The effects of hives (hives) can be very noticeable, but the symptoms can be similar to those of other skin conditions such as eczema , rosacea , and pityriasis . Although areas of hives on the skin (also called blisters or blisters) can vary in their location and appearance, they are characterized by raised, itchy scars on the surface of the skin that may be red or flesh-colored.
Hives are caused by an inflammatory reaction that causes capillaries in the dermis (the layer of tissue just below the outer skin) to allow fluid to pass through. When this happens, the accumulation of fluid results in a specific raised area of skin that persists until the fluid is finally reabsorbed into the surrounding cells .
Hives have certain characteristics that differentiate them from other skin conditions:
- The raised area of the skin has a well-defined border.
- When you press on the rash, it "turns white" (turns white).
- They will sting, sometimes a lot. They can also be associated with pain or burning sensation.
- They can appear anywhere on the body and change shape, move, disappear, and reappear for short periods of time.
- When they resolve, the skin will return to its normal state without scarring.
- Most of these will not be accompanied by systemic reactions such as fever, nausea, muscle pain, joint pain, or headaches.
Hives are classified as acute or chronic depending on the duration of the rash. Acute hives last less than six weeks and chronic hives last much longer than six weeks .
Acute hives are more common in children and young adults. Most of them are classified as idiopathic, which means that we do not know the cause. Most cases are self-limited; individual injuries usually resolve on their own within a few hours. The rash rarely lasts more than a few days, although it may reappear after a few weeks. If a cause is found, it is usually associated with an infection, insect bite, food or drug allergy.
In contrast, chronic hives often require treatment. In a 2013 study, 70% of people with chronic hives had symptoms that lasted more than a year, and 14% had them for five or more years. In half of the cases, no underlying disease was found.
Hives are known to affect up to 20% of the population and affect people regardless of age, race or gender. Hives most often appear at night or early in the morning immediately after waking up. The itching is usually worse at night and often disrupts sleep.
The distribution and appearance of hives can vary significantly. Some may be generalized or diffuse, while others may be limited to a small blister. The appearance of a hive can sometimes indicate an underlying cause.
- Cold Urticaria : This type is caused by exposure to low temperatures and usually presents with scars that range from a quarter of an inch to an inch, slightly reddish or flesh-colored. Fainting can occur when large areas of the skin are affected.
- Cholinergic urticaria – Also known as heat rash, this type is caused by excessive sweating and appears as very small blisters surrounded by bright red flashes. Exercise is a common cause.
- Dermographic urticaria : This type is caused by heavy contact with the skin and manifests as hives along the line of contact. The waves appear between 5 and 10 minutes after contact and usually disappear between 10 and 15 minutes after their appearance.
- Compressive urticaria – is caused by any pressure on the skin, including tight clothing or standing for too long. This results in a thick, localized rash that is red, itchy, and possibly even slightly painful.
- Solar hives: Exposure to ultraviolet (UV) light can cause hives on exposed skin, often within minutes of exposure. The rash is very itchy and appears "angry", often with severe redness and warmth. As with cold urticaria, fainting with extensive hives can occur.
- Vibrant hives . Vibration, even clapping your hands or driving your car over bumps, can cause hives. As a general rule, they are short-lived, appear and disappear within an hour. Although vibratory urticaria is difficult to distinguish in appearance alone, it sometimes presents with unusual symptoms such as red skin, headaches, blurred vision, or a metallic taste in the mouth.
- Aquatic urticaria (aquatic urticaria) – This is a rare form of hives caused by contact with water. Hives are usually small and most often develop on the neck, upper body, and arms. Like vibratory urticaria, it can come and go within an hour.
Less commonly, hives can progress to a severe general allergic reaction known as anaphylaxis . Anaphylaxis is often caused by a hyperallergic reaction that causes hives, angioedema (a related skin condition that affects the deeper layers of tissue), and severe respiratory symptoms.
Common allergy triggers include food, medications, vaccinations, and insect bites, although in some cases the cause is unknown.
Symptoms of anaphylaxis include:
- Frequent urticaria and angioedema
- Coughing, sneezing, and wheezing.
- Sore throat and shortness of breath.
- Swelling of the lips and / or tongue.
- Fast or irregular heartbeat
- Dizziness or lightheadedness
- Stomach cramps
- Nausea, vomiting, and diarrhea.
- Chest pain
- Restriction of breathing leading to airway obstruction.
- Feeling of impending doom
- Fainting and collapse
If left untreated, anaphylaxis can lead to shock , suffocation, coma, heart or respiratory failure, and death.
When to contact a healthcare provider
If your hives are uncomplicated and you have no symptoms other than itching, you can usually treat it at home . Most of them dissolve within a few hours or a few days. If it persists for more than a week or starts to get worse, see your doctor as soon as possible.
Hives Discussion Guide for Healthcare Providers
Get our printed guide to your next doctor's appointment to help you ask the right questions.
If your symptoms return and are unexplained, ask your healthcare provider for a referral to a dermatologist who will perform tests to identify potential triggers or an allergist who can check to see if the allergen (allergic trigger) is the culprit. Your healthcare provider may also want to check for undiagnosed infections (such as hepatitis B ) or autoimmune diseases (such as Hashimoto's thyroiditis), for which recurrent hives are common.
If your hives are accompanied by symptoms such as shortness of breath, generalized edema, irregular heartbeat, and / or vomiting, call 911 or have someone drive you to the nearest emergency room.
Frequently asked questions
Hives are a common skin reaction that causes itchy scars that range in size from tiny patches to patches the size of plaque. They are often accompanied by angioedema, a condition characterized by swelling of the deeper tissues.
Hives can occur when the body's immune system responds abnormally to environmental or medical conditions and triggers the release of histamine into the bloodstream. This causes the blood vessels to dilate rapidly and the fluid to leak into the upper layers of the skin. Sometimes there is no reason.
The duration of hives depends on the underlying cause. Hives often go away spontaneously and quickly on their own; other cases may be permanent or repetitive. Chronic hives are daily hives that last more than six weeks.
Common triggers for hives include:
- Food allergies
- Hypersensitivity to drugs.
- Allergens in the air
- Contact allergens
- Insect bites
- The exercise
- Changes in the environment (such as temperature fluctuations, excessive sun exposure, or strong vibrations)
- Applying direct pressure to the skin (for example, wearing tight clothing)
- Certain medical conditions (such as HIV or hepatitis)
- Blood transfusion
Depending on the severity of your hives, your healthcare provider may recommend over-the-counter or prescription antihistamines to help relieve itching and swelling. Severe cases may require the use of a biological drug called Xolair (omalizumab) , which is approved by the FDA to treat chronic hives, or an unauthorized immunosuppressant such as cyclosporine .