As the immune system develops, white blood cells and organs of our immune system try to determine what is dangerous in our environment in order to fight off infections from viruses, bacteria, fungus and parasites. In order to do this the body needs to determine which substances are from your own body and which are potentially dangerous sources of infection while ignoring non-threatening substances. When the body recognizes its own parts as dangerous or foreign this is called auto-immune disease (lupus, rheumatoid arthritis, etc.). When we do not adequately develop antibodies to viruses and bacterial we become susceptible to severe infections. When foods in substances in the air are seen as foreign the body often inappropriately tries to defend itself. This is what happens in allergy. Most commonly, trees, grasses, weeds, dust mites, animal danders, molds, foods and insect venoms are the cause. In patients with allergy the body mounts an immune response to certain substances which causes inflammation and production of antibodies (IgE) that bind to mast cells which contain histamine. When exposed to these substances (antigens), their binding to IgE antibodies cause release of histamine resulting in itching, swelling and inflammation. This can occur in the nose, lungs, eyes, and gut.
Allergic symptoms vary depending on what part of the body is affected. Because allergies cause symptoms by inflammation, other disorders can have similar symptoms. Allergy testing a useful tool to help differentiate whether your symptoms are due to an allergic cause. Depending on what you are allergic to, these symptoms may be present year round (perennial) or seasonally. Common allergic symptoms include:
Nose (allergic rhinitis) – itching, sneezing, congestion, post-nasal drip
Lungs (asthma) – wheezing, cough (worse at night), chest tightness, shortness of breath with exercise
Eyes (allergic conjunctivitis) – itching, burning, watering, redness
Gastrointestinal (food allergy) – hives, throat tightness, wheezing/cough, vomiting
Many of these symptoms case be seen with other conditions besides allergy so testing can help differentiate whether your symptoms are due to an allergic cause.
For inhalant allergies options include avoidance, medication and/or immunotherapy. Food allergies are usually treated with avoidance only. Although avoidance sounds good, in practice this can be difficult and time consuming, and improvements in allergy symptoms are modest at best. Medications, usually antihistamines and steroids (anti-inflammatory) are given specifically aimed to control symptoms. Fortunately for inhalant allergies these medications can be given topically in the form of a nose spray, eye drops or inhaler which minimizes systemic side effects. For people with moderate to severe symptoms that interfere with life despite medical therapy, immunotherapy is an option.
Most commonly skin testing is performed. A number of antigens are introduced on the forearms or back. There is minimal discomfort with this as it is not actually a shot. Substances that you are allergic to will develop a wheal (hives) along with redness and itching within 15 minutes. In general this is best, fastest and most cost-effective way to identify what you are allergic to. Some people for a variety of reasons may not be able to have skin testing. In this situation, a blood draw may be performed.
Immunotherapy is the only proven treatment to fundamentally change the disease itself. An incremental increase of the substance you are allergic to, known as an antigen, is given at regular intervals and causes the immune system to become less reactive to that substance. Skin or blood testing is performed to identify allergens you are allergic to. Based off of this it is decided what antigens to treat you with. As with skin testing, there is a small risk of a systemic reaction (anaphylaxis).
Most people after completion of immunotherapy experience a significant improvement in symptoms. Remember that this is only for people that have tried avoidance and medication and without much relief. Immunotherapy has been shown to improve allergic rhinitis (hay fever), asthma, and allergic conjunctivitis (eye allergies). Although it may not completely “cure” the disease, medication use is significantly less and immunotherapy has been shown to prevent or limit new allergies as well as significantly reduce the chance of developing asthma for certain people.
Immunotherapy can be done in two ways. The standard way is by giving weekly allergy shots, know at subcutaneous immunotherapy (SCIT), in the back part of the arm. This is done in increasing dose until your body develops enough tolerance that you can handle fairly strong amounts of antigen without a systemic reaction. When a concentrated dose can be given this is known as being “at maintenance”. Shots are continued and eventually spaced out until symptoms are controlled and injections are given every other week or every month. The entire process takes about 3-5 years. Fortunately after you have achieved tolerance and stop treatment there are long-term benefits which usually last for years or occasionally a lifetime.
Sublingual immunotherapy (SLIT) has become an increasingly popular option for many people. Instead of shots, drops of antigen are placed underneath the tongue daily. This is very commonly done in Europe and increasing in the U.S. with results similar to allergy shots (SCIT). The advantages of SLIT are that they can be done at home because it is safer and no shots are needed. Unfortunately this treatment is not yet FDA approved and therefore not covered by insurance. We offer this service at a reasonable price for the benefit of our patients, typically between $50-100 per month depending on what you are allergic to. Remember the overall cost with this treatment may not be more expensive when you factor in time lost due to doctors visits for shots, co-pays and the cost of allergy medications which usually lessens with treatment.
For select patients there are FDA approved sublingual tablets for grasses and ragweed. These may be an option for people who are allergic to only certain types of grasses for example. If you have significant allergy to several types of antigen, this is probably not the best option. However since these tablets are FDA approved, they are covered by most insurances.