Hives – What am I allergic to?

shutterstock_46021174The medical term for hives is urticaria and they are described as raised areas of skin that itch intensely and they are red and often have a pale color to the center.  They are common and occur in at least 20% of people at some point in their lives.

Why hives develop:  This skin rash occurs as the body’s immune system is exposed to an allergen (such as a food or chemical) that it inappropriately believes could be harmful.    The body then responds by activating it’s army of immune cells in the skin to fight off the allergen.  When these immune cells (called mast cells) are activated, they release histamine that is a natural chemical that causes itching, redness and swelling of the skin.   In most cases, hives appear and can reappear suddenly – within several hours.

Skin appearance:  Hives can occur anywhere on the body and actually appear and disappear and give the appearance that the rash is actually moving around the body.  They are raised areas of skin that itch and these red areas may enlarge and merge together.  The itching is usually the most bothersome symptom and it can be severe enough to interfere with work or sleep.

Angioedema:  Some people who get hives also have puffiness of the face/lips, eyelids, mouth, hands, feet and genitalia.  Swelling usually affects one side of the body more than the other and may give the sensation of fullness or discomfort in the area of swelling.

Anaphylaxis:  Hives can occur as part of a serious allergic reaction called Anaphylactic shock.  You should see a medical provider right away if you have symptoms along with hives such as:

1)   Trouble breathing

2)   Tightness in the throat

3)   Nausea/vomiting

4)   Cramping or abdominal pain

5)   Passing out

6)   Dizziness or light-headedness

Types of hives:  Hives are usually classified based on how long they’ve been present.  Acute (brief) hives, vs. chronic (long-standing) or physical (triggered by a physical stimulation such as sun exposure or cold).

Acute hives:  These are the type that we see most often in the medical clinic.  They usually don’t last beyond a few days to a week or two.  Triggers that can cause acute hives include:

1)   Infections:  Viral infections actually have been found to cause more than 80% of the cases of hives in children.  The hives usually last a week or two.

2)   Medications:  Many different kinds of drugs can cause hives including nonsterioidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen or Aleve.  Antibiotics can also cause hives, as well as narcotic pain medication such as morphine or codeine.

3)   Insect stings:  Stings from bees, wasps, hornets or fire ants can cause hives around the sting.  If you get hives all over your body after a sting, this could be sign of anaphylaxis, and you should be seen by a medical provider as soon as possible.

4)   Food allergies:  food-associated hives usually occur within 30 minutes to an hour after eating the food.  Common foods which can cause hives include milk, eggs, peanuts or other nuts, soy, wheat, fish or shellfish.

5)   Physical contact:  After you touch a certain substance that you are allergic to, you may get hives.  Common substances that can cause hives are plants, raw fruits and vegetables, latex (found in balloons, certain gloves, condoms, etc.)

Chronic hives:  Many people have hives that occur daily or almost every day.  We call hives that last longer than 6 weeks chronic hives.  Sometimes they can even last for years.  Hives are frustrating and can effect how you look but it is important to remember that hives are not contagious, they are rarely permanent, they are not life-threatening and symptoms are treatable in most people.

For most people who get chronic hives, the cause is unknown.  Chronic hives can be a sign of other medical problems including thyroid or liver problems, chronic infection or lupus.  People with these problems usually have symptoms other than just hives however.

Physical hives:  Hives can be triggered by exposure to cold (they often appear as the skin warms up), changes in body temperature or sweating, vibration, pressure, exercise, sunlight or water.  Some people can develop reddened, raised lines if the skin is stroked firmly or scratched.  This is called dermatographism.

Diagnosis:  Most people do not need testing. The diagnosis can be made by the medical provider by taking a history and performing a physical examination.  Sometimes testing is done if symptoms are not resolving within six weeks.  Skin testing may be ordered by an allergist to test for food and medication allergies.  Blood tests can also be performed to look for other underlying medical problems.  A skin biopsy is a small sample of skin that is removed and examined under the microscope.  The biopsy can sometimes be helpful for patients who have chronic hives and it is usually performed by a dermatologist (skin doctor).


1)  Avoid the cause/trigger.  Many times the cause in not found and the hives usually disappear over days or weeks anyway.

2)  Antihistamines – there are two types of antihistamines.  The older type such as Benadryl often work well, but can cause drowsiness, and are usually taken multiple times per day.  The newer types of antihistamines such as Zyrtec, Claritin or Allegra have fewer side effects are usually taken only once or twice a day.

3)  Oral steroids such as prednisone at a high dose are often used in combination with antihistamines.  We are careful with the use of steroid medications because long-term use can cause serious side effects if taken of long periods of time (months to years).

4)  Topical steroids or creams:  Sometimes topical creams may help with the itching, however we usually don’t use topical steroid creams on the hives because the rash may move from one area of the body to another rapidly.

This document is for informational purposes only, and should not be considered medical advice for any individual patient.  If you have questions please contact your medical provider.


I hope that you have found this information useful.  Wishing you the best of health,

Scott Rennie, DO



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