Hives are a common skin reaction appearing as itchy, raised welts on the skin. These welts, often red or skin-colored, can vary greatly in size, from as small as a fingertip to as large as a dinner plate. They tend to appear suddenly, change shape, and usually fade within a few hours, though new ones may continue to emerge. Some people may also experience a burning or stinging sensation alongside the itchiness.
Are Hives Contagious?
Hives are not contagious; they cannot spread from person to person. This is because hives are a skin reaction, specifically an immune response, rather than an infection caused by transmissible bacteria, viruses, or fungi. Your body releases a chemical called histamine, which causes fluid to leak from small blood vessels under the skin, leading to the characteristic swelling and itchiness of hives.
While hives can spread across an individual’s body, getting larger or joining together, this is a localized response within the affected person. Sometimes, hives may appear when someone has a contagious illness, like strep throat or a common cold, but it is the underlying infection that is contagious, not the hives themselves. The body’s immune response to the infection releases histamine, which then causes the hives.
Common Causes of Hives
Hives often arise when the body reacts to certain triggers. Many cases are linked to allergic reactions. Common allergic triggers include foods like nuts, shellfish, eggs, and milk. Medications, particularly antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, can also induce hives. Other allergens like insect stings or bites, pet dander, pollen, and latex can also cause hives.
Hives can also result from non-allergic factors. Stress is a known trigger, as it can lead to the release of chemicals that promote histamine production. Infections, both viral and bacterial, are a common cause, especially in children. Physical stimuli can also trigger hives, a condition known as physical urticaria. These can include pressure on the skin, exposure to cold or heat, sunlight, exercise, or excessive sweating. Certain chemicals and underlying medical conditions like lupus can also cause hives.
When to Seek Medical Attention
While many cases of hives are temporary and resolve on their own, medical attention is advisable in some situations. You should contact a healthcare provider if your hives are widespread, severe, or persistent, lasting more than a few days without improvement. Hives that recur frequently, appearing almost daily for six weeks or longer, indicate chronic urticaria, which often requires professional diagnosis and management.
Immediate medical attention is necessary if hives are accompanied by signs of a severe allergic reaction, known as anaphylaxis. These symptoms include difficulty breathing, wheezing, swelling of the face, lips, tongue, or throat (angioedema), dizziness, or a sudden drop in blood pressure. Such symptoms signal a medical emergency. If hives significantly disrupt sleep or daily activities due to intense itching or discomfort, seeking medical advice can help improve quality of life and explore treatment options.