihistamines pills daily helps block the symptom-producing release of histamine. The newer forms of the drugs (second-generation antihistamines) have fewer side effects, such as drowsiness, than older antihistamines:
- Loratadine (Claritin, Alavert)
- Fexofenadine (Allegra)
- Cetirizine (Zyrtec)
- Levocetirizine (Xyzal)
- Desloratadine (Clarinex)
Take older forms of antihistamine pills. If the newer antihistamines don’t help you, your doctor may recommend you take an older form of the drug, but only before bedtime, as it can make you drowsy. Examples include:
- Hydroxyzine (Vistaril)
- Diphenhydramine (Benadryl)
- Chlorpheniramine (Chlor-Trimeton)
Check with your doctor before taking any of these medications if you are pregnant or breast-feeding, have a chronic medical condition, or are taking other medications.
Try other medications. If antihistamines alone don’t relieve your symptoms, other drugs that may help include:
- Histamine (H-2) blockers. These medications, also called H-2 receptor antagonists, may be injected or taken orally. Examples include cimetidine (Tagamet), ranitidine (Zantac), nizatidine (Axid) and famotidine (Pepcid). Side effects range from digestive problems to headache.
- Anti-inflammation medications. Oral corticosteroids, such as prednisone, can help lessen swelling, redness and itching. These usually are used only for a short time to control severe hives or angioedema because they can cause serious side effects.
Corticosteroids creams applied to the skin usually aren’t effective for chronic hives. Corticosteroids can weaken your immune system, making it easier for you to get an infection or worsening an infection you already have.
- Antidepressants. The tricyclic antidepressant doxepin (Zonalon), used in cream form, can help relieve itching. This drug may cause dizziness and drowsiness.
Ask about other options. Several medications under study show promise for people whose chronic hives resist treatment:
- An injectable asthma drug. Several studies show the drug omalizumab (Xolair) is very effective against difficult-to-treat chronic hives, without side effects. But it is more costly than other options and is not usually covered by insurance.
- Asthma drugs with antihistamines. Medications that interfere with the action of leukotriene modifiers may be helpful when used with antihistamines. Examples are montelukast (Singulair) and zafirlukast (Accolate). Side effects may include behavior and mood changes.
- Cyclosporine. The drug cyclosporine (Gengraf, Neoral, others) affects the immune system and provides relief from chronic hives. Possible side effects range from headache and nausea to an increased risk of infection and reduced kidney function.
- Tacrolimus. Similar to cyclosporine, this drug reduces the immune system response that causes hives. And it, too, may cause a range of side effects, from minor to serious.
- Mycophenolate. This immune-suppressing drug also improves hives signs and symptoms. But for pregnant women, it increases the risk of miscarriage and birth defects.
Simple changes to your lifestyle may be able to help you prevent hives from reoccurring in the future. If you have allergies and you know which substances are likely to cause an allergic reaction, your doctor will likely suggest that you avoid any possible exposure to these factors. Allergy shots are another option that may help you reduce the risk of experiencing hives again. If you have just recently had a hives outbreak, you may also want to consider avoiding wearing tight clothing or being in high-humidity areas, as this may cause another outbreak.
The following precautions may help prevent or soothe the recurring skin reactions of chronic hives:
- Wear loose, light clothing.
- Avoid scratching or using harsh soaps.
- Cool the affected area with a shower, fan, cool cloth or soothing lotion.
- Keep a diary of when and where hives occur, what you were doing, what you were eating, and so on. This may help you and your doctor identify triggers.
- Avoid known triggers, such as certain foods or additives, alcohol, pain relievers, heat, cold, exertion, and stress.
Although hives can be itchy and painful, usually they are not severe and will disappear after a period of time. According to the Mayo Clinic, each individual hive will go away in as little as 30 minutes, but could also last up to 36 days. However, be aware that as some hives go away, new ones may pop up.
If you are not experiencing a severe case of hives, they are considered to be harmless. In situations where you are having a serious allergic reaction and throat swelling may block your airway, hives can be more dangerous. Getting proper treatment in a severe case of hives is important for ideal recovery.
Chronic hives complications include:
- Difficulty breathing. When swelling occurs inside your mouth or throat, you may have difficulty breathing and pass out. Seek emergency medical care if you feel your tongue or throat swelling.
- Serious allergic reaction. Anaphylactic shock (anaphylaxis) is a serious allergic reaction involving your heart or lungs. Your bronchial tubes narrow, it’s difficult to breathe, and your blood pressure drops. You may feel dizzy, pass out or even die. Anaphylactic shock happens fast. Seek emergency medical care if you feel this type of allergic reaction coming on.
People with chronic hives may be at increased risk of developing these immune system disorders:
- Thyroid disease
- Rheumatoid arthritis
- Sjogren’s syndrome
- Celiac disease
- Type 1 diabetes