Waking up to find your skin covered in itchy, raised red welts can be deeply unsettling. At 73, I pay close attention to my health and any sudden changes in my body, so the unexpected appearance of hives naturally made me anxious. I decided to make a calming cup of chamomile and ginger tea and learn more about the medical science behind hives, also known as urticaria.

Hives develop when immune cells in the skin, called mast cells, release a chemical called histamine. Histamine causes tiny blood vessels beneath the skin to leak fluid into surrounding tissues, creating the raised, itchy welts we recognize as hives. The frustrating part is that the trigger is not always obvious, and it may be caused by more than a traditional allergy.

Stress and emotional exhaustion are possible triggers that many people overlook. When the body is under stress, certain hormones and chemical changes may influence mast-cell activity and contribute to a flare-up. Temperature changes can also cause a form of physical urticaria. Cold wind, cold water, or even holding a cold drink may trigger cold urticaria, while heat from exercise, a hot bath, embarrassment, or sudden stress can cause cholinergic urticaria.

Although hives can be alarming, identifying possible triggers can help you understand your symptoms and avoid future flare-ups. If hives are severe, keep returning, or occur alongside swelling of the lips, tongue, or throat or difficulty breathing, seek urgent medical attention. For persistent or unexplained hives, a healthcare professional can help determine the underlying cause and recommend appropriate treatment.