What Is In Allergy Shots?

A patient’s father recently asked me an insightful question about allergy immunotherapy. Allergy shots had been recommended for his son to treat his seasonal allergy and asthma symptoms and he wanted to know how we decided what allergens to include in the serum.

In some cases, as I explained, the answer is fairly straightforward. If his son had year round allergy symptoms that worsened when he was home on weekends, a very strong reaction to cat dander on allergy testing, and lived in a home with six cats, desensitizing to cat would definitely be a high priority.

More often, the decision is a little more involved but we start with the  following questions:
1. What is the patient sensitive to on allergy testing? When we read an allergy test, a positive reaction is defined as an increase in wheal size (raised area) of 3 mm or greater compared with a negative control or redness around the test site of 10 mm or greater. Skin test reactions are often much larger, however for an allergen to be considered clinically significant, it only has to reach the minimum size.

2. Is the patient currently exposed to the allergens that show positive on the allergy test?  The answer to this can be a bit tricky. For example, a number of people show positive reactions to House Dust Mite on allergy testing. And yet, most experts agree that House Dust Mite levels in the typical Arizona home are too low to cause significant symptoms. This is because House Dust Mites need an indoor humidity level of at least 50% for most of the year to thrive and the majority of homes in the Phoenix area rarely have indoor humidity levels this high. When there is a question, a simple test is to measure the indoor humidity levels in various rooms in the home with an inexpensive hydrometer. Unless the hydrometer readings are above 50%, we may not need to include Hose Dust Mite in the serum mix. However, if a patient frequently travels to more humid climates (anywhere but the South Western United States) and has increased symptoms on these trips, treatment for House Dust Mite may be recommended.

House Dust Mite

House Dust Mite

Why would you react to an allergen on an allergy test if you are not exposed to it?   There are several possible explanations. Your allergic sensitivities  may have developed when you were living in an area where the allergen is more prevalent. For example, if you lived in New Orleans for a number of yeas before moving to Arizona, you might have a strong sensitivity to House Dust Mite on an allergy test because of the high level of mite exposure on the Gulf Coast, but mites would be an unlikely cause of allergy problems in your new home in the desert. Cross reactivity is another reason that you may show a positive test to an allergen that you  have never been exposed to.   For example, the major allergenic protein in House Dust Mite is also found in a number of other insects and is also present in the muscles of  shellfish. If you are allergic to shellfish, you may show a positive reaction to House Dust Mite on testing, even though you have never lived in an area where dust mites are prevalent.

Cat and dog dander exposure is another issue. Several studies have shown that animal dander in school classrooms and work places may reach levels high enough to cause allergy symptoms in sensitized people, even if they do not have pets. It is also possible to bring enough dander home from school or work on your cloths for levels in your home to reach symptom-causing levels!

You can have pet dander without having a pet

You can have pet dander in your home without having a pet

3. Can the allergen be avoided or eliminated from the environment? If a patient has significant allergy problems caused by an indoor pet and that is the only thing they are allergic too, relocating the pet from the home might be the best solution.   This is certainly true in principle but relocating a family pet from the home is frequently not an option and so management with allergy injections may be the only long term solution.

4.  Is the allergen available for immunotherapy? If you developed allergy problems soon after bringing home a pet llama from your travels to Machu Picchu, appropriate material for desensitization may not be readily available.  Because of cost restraints, the companies that provide the material for making allergy immunotherapy extracts limit choices to items that are frequently used.  Even though Phoenix is the 5th largest city in the US, the percentage of people that are exposed to the unique allergens of the Sonoran Desert is small compared with other regions.  For this reason, some allergens that may be important for those living in our area may not be available. For example, Palo Verde, the state tree of Arizona, is not generally available for allergy immunotherapy. What goes into allergy shots 2

Ahwatukee Oak Alley

I attended medical school in New Orleans.  Along with great food, music and the rich culture and history, one of my fondest memories was the magnificent Southern Oak trees.

These ancient giants, some dating back to the Civil War, with trunks the size of a Volkswagen beetle, hanging with moss, framed an idyllic image of the old south.  They are beautiful trees but they are also one of the major causes of spring allergy problems throughout the south.

When I moved to Arizona and started an allergy practice, I was sure of one thing:  I would not have to worry about Southern Oak allergy problems in Phoenix!

