Urticaria, commonly known as hives, is a skin condition characterized by itchy, raised welts or bumps. These welts vary in size, often appearing red on lighter skin tones and sometimes blending into the surrounding skin on darker skin. Intense itching is a hallmark symptom, and welts typically blanch when pressed. Hives are common.
Acute Versus Chronic Urticaria
Urticaria is categorized by symptom duration. Acute urticaria resolves within six weeks. It is often triggered by identifiable external factors. Common triggers include infections, such as viral or bacterial illnesses, which provoke an immune response.
Medications like antibiotics, NSAIDs, and opioids are common causes. Food allergies, such as to peanuts, shellfish, milk, or eggs, can also cause hives. Additionally, insect bites or stings can induce acute urticaria.
In contrast, chronic urticaria is diagnosed when hives persist for six weeks or longer, with new welts appearing almost daily. Its cause is often idiopathic, meaning no specific external trigger is identified. While acute urticaria typically resolves once the trigger is removed or infection clears, chronic urticaria can be a long-term condition.
Understanding Chronic Inducible Urticaria
Chronic inducible urticarias are specific types of chronic urticaria where hives appear predictably upon exposure to distinct physical stimuli. One type is dermatographism, or “skin writing,” where raised red lines or welts appear after firm scratching or rubbing. This occurs because physical pressure stimulates mast cells to release histamine.
Cold urticaria manifests as hives, swelling, and itching when skin is exposed to cold temperatures, such as cold air, water, or cold food. Pressure urticaria involves deep, painful swelling and hives at sites of sustained pressure, like from tight clothing or sitting on a hard surface. These reactions often appear several hours after pressure, distinguishing them from immediate reactions.
Cholinergic urticaria is characterized by small, intensely itchy hives that emerge in response to an increase in body temperature. Activities such as exercise, hot baths or showers, emotional stress, or eating spicy food can trigger these tiny welts. These hives are typically surrounded by a red flare. Solar urticaria is a rare condition where hives appear rapidly on skin exposed to sunlight, typically within minutes.
Aquagenic urticaria is an extremely rare type where hives develop after contact with water, regardless of its temperature. Individuals experience itching, redness, and small welts within minutes of water exposure. These inducible forms involve specific sensitivities within the skin’s immune cells to their respective triggers.
Identifying Urticaria and Seeking Professional Guidance
Recognizing urticaria’s distinct patterns, including triggers, duration, and appearance, can provide clues about its type. For instance, hives after scratching suggest dermatographism, while temperature links point to cold or cholinergic urticaria. However, self-diagnosis is insufficient for proper management.
Consulting a healthcare professional is essential for an accurate diagnosis due to urticaria’s varied causes and types. Dermatologists, specializing in skin conditions, and allergists, focusing on allergic and immunological disorders, are best equipped to evaluate hives. They can differentiate between forms of urticaria and rule out similar skin conditions.
The diagnostic process begins with a thorough medical history, asking about onset, duration, and potential triggers. A physical examination assesses welt appearance and distribution. For inducible forms, trigger tests, such as applying ice for cold urticaria or stroking the skin for dermatographism, confirm diagnosis. Blood tests may also be ordered to check for underlying conditions or autoimmune markers, especially when the cause is not readily apparent.