University Health System Blog

Dr. Kate Martin answers the question: “Are flu vaccines safe for me if I’m allergic to eggs?

If you have had a severe allergic reaction to eggs, such as difficulty breathing or swallowing, then you should not get a flu shot.

The explanation for this comes from the process in which the influenza vaccine is made. The actual viruses used for the flu shot are initially grown in eggs. These viruses are later inactivated, or killed, so you cannot actually get the flu from the influenza vaccine. However, as the origin from eggs never goes away, anyone with a severe egg allergy should not receive the flu vaccine.

Kate Martin, M.D. is an assistant professor of family and community medicine at the University of Nevada School of Medicine in Las Vegas. She practices at the Family Medicine Clinic.

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Dr. Mary Beth Hogan answers the question: “What is eczema and what causes it?”

The medical name for eczema is atopic dermatitis. Eczema is also known as “the itch that rashes.”

About 10 to 20 percent of children will have eczema. Most cases appear in children before their first birthday.

The basic defect first appears as dryness, causing itching, and followed by a rash. High humidity levels may affect the severity of the rash. For instance, eczema may appear worse in the high desert climate of Reno and better in the humidity of the northeast U.S. Applying emollients to the skin may help for this reason.

Eczema typically appears on the face and neck. It could also be found behind the knees, ankles and the inside area of elbows.

There are several factors that can exacerbate eczema. A genetic disposition for eczema is a big factor. A food allergy, especially to eggs, is a common aggravating factor in cases of eczema.

Contact allergens such as cats and dogs, dust mites or mold may also exacerbate eczema.

Finally, skin infections, such as bacteria or yeast infections, may make eczema worse. About 25 percent of patients with eczema will not have an allergy as a cause.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine and University Health System. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “What is the difference between a skin prick test and a RAST?”

Both tests are designed to detect an allergen specific allergic antibody (IgE). This antibody is made by the body’s immune system, and when allergen is detected, a series of events is set-off which is finally expressed as symptoms such as sneezing, itchy eyes, runny nose or even a life threatening reaction such as anaphylaxis.

Diagnosis of allergy is made when detection of allergic antibody is made, and this antibody, when combined with the allergen, could be responsible for the symptoms.

Prick testing is performed when a drop of allergen is loaded onto a plastic device, that when used to prick the top most layer of the skin, results in a very minute localized reaction helping to establish that allergic antibody is present.

This test is no longer performed with a needle, making it nearly painless. Its advantage is that results are known in 20 minutes. In addition, it is far more cost-effective than blood tests. Its disadvantage is that antihistamines such as Benadryl block the allergic reaction from happening and patients must be off these medications for seven days before skin testing. It also cannot be performed on skin with rashes such as atopic dermatitis.

Blood tests are generally known as RAST (radioallergosorbent test) or PharmaciaCAP testing. Its advantage is that it can be performed if the patient has a rash or is on an antihistamine.

Disadvantages of the test are that it can be painful. In addition, the presence of large amounts of allergic antibody can obscure results with this test, making it a little less accurate than a skin prick test.

This problem with false positive results is particularly true with food tests. It is significantly less cost-effective when large numbers of allergens need to be tested as compared to skin tests. There is also a delay in finding out test results compared to skin testing.

Which test is required to diagnose allergy is also decided by your doctor based on what type of allergy is suspected.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine and University Health System. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “What is the difference between food allergy and food intolerance?”

Food allergy is based on the presence of an allergic antibody to a specific food. Because this allergic antibody is present, a classic series of symptoms happens after ingestion of this food.

This reaction includes hives, difficulty breathing, wheezing, difficulty swallowing, vomiting , diarrhea, loss of consciousness and even potentially dying.

This reaction, when it is this severe, is called anaphylaxis and usually occurs within one to two hours of eating the allergenic food.

Milder reactions can occur with either smaller amounts of allergic antibody or smaller amounts of food ingestion. Treatment for this severe reaction is total food avoidance including trace amounts and carrying an epipen in case of severe reaction.