I was wrong.

I have known that there are several varieties of Oaks native to Arizona, the majority of which live at higher elevation in the state, and rarely in Phoenix.  But certainly, there were no trees resembling the Oaks I knew from the south, growing in a typical, low water use, desert landscaped yard in Ahwatukee!

Souther Oak Trees Lining Lakewood Drive in Ahwatukee

Oak Tree Pollen

And yet, if you take a drive around the lakes of Lakewood, in Ahwatukee, (as I did on my bike a few weeks ago), you will find the entire seven mile stretch lined with mature Southern Oak trees.  No hanging moss or women in antebellum dresses swinging on porch swings, but most definitely full of pollen.

If You Are Sneezing in Ahwatukee and It’s February – It’s the Ash Trees!

I was visiting a friend last week who lives next to Altadena Middle School. He has two very large, stately trees in his back yard that provide great shade during the summer. In February however, there are no leaves on the trees. Just packets of pollen clusters. The branches are heavy with them.

Ash Flower

Ash Tree Flower








These Ash trees also line the sports fields of Altadena. And once you start to look for them, they are everywhere: in local parks, schools, green belts, and your neighbors yard. All heavy with the same pollen sacks. I took a few pictures while riding my bike and found a large number of Ash trees in Vista Canyon Park next to Desert Vista High School.

Flowering Ash Trees, Vista Park, Ahwatukee, Phoenix

Flowering Ash Trees, Vista Park, Ahwatukee, Phoenix








Interestingly, the logo for the Phoenix Parks and Preserves Initiative is an Ash leaf !

Ash Leaf Logo

Phoenix Parks and Preserves Ash Leaf Logo








More than half a century ago, tree pollen counts in Phoenix skyrocketed. The culprit, the popular Olive tree. From an allergy standpoint the Olive tree is a monster. March through May, Olive pollen fills the air and is incredibly sensitizing with many new residents becoming allergic after just one season of exposure.

So notorious is the Olive for causing allergy problems that it has been banned in a number of cities including Tempe and Phoenix and so you will not see many in the newer communities in Ahwatukee. Unfortunately, the Olive happens to have a close allergy cousin, the Ash tree. Most people who react to Olive on allergy testing will also react to Ash, a form or cross-reactivity. Some allergy-control progress may have been made in limiting Olive tree planting, but this progress has likely been lost in the rising popularity of the Ash tree.

“My Worst Allergy Spring Was the Winter I Just Spent in Arizona”: Part Two

Arizona Ash Flower

While walking my dog several weeks ago, I noticed something unexpected; a number of ash trees in full bloom.   This was unexpected because it was the first week of February and ash trees usually pollinate later in the month.  It was also unexpected because this was near a school in the Foothills of Ahwatukee were the ash trees are supposed to be of a less allergenic variety.   This is in distinction from the Arizona Ash, Fraxinus velutina, which is notorious for it’s prolific production of allergenic pollen. For this reason landscapers have been discouraged from planting Arizona Ash trees for a number of years although they are very numerous in older communities such as the Warner Ranch area as well as old Ahwatukee and Tempe.

Ash trees are in the same family as olive trees, possible the most allergenic tree in Phoenix, and so people who are allergic to one will be allergic to the other

So the ash trees are pollinating a full two to three week early this year, probable because of the warm weather.  This along with large amount of Arizona Cypress and Juniper pollen in the air is creating a very difficult winter for people with allergies.

“My Worst Allergy Spring Was the Winter I Just Spent in Arizona”

When we think of allergy season, fall and spring comes to mind, but not so much winter.  Yet this December, January, and now into February, patients have been coming into our allergy clinic in the suburbs of Phoenix complaining of some of the worst allergy symptoms all year.  Typical complaints include sneezing, itchy nose, and particularly, very itchy eyes.

Alligator Juniper

Alligator Juniper Payson, Arizona

When patients undergo testing for allergies, many show sensitivity to a number of different allergens such as plant pollen, mold, foods, and animal dander.  However, in the case of the winter allergy sufferers, the majority show sensitivity to only one thing: juniper, or more specifically, Cupressaceae.

