Nasal congestion is usually due to inflammation of lining in your sinuses, often caused by allergic reactions or a symptom of the cold/flu. When allergy medication fails to alleviate congestion, your doctor may offer immunotherapy as a treatment option. Immunotherapy consists of allergy shots that desensitize your body from allergens through monthly injections until symptoms subside. According to Alan R. Hirsch, author of "What Your Doctor May Not Tell You About Sinusitis," treatment can last from three to five years, and afterward you should no longer have allergies.
The build-up phase is the initial phase of treatment that allows your immune system to become sensitized to the allergen, according to the Mayo Clinic. This phase can last between three to seven months, and requires getting a shot one to three times weekly. According to Hirsch, as the weeks progress the dose increases to build up tolerance. Your doctor may increase the dose and the number of times you receive a shot to speed up the build-up phase. According to the Mayo Clinic, you will shave off time for the initial phase, but you are at a higher risk of developing adverse reactions from the shots. You should not receive these shots if you are already pregnant, according to Hirsch.
After the build-up phase is over, your doctor will administer a dose of the allergens on a monthly basis to maintain the effectiveness of the shot. You must receive these monthly shots for the entire time period of three to five years to keep allergy flare-ups in check, according to Hirsch. Allergy shots are effective against: grass, tree and weed pollens, as well as mold spores, cat dander and insect stings.
The side effects of allergy shots include swelling and redness where the shot was administered. After receiving the shot, you may experience bouts of sneezing, wheezing or hives. According to the Mayo Clinic, in extreme cases you may also experience throat swelling and chest tightness. If this occurs, it is important to contact your doctor immediately or go to the emergency room. Before receiving an allergy shot, your doctor will apply an allergy test to your skin to determine what allergens affect you the most. This is conducted by slightly scratching your skin with a needle that contains the allergen on it, followed by waiting 20 to 30 minutes for an allergic reaction.