Some people may express problems of atopic dermatitis breakouts when having the allergic antibody and ingestion the problematic food.

A food intolerance involves possibilities other than the anaphylaxis or eczema.

These include lactose intolerance due to the lack of the enzyme that processes the sugar (lactose) present in milk. Bloating, cramping, or diarrhea may happen.

Milk may also cause nasal congestion when it combines with post-nasal drip to make it thicker.

Other people may have gastroesophageal reflux symptoms of pain or the sensation of food going up and down the feeding tube (esophagus) when ingesting the problematic food.

These food intolerance problems are usually dose dependent, meaning small amounts of food may not cause a reaction, but larger amounts of food will.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine and University Health System. Dr. Hogan is based out of Reno, Nevada.

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Dr. Nevin Wilson answers the questions: How can I tell the difference between cold and allergy symptoms? Also should I use a humidifier to help my child breathe at night?

There are several ways to determine if your symptoms are related to a cold or an allergy.

A fever and sore throat, as opposed to one that feels itchy, usually accompanies a cold. Nasal discharge starts out clear, then turns yellow and finally green as the cold progresses.

Allergies are more commonly associated with itchy, red, burning eyes, itchy throat and incessant sneezing.

Those who have allergies are more susceptible to getting colds, which can then lead to sinusitis.

I’m not a big fan of humidifiers because their main purpose is to add moisture to the air. When you do that, you increase the atmospheric conditions of the room or home and make them more favorable to growing mold and dust mites, two of the most common pediatric allergies.

This is especially true in Nevada, where it’s dry.

Dust mites and mold flourish in humidity around 40 percent and it doesn’t take much effort for a humidifier to raise a room’s humidity to that level.

This same argument holds true for using a swamp cooler in the summer: by raising the humidity levels, you increase the chance of developing dust mites and mold which can then affect your child.

Nevin Wilson, M.D., is chair of the pediatrics department at the University of Nevada School of Medicine in Reno. He is board-certified in pediatric allergy and immunology. He graduated from the University of Nevada School of Medicine and completed his residency and fellowship training at the University of California, San Diego.

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Dr. Mary Beth Hogan answers the question: “Why are my allergy symptoms much worse in the morning?”

Symptoms of sneezing, congestion and itchy, runny nose or eyes are frequently worse in the morning for several reasons. One possibility is that you are allergic to something inside your house. Allergens that you “sleep with” such as pets and dust mites are causing allergic reactions as you breathe them in with symptoms then noticed upon getting out of bed in the morning.

In addition, sleeping with open windows and then breathing in pollens that you are allergic to can cause early morning symptoms. This is particularly true for pollens as peak pollen release time from plants occurs between five to ten o’clock in the morning.

Avoidance measure to improve these symptoms include encasing the pillow, mattress and box spring in dust mite proof covers with frequent washing of bed linens in hot water and hot dryer.

Other measures to improve morning allergy symptoms include sleeping with the windows closed and either removing pets from the house or performing special cleaning measures for pet dander removal.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine and University Health System. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “When should I have allergy testing?”

Any age group can be tested and we have seen newborns already allergic to cow’s milk. However, testing should be limited to those allergens likely to be present in that age group. For instance, children less than a year old may be allergic to pets and dust mites, but are very unlikely to become allergic to pollens. Up to 70 percent of children and adults may have allergies which trigger their recurrent wheezing or asthma.

Individuals requiring asthma hospitalizations or have difficult to control asthma should be tested. Infants, children or adults with asthma in the absence of viral infections should also be allergy tested. Anyone with a history of a significant reaction to a food, bee stings or chronic eczema should be tested. Likewise, people with nasal problems and hay fever who respond poorly to antihistamines and topical nasal steroids should be tested.