The Cupressaceae are a family of evergreen conifers found throughout the world. Arizona is home to a number of native species of cupressaceae including Rocky Mountain Juniper (Juniperus scopulorum), Utah Juniper (Juniperus osteosperma), One Seed Juniper (Juniperus monosperma), Alligator Juniper (Juniperus deppeana) and Arizona Cypress (Cupressus arizonica).

Although Phoenix has a number of ornamental varieties of Cupressaceae used in landscaping, the majority are found at 3000-7000 feet elevation and cover millions of acres surrounding Phoenix on all sides.    When conditions are right, a large amount of cupressaceae pollen finds its way into the valley.  One of the chief offenders is Arizona Cypress which is very prevalent in the higher areas surrounding the valley and produces  pollen November through March.

The pollen produced by the different varieties of Cupressaceae cross react with one another, which means that if you are allergic to one you will be allergic to all.  Mountain cedar (Juniperus ashei) is the leading cause of respiratory allergy in South Texas and affects so many with severe allergy symptoms that it has been given it’s own diagnosis, “cedar fever” .

New Immunotherapy Tablet for Grass Allergy: Phoenix Residents Should Read the Fine Print

Last month, the Allergenic Products Advisory Committee  of the Food and Drug Administration (FDA) voted to approve two sublingual allergy immunotherapy  products.  The FDA will need to give final approval, but this typically follows the advice of its advisory committees.   Both products contain a mixture of pollen from several different grasses commonly found in Europe and the United States.

These would be the first FDA-approved forms of sublingual allergy immunotherapy available in the US.  This is good news because the current use of sublingual immunotherapy is unregulated and therefore of undetermined safety and efficacy. And (often of more importance to patients) sublingual immunotherapy is not covered by insurance.

The bad news is that Arizona is not like Europe (at least from an allergy point of view), nor is it like most of the United States either.  It’s hot and dry. Very hot and dry!  Too hot and too dry for most grasses to survive without constant watering making them too expensive to grow.  The exception to this is Bermuda grass.  Bermuda grass is a heat and drought tolerant grass that has become THE landscaping grass in Arizona.  If it is green and growing on the ground in Arizona during the summer it is Bermuda grass.

Bermuda grass is also very allergenic.  It’s affect on allergy sufferers is so great that a Phoenix ordinance requires that grass lawns and fields be cut short to limit pollen production.   The majority (if not all) of the school playgrounds and sports fields in Phoenix are planted in Bermuda grass which means that kids are particularly vulnerable to grass pollen allergy.   It causes nasal and eye allergy symptoms late spring through fall and is often the trigger for severe allergic asthma attacks.

As important as Bermuda grass is for Arizona allergies, the new grass immunotherapy tablets do not contain Bermuda grass.  Many grasses are grouped into families that produce what are called “cross reacting” allergens.  In other words, even thought the grasses have different names and appearance, our immune system reacts to the pollen as though they were from the same, or very similar, plant.   Bermuda grass however does not have any important close cousins, so none of the pollen in the new grass tablets will help to alleviate symptoms causes by Bermuda grass.

And so. Good news:  A grass pollen tablet for allergies may be approved by the FDA.  The bad news:  It will not benefit you if you live in Arizona.

A Not-So-Nice Easter Rabbit

Rabbit Bush (Ambrosia deltoidia), flowering

It’s an unusual name for a weed: Rabbit Bush.  And although it is not clear where the name for this Arizona native variety of ragweed comes from, one thing is clear:  there is a lot of it and it’s a major cause of allergy problems in the spring.  In fact, Rabbit Bush is one of the most prevalent spring allergenic weeds in South Mountain Park and is therefore a significant source of ragweed pollen for Ahwatukee and surrounding areas.   Rabbit Bush (technically Ambrosia (Franseria) deltoidea and also known as triangle bur ragweed or tirangleleaf bursage) comes to life in the spring, particularly if we have had winter rain, producing copious amounts of pollen in the Arizona Sonoran desert from March until  May.   Allergenically,  it is closely related to other varieties of ragweed found throughout the Unities States and will trigger allergy symptoms in patients who have had problems with ragweed before moving to Phoenix.   Other native varieties of ragweed found in the Sonoran Desert include Canyon Ragweed, fond of desert washes, and Desert Ragweed, a smaller but also prevalent ragweed  in the Phoenix area.

