We often find hives mentioned in discussions of allergies and illness. You might have heard someone describe “breaking out” in red, itchy hives. But what are hives, really? Is hives just another word for a rash?
Hives are a specific kind of rash. They’re characterized by several raised, red or flesh-colored bumps called wheals. These wheals can grow and swell, forming larger patches called plaques.
Hives lack the rough, scaly appearance and texture found with many other kinds of rashes.
The scientific name for hives, urticaria, was first used by Scottish physician William Cullen in 1771. It comes from the Latin word urtica, or “nettle–” which itself is derived from the Latin word urere, which means “to burn.” This is a nod to the stinging hairs on the leaves of European nettles and their uncomfortable effects on the skin.
Who Is Affected by Urticaria (hives)?
Urticaria is not an uncommon problem; one in five people worldwide will experience hives at some point in their lives. It is more common in people with allergies, and it more commonly affects women than men (although a subset of urticaria called delayed pressure urticaria more commonly affects men).
Most people will experience hives as acute urticaria; their hives will resolve within six weeks or less. Others will find that their hives last well beyond six weeks; this is known as chronic urticaria. Fifty percent of those affected by chronic urticaria have autoimmune disorder markers like positive ANA, anti-thyroid antibodies, and hypothyroidism.
The hyper-reactive immune response and impaired skin barrier function that characterize atopic dermatitis mean that people with eczema are more prone to allergy-related hives. Other atopic disorders such as asthma and hay fever are also risk factors.
What Causes Hives?
Urticaria is the result of inflammation and has a wide variety of causes. It sometimes occurs with infection, either bacterial (like strep) or viral respiratory viral infections, both subclinical (no symptoms), and weeks following a known infection. Dermatologists often conclude that an episode of urticaria followed a viral infection. The mechanism of viruses triggering urticaria is considered immunologic but is not understood yet.
Food allergies are a common trigger, as are allergies to medication–penicillin and sulfa drugs are common culprits. Urticaria most often occurs after contact with an irritant or allergen in the external environment.
Urticaria arises when the mast cells are activated by any number of triggers. Through a cellular process known as degranulation, the mast cells release histamines in response to triggers. This causes the blood vessels to dilate, which then leads to a leakage of fluid within the skin. This leakage of fluid, or edema, is recognizable in the swelling and redness of hives..
Many acute cases of urticaria are caused by the aforementioned mast cell activation and the resulting burst of histamines. In these cases, the mast cells are activated through receptors associated with our innate immune system.
In other cases, especially where chronic urticaria is concerned, it seems that the adaptive immune system becomes involved. In these cases, T cells or antibodies (such as immunoglobulin G (IgG) or immunoglobulin E (IgE)) trigger the degranulation of the mast cells and the burst of histamine that follows. This is known as immunological urticaria.
Different Triggers: What Brings On Hives
We’ve mentioned that allergies to foods, medicines, or environmental irritants can cause hives. There are a whole host of triggers, though, many of which might surprise you.
Predictably, is caused by exposure to sunlight. The reaction is more severe the more skin is exposed to the sunlight. Hives usually resolve within 24 hours after sun exposure has ended. Solar urticaria might be mild and easily mitigated by wearing protective clothing. It sometimes becomes severe, with sun exposure triggering anaphylaxis.
No one is certain what causes solar urticaria, and it is a chronic, lifelong problem in most cases. Limiting sun exposure and using a quality sunscreen are key in the prevention of hives for people afflicted with this highly inconvenient form of urticaria.
Primary cold urticaria
is a disorder most often seen in children and young adults. Within minutes of exposing the skin to a cold solid or fluid, itching and whealing presents at the site of exposure. The wheal lasts for 30 minutes or less in most cases.
This kind of urticaria can occur in the oropharynx in response to cold drinks. Severe, anaphylaxis-like symptoms sometimes occur if a person with primary acquired cold urticaria is immersed in cold water or otherwise exposed to extremely cold stimuli.
Secondary cold urticaria
Is cold-induced urticaria that occurs with systemic infections, such as hepatitis or HIV, or with autoimmune disorders. It can also occur with some cancer. Treatment of underlying disease is crucial in these cases.
Dermographism (factitious urticaria)
Is common and usually self-limited to a few years. It occurs as welts in streaks associated with scratching and minor trauma. It often begins after a viral infection, and is treated with skin care and the usual antihistamines. Dermatologists often explain to their patient that for a while, they have "too much histamine in their skin." Dermographism is diagnosed by....
