Allergic Reactions and Hives
Allergic Reactions and Hives — immune responses in which the skin reacts to a trigger, sometimes producing hives, which are raised, itchy welts that can appear and fade within hours. Reactions may be caused by foods, medications, insect stings, contact with allergens, or other triggers, and can range from mild to severe. Because some reactions can escalate quickly, recognizing warning signs is important.
Key points
- Hives, or urticaria, appear as itchy raised welts that often shift location and fade within 24 hours.
- Common triggers include certain foods, medications, insect stings, latex, and contact allergens.
- Contact allergic reactions to skincare or cosmetic ingredients typically appear where the product was applied.
- Difficulty breathing, swelling of the face or throat, or dizziness requires emergency medical attention.
Frequently asked
How are hives different from other rashes?
Hives are typically raised, itchy welts that can move around the body and often fade within a day, whereas many other rashes stay in place and evolve more slowly. The shifting, transient nature is a key distinguishing feature.
When is an allergic reaction an emergency?
Signs like swelling of the lips, tongue, or throat, trouble breathing, or feeling faint may indicate anaphylaxis, which is a medical emergency. In these cases, seek emergency care immediately.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
