Hives

Hives are itchy bumps on your skin.

They can be red or skin-colored. They might sting or feel hot.

Hives can happen many ways. Some people get them from food. Others get them from bug bites. Some people get them from medicine.

Sometimes, the weather causes hives. Very cold air can trigger them. Being in the sun can too. Stress can also be a cause.

Hives can show up anywhere. They may stay for a few days. Most of the time, they go away soon. They do not leave marks on your skin.

To help, you can avoid what caused them. Doctors can also give medicine to help the itch. It is good to stay cool.

Hives are a type of skin rash. They look like red or skin-colored bumps. These bumps are raised and very itchy.

They can also sting or burn. Hives can show up anywhere on your body.

Hives happen because of a way the body reacts. Tiny parts in the skin called mast cells let out a substance called histamine. This causes fluid to leak from small blood vessels. This fluid creates the bumps.

Many things can cause hives. Some people get them from food, like nuts or shellfish. Others get them from medicine or bug bites. Even stress or cold weather can be a trigger. Some people have hives from touching their skin. We call this dermatographic urticaria. This happens when scratching or stroking the skin makes welts appear.

Most hives go away in a few days. They do not leave marks on the skin. If hives last more than six weeks, they are called chronic urticaria. Doctors often use antihistamines to help the itch. These are medicines that block histamine. You can also stay cool to help your skin feel better.

Hives are a common type of skin rash. They appear as red or flesh-colored bumps that are raised on the skin.

These bumps can feel very itchy, or they might sting and burn. You can find hives anywhere on the surface of your body.

Most cases of hives are short-lived and last only a few minutes or days. They usually do not leave any lasting marks on the skin once they heal. However, if hives last for more than six weeks, doctors call this chronic urticaria. About 20% of people will deal with hives at some point in their lives.

Hives happen because of a specific way the body reacts. Inside the skin, there are tiny parts called mast cells.

When these cells are triggered, they release a substance called histamine. This histamine causes fluid to leak out of small blood vessels in the skin. This leakage creates the swelling that we see as raised bumps.

Sometimes, this fluid leaks from much deeper vessels. This deeper swelling is a related condition called angioedema. While most hives are harmless, some can be more serious if they leave bruises or last a very long time.

Many different things can trigger these skin reactions. Some people get hives from eating certain foods like nuts, shellfish, eggs, or wheat. Others might react to medicines such as penicillin or aspirin. Even physical things like insect bites, cold temperatures, or stress can cause them. There is even a type called dermatographic urticaria, which is often called "skin writing." In this case, simply stroking or scratching the skin causes raised welts to appear. This happens to about 4% to 5% of people.

People have known about hives for a very long time. They were described as far back as the time of Hippocrates. The scientific name for hives is urticaria. This name comes from the Latin word "urtica," which means nettle. This is a good way to remember them because nettles are plants that sting the skin. Doctors often use patch testing to help figure out exactly what an allergy might be. Knowing the cause helps people avoid the thing that makes them itchy.

There are many ways to help manage the itching and swelling. Most people use antihistamines to treat the reaction. These are medicines that help block the histamine in the body. Some doctors prefer second-generation antihistamines like cetirizine or loratadine because they do not make people as sleepy. For very stubborn cases, doctors might use other medicines called corticosteroids. Staying in a cool environment can also help the skin feel better. If someone has hives from the cold, they must be very careful to protect their body temperature.

Hives, scientifically known as urticaria, are a common skin rash characterized by red or flesh-colored, raised bumps.

These bumps may itch intensely, or they might cause a stinging or burning sensation. Hives can appear anywhere on the skin's surface. They may be as small as a pinpoint or several inches in diameter. They can also appear as individual bumps or merge together into larger patches. Most cases are short-lived and do not leave lasting marks on the skin. However, if hives last for more than six weeks, the condition is called chronic urticaria.

The biological mechanism behind hives involves a complex inflammatory reaction. Inside the skin, there are specialized cells called cutaneous mast cells. When triggered, these cells release inflammatory mediators, including a substance called histamine. This release causes fluid to leak from superficial blood vessels in the dermis. This leakage creates the swelling, or edema, that forms the visible bumps.

A related condition is angioedema. In angioedema, the fluid leakage occurs from much deeper blood vessels in the subcutaneous or submucosal layers. While most hives are benign, urticarial vasculitis is a more serious condition. It is identified by hives that are painful, last over 24 hours, or leave a bruise during healing.

There are many different types of urticaria classified by their triggers. Dermatographic urticaria, or "skin writing," occurs when stroking or scratching the skin creates raised welts. This affects about 4% to 5% of the population. Another type is cholinergic urticaria (CU), which is provoked by sweating from exercise, bathing, or emotional stress. Cold urticaria is caused by exposure to extreme cold or damp conditions. This can manifest as a rare hereditary form or a common form on the face and hands. Solar urticaria appears on skin exposed to the sun, while aquagenic urticaria is triggered by contact with water.

Physical triggers can also include pressure and exercise. Pressure urticaria can occur immediately or as a deferred response about six hours after pressure is applied. This can be caused by tight clothing, belts, or sitting on hard surfaces. Exercise urticaria (EU) is a distinct condition first identified in 1980. People with EU experience hives, shortness of breath, and low blood pressure within five to 30 minutes of starting exercise. Jogging is a common trigger for this condition. In some cases, EU only occurs if a person exercises within 30 minutes of eating specific foods like wheat or shellfish.

Understanding the causes of hives involves looking at various environmental and biological agents. Many people experience hives due to allergic reactions to medications, such as penicillin, aspirin, or ibuprofen. Food allergies are also common; shellfish and nuts are frequent triggers for adults, while eggs, wheat, and soy are common in children. Some people may even have an alpha-gal allergy, causing sensitivity to red meat and milk. Infections, such as those caused by Streptococcus or certain parasites, can also trigger hives. In over 50% of chronic cases where the cause is unknown, an autoimmune reaction is likely responsible.

History shows that humans have recognized hives for millennia. The condition has been described since at least the time of Hippocrates. The medical term urticaria is derived from the Latin word "urtica," which means nettle. This name reflects the stinging sensation similar to touching a nettle plant. Approximately 20% of the population will experience hives at some point in their lives. While short-duration cases affect males and females equally, long-duration cases are more common in females. Short-duration cases are more common in children, whereas long-duration cases are more frequent in middle-aged individuals.

Treatment and prevention depend heavily on identifying the specific trigger. The primary method of prevention is avoiding the substance or agent that causes the reaction. Doctors often use patch testing to help identify specific allergies. For most people, antihistamines are the preferred treatment. Second-generation antihistamines, such as fexofenadine, loratadine, and cetirizine, are often chosen because they carry a lower risk of sedation. In stubborn or refractory cases, doctors may prescribe corticosteroids or leukotriene inhibitors. For chronic cases lasting over six weeks, long-term antihistamine therapy or immunosuppressants like omalizumab may be required.