Urticaria, more widely known as hives, is a skin reaction that causes patches of itchy welts. The patches can develop anywhere on the body, including the mucous membranes that line the mouth, eyelids, and similar areas.
If you or someone you know is prone to skin reactions, it helps to understand the signs and symptoms of hives so you can determine which are mild breakouts and which might require medical treatment.
The clearest symptoms of hives are raised patches of skin. While the shape and size of the welts can vary dramatically from person to person, most cases appear in batches.
People with light or medium skin tones can press on a welt, and the red color will disappear. This is called blanching and is a telltale sign of hives.
Though hives can have mild itchiness—or no itching sensation at all—it is far more common to feel an extreme itch. Additionally, some people say that hives sting or burn rather than itch, though this could indicate an underlying systemic illness.
The itching sensation usually appears shortly after the rash first develops, due to the release of hormones like histamine.
Depending on a person’s skin tone, hives will have very different colors. Lighter or medium complexions typically see pink or red hives, though some may have a more tan appearance.
People with darker skin tones will notice that hives are either the same color as their skin or slightly darker or lighter than their natural tone.
Except for a form of hives called delayed pressure urticaria, the rashes show up quickly—often developing completely before the person notices. In some cases, it may take as little as a few minutes for a rash to form following a trigger.
Depending on the cause, the welts may heal as quickly as they formed or persist for a notable amount of time.
In cases of acute urticaria, the individual rashes will appear and disappear over the course of about 24 to 48 hours. As some hives quickly heal, others form elsewhere on the body.
This process typically occurs for a few days, lasting up to a few weeks. If the condition persists, it indicates a case of chronic urticaria and underlying issues.
Hives cause inflammation in the skin, making it swollen and hot to the touch. Around 40% of people with hives also experience another type of inflammation that affects the mucous membranes of their lips, mouths, eyelids, and other regions of their bodies.
This swelling is called angioedema and is typically painful rather than just itchy. Most cases of angioedema last for two to three days.
At the start, hives tend to form as singular, defined rashes or welts. Over time, they may begin to migrate and merge together, forming large patches of inflamed, itchy skin. These combined patches are called plaques.
Because the itching or burning sensation affects such a large portion of the body, plaques are extremely uncomfortable.
Though it does not technically occur due to the hives, fever is an important diagnostic symptom for certain types of urticaria.
When a fever occurs alongside the other signature signs of hives, this points to some specific underlying conditions as the cause. Autoimmune disease, lymphoma, and urticarial vasculitis can all cause hives with fever and require much more serious care and attention.
Hives sometimes develop in response to a physical trigger, such as a temperature change, pressure, water, exercise, sunlight, or vibration.
Rashes from physical urticaria tend to vanish more quickly. People with cold urticaria may have a rare underlying condition that can also trigger symptoms like hypotension in response to cold water.
Though rare, some people develop hives as part of the hormonal changes in their menstrual cycle. Known as autoimmune progesterone urticaria, the rashes usually appear about seven to 10 days before the period begins.
Hives often improve during pregnancy, though there are uncommon cases of rashes appearing and worsening in the third trimester. This is most common in first pregnancies.
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.