By Dr. Harold Nelson
Allergy shots, or immunotherapy as it is called among allergists, is a form of treatment that has been shown to be effective for treating allergic rhinitis, also known as hay fever, and allergic asthma. Unlike the pills and sprays that are used to treat allergic rhinitis and asthma, allergy shots involve a commitment usually of 3 to 5 years, with the full benefit coming only to those who complete the course of treatment. Therefore, the decision to begin allergy shots is one that should be made only after considering its advantages and disadvantages.
The basic principle is that we begin with smaller amounts of the allergen and begin to recondition the immune system to stop producing IgE antibodies, which result in allergic symptoms, and produce benign IgG antibodies instead. The serum must be high enough in allergens initially to stimulate an immune response–in spite of claims homeopathic levels just won’t do—and that is why such treatments should be done with medical supervision. Gradually, the dosages are increased.
If your child has nasal allergies, particularly those that recur at certain times each year, many studies have shown that the improvement in symptoms with allergy shots is greater than that with antihistamines or nasal sprays. Furthermore, after a course of 3-4 years of shots, it is possible to stop the treatment with few or no symptoms for a number of years. Results have been shown to persist when patients were reexamined 10 years after stopping the shots. Improvement may persist for a lifetime, but studies have not been conducted to examine that duration of effect. It is not only the nasal symptoms that are improved by allergy shots; studies have shown that the likelihood of the child going on to develop asthma are also reduced by more than 50 percent. The disadvantage of allergy shots for seasonal nasal allergies is that the treatment continues throughout the year and involves visits to the doctor’s office on a weekly basis for several months, followed by less frequent visits for 3-4 years. Thus, if the response to antihistamine pills and nasal sprays is satisfactory and the season is short (one or two months) the added benefit of allergy shots may not outweigh the inconvenience involved. On the other hand, the allergy shots are the only treatment offering the possibility of a cure, whereas antihistamines and nasal sprays may be required for many decades. Immunotherapy is also very cost effective—with overall cost declining steeply after that, versus the perpetual costs of antihistamines and other medications. However, the real payoff is in improved quality of life, and better performance at school.
Asthma has an even greater potential for interfering with a normal lifestyle and resulting in serious illness. However, not all asthma is caused by allergies and therefore the response of asthma to allergy shots will depend on the contribution of allergy to the symptoms in each individual case. This can only be determined by a careful history taken by a person with special interest in allergic diseases and by performing testing to detect sensitivity to environmental exposures. If it is determined that allergies contribute significantly to a child’s asthma, and if the asthma requires daily medication or interferes with normal activities, most allergists would recommend allergy shots to the offending exposures. A problem with allergy shots, in addition to the inconvenience of the visits to the doctor’s office to receive the shot, is that some patients will have reactions to the injections that can vary from hives, to breathing difficulties, to collapse and even death. Fortunately the very severe reactions are largely limited to patients with asthma that is not well controlled. That means, however, that if your child has asthma and begins allergy shots, it is very important that he/she be very faithful in taking their prescribed medication to ensure that the asthma remains well controlled while they are receiving the allergy shots.
Should your child receive allergy shots? Clearly this is an important decision and one that should be discussed on an individual basis with your allergists.
Dr. Harold Nelson is board certified in Asthma and Immunology and Internal Medicine. He graduated from Harvard College and Emory University Medical School, and trained in Allergy and Immunology at the University of Michigan. He spent 30 years in the United States Army and is currently Professor of Medicine at National Jewish Medical and Research Center in Denver.