Rabbit Bush (Triangular Bursage)

Fall Comes to the Desert

It’s finally starting to feel like fall.  Nighttime and early morning temperatures have dropped below 90 degrees, the monsoon humidity and risk of monster dust storms is on the decline, kids are back in school, and club sports are in full swing.   We are also seeing early signs of the Arizona fall allergy season.   Unlike the Midwest and the South, where fall can bring some of the worst allergy misery of the year, the fall allergy season in the desert can be hit or miss depending on the amount of monsoon rain during the summer.   This year, things are shaping up to be a real hit.  Higher than normal rain fall has produced a bumper crop of allergenic weeds including Russian Thistle (tumble weed), Careless Weed, and Ragweed.  In many parts of the country, ragweed pollen defines the fall allergy season.  In the Phoenix area, ragweed often plays a minor role in the fall allergy season because it is too hot and dry.  On the other hand, ragweed is a major cause of springtime allergy symptoms, particularly when the valley gets sufficient winter rain. This year may be an exception, and residents of Phoenix who usually have allergy problems during the spring may find themselves suffering as much itching, sneezing, and wheezing this September and October as they usually do in March and April.

Bermuda grass, although pollinating throughout the summer, becomes a more serious allergy problem in the fall as children start practicing and playing on bermuda grass sport fields.  Landscapers and homeowners also begin “scalping” and dethatching there bermuda grass lawns in preparation for planting winter rye grass. Scalping a lawn (mowing the grass very close to ground) sends a cloud of bermuda grass dust high into the dry fall air where it can be carried throughout the neighborhood.

All this increase in atmospheric pollen and particulate production is compounded by the phenomenon of temperature inversion.  In the fall, as the nighttime temperatures begin to drop, a layer of cooler air becomes trapped by a layer of warmer air above. Particulates, including dust and pollen, become trapped in this cool air mass close to the ground,  right at nose and mouth level.

Patients with asthma often have a harder time keeping under control during the fall.  This is not only the result of increased fall pollen and air pollution exposure but also because of the fall cold and flu season.  Viral upper respiratory infections are the number one cause of asthma attacks, particularly in school age children.

Palo Verde (Parkinsonia microphylla)

Untitled design (10) (1)Palo Verde is one of the most common trees of the Sonoran Desert and is found throughout southern Arizona and southeastern California.  Starting in April, the Palo Verde produces a brite yellow flower that stands in contrast to it’s characteristic  green trunk and branches.  In late spring it is common to see the Palo Verde covered in yellow blossoms with a blanket of yellow at it’s base from dropped flowers.  It is this fact that makes the Palo Verde a bit of an allergy enigma.

As a general principle, plants that produce conspicuous and fragrant flowers do so to attract insects such as bees to distribute their pollen.  In addition, the pollen is typically heavy and sticky so that it sticks to the insects rather than being wasted blowing in the wind.  Wind pollenated plans on the other hand produce copious amounts of light pollen that easily catches a ride in a breeze, and often finds it’s way to the nose and eyes of allergy sufferers.   Palo Verde, although an insect pollenated tree, can cause allergy problems just because of the huge volume of flowers that fall to ground, dry, and then picked up by the wind

Arizona Ash Attack

A bit of bad news if you live in Tempe, Arizona, particularly if you live in or near Warner Ranch,  and are allergic to Ash pollen.

Arizona Ash is a medium to large deciduous tree, growing to 30-50 ft and found natively in Arizona around the Mogollon Rim at an elevation of 2000-6000 ft.  In contrast to the more common varieties of desert trees, such as Mesquite and Palo Verde, that to some look more like large bushes trimmed to look like a tree, the Arizona Ash provokes memories of the kind of stately shade trees found in the Midwest or Northeast, where many migrants to Arizona grew up.

I have heard that homeowners originally buying into the equestrian homesites in Warner Ranch (between Elliot and Ray Road and east of Ahwatukee) in the 80s were strongly encouraged, if not required, to plant an Arizona Ash tree.  The result is an area filled with mature Ash Trees.  The Ash trees began to pollenate around the first of February, a bit early this year, likely because of the warm, sunny weather. When the wind blows there will beenough Ash pollen in the air to affect the surrounding areas of Tempe, Chandler, and Ahwatukee for several weeks to come.