Pictures of Hives to Help Identify a Rash

Hives, also known as urticaria, are a type of skin rash with raised, red, itchy bumps or welts. They can affect people of any age on any part of the body. Causes include stress, viral or bacterial infections, food or latex allergies, medications, and physical stimuli such as heat, cold, or exercise. Hives may also be idiopathic (meaning of no known cause).

Hives may be acute (sudden and severe) or chronic (persistent or recurrent). They can also be generalized (widespread) or localized (limited to a certain area). These characteristics can help a healthcare provider narrow the possible causes.

This article offers a gallery of pictures of hives, describing their unique characteristics and the possible causes and treatments.

Acute Hives

Acute hives are common and tend to be harmless, Technically, acute hives can last up to six weeks, though they typically resolve within a few days and may be "once-off" events.

Acute hives are often the result of exposure to an allergy-causing substance (known as an allergen) that you either touch, breathe in, or put into your body. This triggers an immune response in which an antibody called immunoglobulin E (IgE) is released into the bloodstream, instigating allergy symptoms affecting the skin and other parts of the body.

But there are also immune reactions that don't involve IgE that can also cause acute urticaria. These include certain infections and diseases.

Acute urticaria can often be diagnosed by reviewing a person's medical history, current medication use, recent infections, changes in lifestyle or environment, or a family history of hives. The timing, location, and severity of symptoms are also factored in. Allergy tests may be ordered to help identify allergens you may be sensitive to.

But, even with these evaluations, the cause may still be unknown.

Acute hives can be generalized and localized. Generalized hives are more often seen with allergens that are ingested, like food or medications. Localized hives are more commonly seen with contact allergens.

The hives may also look spongy due to the rapid build-up of fluid the beneath the surface of the skin. This is because IgE-mediated allergic reactions involve a chemical called histamine that causes blood vessels under the skin to dilate (widen) and release fluid into surrounding tissues.

Acute hives are commonly treated with second-generation H1 antihistamines that help relieve swelling and itching. Over-the-counter (OTC) options include:

• Allegra (fexofenadine)
  
• Claritin (loratadine)
  
• Xyzal (levocetirizine)
  
• Zyrtec (cetirizine)

First-generation H1 antihistamines, which tend to cause drowsiness, may be prescribed if symptoms are severe and interfering with your sleep. This includes Benadryl (diphenhydramine).

Not all cases of acute hives are harmless. Those that are sudden and severe may be associated with anaphylaxis, a potentially life-threatening, whole-body allergy. If not treated as a medical emergency, anaphylaxis can lead to shock, coma, heart or respiratory failure, and even death.

Chronic Hives

Where acute hives last for less than six weeks, chronic hives are those that persist for more than six weeks and/or recur frequently over months or years. By definition, chronic hives are visible at least twice per week for more than six weeks.

Chronic hives tend to be localized, although some cases may be generalized (particularly with cholinergic urticaria). The hives commonly appear as splotchy welts with raised edges and well-defined borders. They tend to be less spongy than acute hives.

Chronic urticaria is poorly understood and is thought by many to involve an autoimmune response. This is when the immune system reacts to otherwise harmless stimuli and launches an attack against its own cells and tissues. With chronic urticaria, the target of the assault is the middle layer of the skin, called the dermis.

Females are affected by chronic urticaria more than males. People also tend to have co-occurring atopic (allergy-related) conditions like asthma, eczema, and allergic rhinitis (hay fever).

There are various types of chronic urticaria characterized by their underlying trigger:

• Cholinergic urticaria (induced by heat, stress, or exercise)
• Cold urticaria (induced by sudden exposure to extreme cold)
• Pressure urticaria (caused by things like tight belts or standing too long)
• Aquagenic urticaria (caused by exposure to water)
• Solar urticaria (caused by exposure to UV radiation from the sun)
• Vibratory urticaria (caused by exposure to vibrations)

Females tend to be affected more than males. People with chronic hives also tend to have other atopic (allergy-causing) conditions like asthma, eczema, and allergic rhinitis (hay fever).

Chronic hives can be treated with H1 antihistamines. In some cases, additional drugs may be added to the treatment plan, including H2 antihistamines like Pepcid AC (famotidine) which are normally used for heartburn. Severe cases may require oral steroids like prednisone or injectable anti-inflammatory drugs like Xolair (omalizumab).

Dermatographism

Dermatographism is a form of pressure urticaria in which hives will form along the lines of trauma wherever the skin is scratched, rubbed, or roughly stroked. The term "dermatographism" literally means the ability to write on the skin.

The cause of dermatographism is unknown, but it is thought to be directly induced by mast cells that are situated just under the surface of the skin. These immune cells will degranulate (break open) whenever there is a perceived threat, releasing histamine into the skin.

Dermatographic hives—like many chronic hives—tend to be less spongy and more well-defined because the release of histamine is limited to the skin (unlike many allergies in which histamine is released throughout the body).

In most cases, dermatographic hives will clear on their own within 15 to 30 minutes. In extreme cases, the itchy, red welts may persist anywhere from a few hours to a few days.

Under normal circumstances, treatment is not needed because symptoms are typically short-lasting. Instead, efforts may be focused on preventing scratching or abrasion.

Moisturizers may reduce the body's overreaction to pressure stimuli. In extreme cases, the same treatments used for other forms of chronic hives may be prescribed.

Summary

Hives (urticaria) are a type of rash that causes raised, red, itchy bumps or welts. Hives may be acute, appearing quickly and usually resolving quickly on their own. Or, they may be chronic, lasting for more than six months and/or recurring frequently over months or years.

There are many possible causes of hives, including allergies, infections, stress, cold, vibration, exercise, and even scratching. Chronic hives are often idiopathic, meaning of unknown origin, and may develop spontaneously for no apparent reason.

Hives are ultimately caused by an abnormal immune response in which inflammatory chemicals, including histamine, are released into the bloodstream and tissues. Antihistamines may be used to relieve the swelling, redness, or itchiness of hives. Many cases clear on their own without treatment.