Allergy & Immunology

Pollens

Seasonal allergic rhinitis, often referred to as hay fever, affects about 10% of the U.S. population. Substances called allergens cause this seasonal allergy, and the most common allergen is pollen. A wide variety of trees, grasses and weeds release pollen from the spring through the fall, causing symptoms such as runny nose, sneezing, itchy watery eyes, cough and more. Depending on where you live, you might be allergic to different pollens at different times of the year.

Molds

There are thousands of types of molds, but only a few are recognized as as a cause of allergies. The spores, or reproductive parts of the mold, are carried in the air and can cause allergy symptoms in some people.

While not seasonal, molds are affected by wind, rain and temperature. They typically flourish in moist, shady outdoor areas and in damp basements, bathrooms or closets inside homes.

Dust Mites & Cockroaches

A dust mite is a microscopic organism found in all homes and workplaces. House dust mites live in bedding, upholstered furniture and carpets. Certain proteins in the mites and their waste products provoke an allergic reaction in some people.

In a similar way, proteins in the saliva and waste products of cockroaches are also known to be allergenic. All of these allergens are carried by the air and, when breathed in, can trigger a reaction.

Animal Allergies

Allergies to animals are a common cause of rhinitis and asthma. Household pets (most often cats and dogs) are the main cause of animal allergies, but other animals are also frequent triggers. This includes rabbits, horses and rodents such as rats, guinea pigs and hamsters. Allergy-causing proteins from animals are often found in public places — such as schools or offices — where animals are not normally permitted. These proteins, or allergens, stick to people’s clothing and shoes. They contaminate indoor areas as the person travels from place to place.

Dander is the skin that flakes off cats and dogs. These small, airborne particles can cause allergic symptoms when inhaled into the nose or lungs. They can also trigger allergic reactions after coming into contact with the mucous membranes of the nose, throat or eyes.

Saliva from pets may also be a source of allergen. Some people develop hives when licked by dogs. Rodents shed protein in their urine, which can be very allergenic. The urine becomes aerosolized and stays airborne for long periods of time.

Unfortunately, all cats and dogs can cause humans to have allergenic reactions. Some smaller species of dogs may shed fewer allergens indoors than large, hairy dogs such as a Labrador or German Shepherd.

Drug allergies occur when the body responds to the modified or unusual proteins in certain medications. Symptoms can appear at any time — from within a few hours to a couple weeks.

Allergies to medications account for up to 10% of all adverse drug reactions. Skin responses such as hives are the most common symptom, but a life-threatening anaphylaxis condition also can occur.

According to the National Institutes of Health, penicillin is a common cause of drug allergy. Research shows that although many people are labeled as being allergic, most people outgrow their penicillin allergy over time. Our providers can evaluate you to find out if you have outgrown your allergy. In many cases, patients are able to use penicillin again without difficulty. This may also be the case with other common antibiotic allergies.

Please tell your Lahey physician about any known drug allergies and any unusual symptoms you have after taking a new medication.

A food allergy results when a person’s immune system overreacts to a food that is usually harmless. Symptoms might include hives, swelling, vomiting, difficulty breathing, throat constriction and/or a loss of consciousness.

In adults, the most common foods that cause allergic reactions include:

• Shellfish such as shrimp, crayfish, lobster and crab
• Peanuts
• Tree nuts such as walnuts
• Fish
• Eggs

In children, the most common foods are slightly different. Foods that most commonly cause reactions in children are:

• Eggs
• Milk
• Peanuts

Adults usually do not lose their allergies, but children sometimes outgrow them. Children are more likely to outgrow allergies to milk or soy than to outgrow allergies to peanuts, fish or shrimp.

Many people confuse food intolerance with food allergy. Different from an allergy, an intolerance doesn’t involve your immune system. For example, you may have uncomfortable abdominal symptoms after drinking milk. This reaction is most likely caused by a milk-sugar (lactose) intolerance. To learn if your condition is food intolerance or a true allergy, your Lahey allergist will take a careful look at your medical history and perform either skin or blood allergy tests.