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What Are Hives?  

Allergic reactions on the skin can manifest themselves in different forms and one of the most common conditions that may appear suddenly is hives. Hives are also known as urticaria and they can develop anywhere on the body as red, swollen, and bumpy rashes. These patches are also commonly referred to as welts or wheals. 

Aside from its unsightly appearance, a hive rash can also feel itchy and have a slight burning or stinging sensation. They’re not contagious, but you can develop them suddenly if you catch an infectious disease such as a cold, strep throat, or urinary tract infection. 

Once you have hives, there’s a possibility that they will migrate around the body. One area of your skin may have redness and itching for a few hours before disappearing and reappearing somewhere else.

What Causes Hives to Appear on the Skin?  

Hives are a normal skin reaction that occurs when your immune system recognizes an unknown substance. To defend your body against potential threats, the immune system will send histamine and other chemicals into your bloodstream. Sometimes, histamines can get released unexpectedly even when there is no threat and this can happen in cases of: 

  • Too much stress
  • A skin reaction to extreme cold or hot temperatures  
  • Exposure to UV light and sunlight 
  • Pressure on the skin from wearing tight clothing or scratching 

In some people, hives can occur as a result of an allergic reaction when they come into contact with a specific allergen or touch certain materials that they are sensitive to. Some of the most common triggers for urticaria are:

  • Insect bite
  • Latex 
  • Parasites sting 
  • Food allergy from shellfish, peanuts, tree nuts, milk, and eggs
  • Viral and bacterial infections 
  • Autoimmune diseases
  • Thyroid disease
  • Pollen 
  • Hay fever
  • Animal dander or pet allergy  
  • Certain oral medications and antibiotics

The Difference Between Acute and Chronic Hives 

Hives can be categorized into 2 main types: acute urticaria and chronic urticaria. As with any medical condition, acute hives are short-term skin reactions that can appear suddenly and last no more than 6 weeks. They’re usually caused by an allergic reaction or a viral infection. 

Most acute hives can clear away after a few days or weeks, but they may recur when you are exposed again to a particular allergen. Some of the most common triggers of acute urticaria are an insect sting, medications, and certain foods. 

On the other hand, chronic hives are itchy welts that can last for more than 6 weeks. This type of urticaria can come and go suddenly, and they are less likely to be caused by an allergy. Chronic urticaria may develop due to stress, autoimmune disorders, hormonal changes, or other systemic problems. 

Some people can never identify the cause of their skin hives. In these cases, their condition is known as chronic idiopathic urticaria.  

Physical Urticaria: Another Form of Skin Hives 

There are also other sub-forms of hives depending on the cause and trigger of the skin reaction. The most common subtype is physical urticaria which are hives caused by direct stimulation of the skin. Any excessive rubbing or scratching can cause irritation and lead to a skin reaction. 

Physical urticaria can have other forms such as: 

  • Cholinergic urticaria - a type of hives that develops from an increase in body temperature and sweat. They can break out after a particularly intense workout when you’re feeling hot and sweaty.
  • Pressure urticaria - this type of urticaria happens as a response to constant pressure on the skin. This usually occurs along with fatigue, body aches, and body temperature increase. It can also be a result of an autoimmune disease.
  • Solar urticaria - this skin reaction happens when you have sensitivity to sunlight exposure and UV light.
  • Dermatographism - this is a form of localized hives that appears where the skin is scratched. This is one of the common urticarias that can affect nearly 5% of individuals.

Dr. Greenberg at Sunshine State Dermatology and Skin Cancer Center specializes in treating hives and takes a personalized approach to develop the best treatment plan for each patient.