Delayed pressure urticaria
Occurs in response to pressure upon the skin. Hives often erupt beneath waistbands, on the palms, and on the soles of the feet. Hives do not erupt immediately; they instead show up two to six hours after exposure, even after the offending pressure is relieved. The hives are distractingly itchy and are frequently painful. Sufferers often experience joint pain as well.
Refers to a mercifully rare reaction to water. Only 50 cases of aquagenic urticaria are documented in the medical literature. Because the trigger is unavoidable, aquagenic urticaria patients must hang their hopes upon oral antihistamines, topical creams, or in some cases, phototherapy.
Is a rare form of hives that are triggered by vibrations. A ride on a bumpy road, running, or clapping the hands can trigger hives in this disorder. The rashes do not last long–a small kindness when the trigger is so ubiquitous.
Refers to hives caused by an increase in the body’s core temperature after exercise, and the sweating response which is cholinergic in nature. These are often small itchy bumps surrounded by mild redness.
Is triggered, obviously enough, by exercise. Patients with this kind of urticaria might experience hives on the skin along with other symptoms such as headaches after vigorous exercise. Treatment with antihistamines and avoidance of other common triggers allows some patients to continue exercising. Exercise triggers life-threatening anaphylaxis in other cases; these people must avoid exercise.
Dermatologists quite often see patients with an urticarial version of rebound weed dermatitis, which is prolonged and worsened by exercise. These patients must treat their poison ivy-like weed exposure rashes completely and thoroughly before they can resume exercising with their usual routines.
How are Hives Treated
Antihistamines are the most frequently prescribed medication for hives. The patient may be treated with non-sedating antihistamines such as loratadine or fexofenadine during the day while taking antihistamines with a sedating side effect, such as hydroxyzine or diphenhydramine, at night. For severe, chronic urticaria, doses might be raised and different antihistamines might be used concurrently.
If antihistamines alone do not help, doctors might prescribe doxepin, a tricyclic antidepressant. Montelukast, a leukotriene receptor antagonist, is not universally effective, but certain kinds of urticaria respond well to it. Short doses of prednisolone, a corticosteroid, might be prescribed when other treatments do not work. Corticosteroids have an anti-inflammatory effect and can inhibit the release of histamine. They are not recommended for long-term use.
Especially stubborn cases of chronic urticaria sometimes respond well to treatment with calcineurin inhibitor cyclosporine. Cyclosporine is contraindicated for people with systemic infections, poor kidney function, and cancer.
Monoclonal antibody treatments such as Omalizumab represent a newer approach. This treatment inhibits the effects of IgE. Omalizumab worked well for at least one patient whose urticaria didn’t respond to cyclosporine; however, these treatments are still new and have not yet been thoroughly researched.
Topical treatments with corticosteroids often relieve the itching and redness of hives. SmartLotionⓇ, an over-the-counter corticosteroid cream developed by Board Certified Dermatologist Dr. Steve Harlan, MD, uses a minimal amount of hydrocortisone and superior skin barrier stabilization to relieve the itching and redness of hives.
For most of his patients with hives, Dr. Harlan recommends applying a thin, disappearing layer of SmartLotionⓇ over the affected skin up to four times a day, for a two-week period while using oral antihistamines every day, for 3 to 6 weeks. The idea is to stabilize the cells releasing histamine. It may require months of oral antihistamines under medical supervision.
The cream can cause stinging initially; this temporary reaction can be minimized by applying cold compresses (ice in a plastic bag and covered with a dish towel or paper towel).
Make sure the skin is well moisturized, as dry skin can make the itching worse.
Of course, SmartLotionⓇ should only be used under the guidance of your doctor. Patients should not use SmartLotionⓇ or substitute it for their prescribed treatments without their doctors’ oversight.
SmartLotionⓇ is particularly helpful for chronic urticaria patients who need off-and-on topical care. It's well tolerated. When used appropriately with medical supervision, patients do not need to worry about thinning skin or topical steroid withdrawal, both of which are common side effects of other corticosteroid creams.
As with any condition, prevention is worth a pound of cure. Triggers should be avoided where possible, and treatment should be managed by a physician. Patients with chronic urticaria should see a qualified, board-certified dermatologist and appropriate specialists for any underlying disorders.
- Zula Elwood