- Hives
There are several types of hives, including:
Acute urticaria.
These are hives that last less than 6 weeks. The most common causes are foods, medications, and infections. Insect bites and diseases may also be responsible.
The most common foods that cause hives are nuts, chocolate, fish, tomatoes, eggs, fresh berries, and milk. Fresh foods cause hives more often than cooked foods. Certain food additives and preservatives may also be to blame.
Chronic urticaria.
These are hives that last more than 6 weeks. The cause is usually harder to identify than those causing acute urticaria. For most people with chronic urticaria, the cause is impossible to find. In some cases, though, the cause may be thyroid disease, hepatitis, infection, or cancer.
Chronic urticaria can also affect organs such as the lungs, muscles, and gastrointestinal tract. Symptoms include shortness of breath, muscle soreness, vomiting, and diarrhea.
Physical urticaria.
These hives are caused by something that stimulates the skin -- for example, cold, heat, sun exposure, vibration, pressure, sweating, or exercise. The hives usually occur right where the skin was stimulated and rarely appear elsewhere. Most of the hives appear within 1 hour.
Dermatographism.
This is a common form of physical urticaria where hives form after firmly stroking or scratching the skin. These hives can also occur along with other forms of urticaria.
The Link to Contact Dermatitis
Contact dermatitis is a painful or itchy rash you get after your skin touches something you're allergic to (allergic contact dermatitis) or that's otherwise irritating to your skin (irritant contact dermatitis). It's not the same as hives. But sometimes people with contact dermatitis also get hives after they come into contact with an allergen.
- Anaphylaxis
Anaphylaxis causes the immune system to release a flood of chemicals that can cause you to go into shock — blood pressure drops suddenly and the airways narrow, blocking breathing. Signs and symptoms include a rapid, weak pulse; a skin rash; and nausea and vomiting. Common triggers include certain foods, some medications, insect venom and latex.
Anaphylaxis requires an injection of epinephrine and a follow-up trip to an emergency room. If you don't have epinephrine, you need to go to an emergency room immediately. If anaphylaxis isn't treated right away, it can be fatal.
- Food allergy
Food allergy is an immune system reaction that occurs soon after eating a certain food. Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives or swollen airways. In some people, a food allergy can cause severe symptoms or even a life-threatening reaction known as anaphylaxis..
- Allergic rhinitis
An allergen is an otherwise harmless substance that causes an allergic reaction. Allergic rhinitis, or hay fever, is an allergic response to specific allergens. Pollen is the most common allergen in seasonal allergic rhinitis. These are allergy symptoms that occur with the change of seasons.
- Contact dermatitis
Contact dermatitis is a rash that crops up on your skin when you touch or have a reaction to a certain substance. It’s red, itchy, and uncomfortable, but it’s not life-threatening.
The rash could be caused by an allergy or because the protective layer of your skin got damaged. Other names for it include allergic contact dermatitis and irritant contact dermatitis.
- Latex allergy
Latex allergy is a reaction to certain proteins found in natural rubber latex, a product made from the rubber tree. If you have a latex allergy, your body mistakes latex for a harmful substance.
- Dust mites allergy
Dust mite allergy is an allergic reaction to tiny bugs that commonly live in house dust. Signs of dust mite allergy include those common to hay fever, such as sneezing and runny nose. Many people with dust mite allergy also experience signs of asthma, such as wheezing and difficulty breathing.
- Drug allergy
Many adverse drug reactions are mediated by the immune system. This can be because the therapeutic effect of the drug targets the immune system. For example, immunosuppressive drugs increase the risk of infections. It is paradoxical that some immunosuppressive drugs can lead to autoimmune reactions.
- Shellfish allergy
Shellfish allergy is an abnormal response by the body's immune system to proteins in certain marine animals. Marine animals in the shellfish category include crustaceans and mollusks, such as shrimp, crab, lobster, squid, oysters, scallops and others.
Some people with shellfish allergy react to all shellfish; others react to only certain kinds. Reactions range from mild symptoms — such as hives or a stuffy nose — to severe and even life-threatening.
- Animal allergy
Allergic reaction to the proteins in animal skin cells usually termed as dander, saliva, or urine which results in runny nose, sneezing, watery eyes, and itching. Causes: Occurs when a person inhales or comes in direct contact with a pet’s fur, dander, or saliva.