Urticaria, commonly known as hives, is a skin condition characterized by the sudden appearance of raised, red, and intensely itchy welts. These welts can vary in size from small spots to large plaques and often form in clusters on various parts of the body, including the face, arms, legs, and trunk. A defining feature of urticaria is its evanescent nature; individual welts typically fade within 24 hours without leaving a mark, though new ones may appear elsewhere.
This reaction occurs when the body's mast cells release histamine and other chemicals into the bloodstream, causing small blood vessels to leak fluid and leading to the formation of swollen welts. In some cases, urticaria can be accompanied by angioedema—a deeper swelling of the skin, often around the eyes, lips, hands, or feet. Angioedema can cause a sensation of tightness or pain and requires immediate medical attention if it affects the throat or tongue and impedes breathing.
**Types of Urticaria**
Urticaria is primarily classified by its duration:
* **Acute Urticaria:** The most common form, lasting less than six weeks. A specific trigger, such as an allergy or infection, is often identifiable.
* **Chronic Urticaria:** Diagnosed when outbreaks recur for more than six weeks. In many cases, the cause is difficult to determine, a condition known as chronic spontaneous (or idiopathic) urticaria, which may be autoimmune in nature.
There is also **Inducible or Physical Urticaria**, triggered by specific external stimuli like:
* **Dermographism:** Welts caused by scratching or rubbing the skin.
* **Cold Urticaria:** Triggered by exposure to cold.
* **Cholinergic Urticaria:** Caused by an increase in body temperature from exercise or heat.
* **Pressure Urticaria:** Results from sustained pressure on the skin.
* **Solar Urticaria:** Induced by sunlight.
**Common Causes and Triggers**
The triggers for acute urticaria are wide-ranging and include:
* Allergic reactions to foods (e.g., nuts, shellfish, eggs), medications (e.g., antibiotics, aspirin), insect stings, or latex.
* Viral or bacterial infections, such as the common cold or strep throat.
* The physical factors listed above.
* Emotional stress, which can exacerbate outbreaks in susceptible individuals.
**Diagnosis and Treatment**
Diagnosis is primarily based on a physical examination and a detailed review of the patient's medical history to identify the outbreak pattern and potential triggers.
Treatment focuses on symptom relief and avoiding known triggers:
* **Antihistamines:** These are the first-line treatment. They work by blocking the effects of histamine, effectively reducing itching and the formation of new welts.
* **Corticosteroids:** For severe or persistent outbreaks, a short course of oral corticosteroids may be prescribed to reduce inflammation.
* **Trigger Avoidance:** The most effective strategy is to identify and avoid specific triggers, such as a particular food or medication.
While often transient and benign, urticaria can significantly impact a person's quality of life. Understanding its causes and working with a healthcare provider on an effective management plan is key to controlling this disconcerting skin condition.
