The rash often comes and goes, with individual welts sometimes disappearing within hours and new ones appearing elsewhere on the skin. The condition occurs when substances such as histamine are released in the skin, leading to swelling and irritation of the surface of the skin.

Common Symptoms

Symptoms of hives may include:

• raised red or skin-coloured welts on the skin
• itching that may be mild or severe
• swelling of the affected skin
• patches that change size or shape
• welts that disappear and reappear in different areas

In some cases, deeper swelling of the skin may occur, particularly around the lips, eyelids, hands or feet.

Possible Causes

Hives can be triggered by many different factors. These may include allergic reactions to foods or medications, infections, insect bites or stings, exposure to cold or heat, physical pressure on the skin, or emotional stress. In some cases, the exact cause may not be identified.

Reference

Content adapted from information provided by Ontario Health – Health811:https://health811.ontario.ca/static/guest/medical-library/condition?name=hives