All About Allergies (video)

What causes allergies and how to reduce allergy symptoms

What causes allergies and how to reduce allergy symptoms

Itchy nose? Irritated eyes? Scratchy throat? Sounds like you may have allergies or allergy symptoms — and you’re not alone. According to the Centers for Disease Control and Prevention, allergies account for nearly 17 million doctor visits each year.

In this video, San Diego Health host Susan Taylor talks with Ronald Simon, MD, an allergist and immunologist at Scripps Clinic in Carmel Valley, about what causes allergies, allergy symptoms and how to find relief.

What is an allergy?

A true allergy happens when the body’s immune system reacts to something that bothers it, called an allergen. Often, people think they have allergies when they really don’t. Instead, the cause may be:


While people may be irritated by something like cigarette smoke, it’s not an allergy unless the immune system is involved.

“If there is enough smoke, everybody is going to react to it,” says Dr. Simon. “But an allergy happens when something like a flower or an animal that is a natural substance, and should be harmless in a medical sense, triggers an immune system reaction.”


Some people also mistake intolerances for allergies. Someone with lactose intolerance, for example, may get terrible cramps from milk because they lack a digestive enzyme, but they do not have a true dairy allergy.


Both allergies and colds can involve sneezing, coughing and sore throat. However, an allergic reaction signals the immune system to release histamine, which causes itching. If your nose or eyes itch, it’s likely an allergy.

People may develop allergies to just about anything, but two of the most common categories are airborne allergens and foods.

Airborne allergens

These are substances in the air that can affect your eyes, nose, throat and respiratory system, such as pollen, grasses, flowers, animal dander and dust mites.

“Most people who are allergic to dust are really allergic to dust mites, which are microscopic living creatures that like to eat dead, flaky skin,” says Dr. Simon. “They live in pillows and mattresses and other places where dead skin collects.”

Similarly, people are usually not allergic to animal dander, but to the saliva that gets on the animal’s fur and sheds in the dander.

Allergy symptoms depend on how your immune system reacts to the offending substance. Symptoms of airborne allergies may include:

  • Itchy or watery eyes
  • Itchy or running nose
  • Sneezing
  • Congestion
  • Headache
  • Scratchy or sore throat
  • Coughing


The most common food allergies include wheat, soy, milk, eggs, shellfish, peanuts and tree nuts.

“Fortunately, outgrowing some food allergies happens very frequently,” says Dr. Simon. “Wheat, egg and soy are among the most common food allergies, but you can hardly find an adult who’s allergic to any of those three.”

Allergy symptoms

Depending on the severity of the allergy, symptoms can range from mild to life-threatening and may include:

  • Itching or swelling inside the mouth
  • Upset stomach
  • Nausea or vomiting
  • Cramps and abdominal pain
  • Diarrhea
  • Itchy or swollen skin
  • Hives or rash

In severe cases, people may develop life-threatening symptoms, such as:

  • Swelling of the throat
  • Difficulty breathing

If severe symptoms develop, call 911.

Take control of allergies

The first line of defense against allergies is to avoid the allergen. San Diego’s moderate year-round climate means that some type of pollen is growing most of the time, so avoiding it can be a challenge. Check pollen reports to find out when levels are lowest and schedule outdoor activity accordingly if possible. Use a HEPA air filter to filter out most of the pollen that gets indoors. Dust covers on pillows and mattresses can help with dust mite allergies.

Medication is another defense. Several highly effective antihistamine medicines are now available over the counter at full prescription strength; if you’re congested, choose one with a decongestant added.

“If medication isn’t enough, immunotherapy can help desensitize patients by tweaking their immune system to actually stop it from reacting,” says Dr. Simon. “A steroid shot can take someone through allergy season, or a series of allergy shots can be done to help build up immunity to an allergen.”

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