Going to a physician specifically board certified in allergy will help ensure the proper tests are done. Your primary care physician can help you decide whether allergy testing would be helpful for you or your child.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at University Health System, the clinical practice of the University of Nevada School of Medicine. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “Do allergy shots provide relief from allergy symptoms?”

Allergy injection therapy is a treatment modality in which the allergy patient receives injections of the allergenic substance to which she is allergic.

The allergens selected for treatment are determined by the sensitivity shown on the skin testing and their relationship to the patient’s history. The allergy extract contains only those allergens that cannot be avoided.

Allergy immunotherapy is a specific therapy which treats the basic cause of the patient’s problem—their allergy. It increases their resistance to those allergen to which they are allergic, resulting in fewer symptoms after allergen exposure.

Allergy immunotherapy is used in patients whose allergy symptoms are severe and are not adequately relieved by the use of oral medication and avoidance measures. It may also be used in one whose symptoms are becoming worse each year in an effort to prevent progression to more severe allergic problems.

There is also evidence that allergy immunotherapy performed for allergic children may prevent progression to asthma.

All in all allergy shots reduce medication need by 60 percent and may even get rid of allergy symptoms completely.

Once allergy shots are discontinued, the duration of benefits resulting from allergy shot injections varies from one person to another.

In some people, improvement is permanent. In others, mild symptoms return, but can be controlled with medication. A few patients develop increasing symptoms and require a reinstitution of allergy shots.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “What are the dangers of allergic reactions if I don’t seek medical treatment?”

There is no danger if an allergic reaction is confined to the skin. These reactions can be treated with antihistamines. However, on rare occasions, a highly sensitive patient may develop symptoms of a systemic reaction after allergen exposure.

Symptoms include itching of throat, nose, palms or skin, hives, flushing, feeling warm, dizzy, sneezing, runny nose, coughing, wheezing or chest tightness, nausea or vomiting and diarrhea. If this reaction is not stopped it can progress to difficulty breathing, a drop in blood pressure or even death.

It is not the presence of hives or extreme swelling of the skin or face that is concerning in these reactions, but the presence of symptoms relatable to difficulty breathing—throat closing off or wheezing—and decreased blood pressure—volume loss from vomiting or diarrhea or a direct drop in blood pressure with loss of consciousness—that can result in a fatality.

Studies have shown that survival after a systemic reaction is directly relatable to how quickly epinephrine can be given. So allergists currently recommend that all patients use their epi-pen and go to an emergency room immediately after developing any symptoms of a systemic reaction.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine. Dr. Hogan is based out of Reno, Nevada.

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Dr. Mary Beth Hogan answers the question: “Why do I have nasal itching and sneezing, as well as, coughing and wheezing this fall?”

Weeds and molds are common culprits for respiratory allergy symptoms in the fall. Particular activities which can exacerbate these allergies include raking or jumping in the leaves, and hayrides. These activities are relatable to mold allergy.

Indoor allergies also start making their appearance as the house is closed up for the winter. These allergies can be attributed to mold, dust mite, and pet allergy. Feather bedding and stuffed animals can be reservoirs for these allergens. Dust mite covers can help decrease exposure to these allergens in the bed. HEPA filters can help with mold and pet allergy symptoms.

Do not overlook the possibility of common everyday exposures acting as irritants to cause these symptoms. Cleaning agents and highly scented candles, potpourri, and air fresheners can cause both nasal symptoms of sneezing, congestion, and runny nose along with coughing and wheezing. This is most notable in those patients who have underlying undercontrolled allergy and asthma. These agents are also strong enough irritants to be triggers for patients with no allergies and undercontrolled asthma.

Evaluation for common indoor allergens and degree of asthma control can help pinpoint the source of these triggers.

Mary Beth Hogan, M.D. is professor of pediatrics and section chief  of pediatric allergy, immunology and pulmonary medicine at the University of Nevada School of Medicine. Dr. Hogan is based out of Reno, Nevada.

Have a question? University Health System doctors answer select questions from readers like you.