It's often impossible to find out exactly why hives have formed. Hives cause reddish welts on your skin, which may be harder to see on darker skin tones. (Photo credit: iStock/Getty Images ...

In most situations, histamine causes your blood vessels to dilate and leak fluid, creating the raised areas on your skin (hives). Histamine also affects your nerve cells, signaling your skin to ...

You may also have other forms of hives. Hereditary angioedema: Painful swelling under the skin. It runs in families. Your doctor will ask you many questions to try to find the cause of hives or ...

If sweat cannot escape to the skin's surface, the blockage causes what's known as a prickly heat rash marked by vesicles ...

They’re caused by allergies or allergy-like skin reactions to irritants. Hives are a type of rash. There are many other types of rashes. A rash causes patches of redness, swelling, itching ...

Understanding the causes, symptoms, treatment options, and why urticaria may worsen at night is essential for effective management. Urticaria is an inflammatory skin disorder. According to the ...

A rash is defined as a widespread eruption of skin lesions. It is a very broad medical term. Rashes can vary widely in appearance. Their causes range from insect bites to HIV and reactions to ...

a rare but potentially severe condition that can cause developmental issues. Roseola is a common viral skin rash in babies. It’s contagious and caused by human herpesvirus 6, which affects ...

Both are itchy skin conditions that stem from an immune system response. And they can look similar, too. “Hives and eczema can both cause skin to appear red and swollen. As a result, people may ...