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An allergic reaction to allergy shots is quite common, but many of the symptoms are quite mild. Most patients who get allergy shots will experience mild versions of their regular allergy symptoms, including runny noses and watery eyes. Swelling on or around the injection site is also quite common. A severe reaction, however, can sometimes result in anaphylactic shock. If the throat swells, it will cause breathing difficulties or possibly death.
Allergy shots are very similar to vaccines and contain small amount of allergens, substances to which a person may be allergic. When these allergens are injected into the body, the immune system produces antibodies, but not nearly as many as it would under other circumstances. Over time, the idea is that the body gets used to the allergen and stops reacting to it. In the meantime, however, nearly everyone has an allergic reaction to the shots.
Many times, people experience the typical allergy symptoms after getting a shot. For example, if a person experiences watery eyes and nasal congestion when exposed to pollen, he will often experience these symptoms when getting a shot for this allergy. These symptoms are typically very mild, however, and they will usually last no more than a couple of days. An oral antihistamine can help reduce the reaction.
Local skin reactions, like swelling and redness around the injection site, after an allergy shot are not uncommon. These symptoms can begin either immediately after allergy shots or several hours later. Like the other symptoms, they are typically minor and will often go away quickly.
A more severe reaction to allergy shots can include anaphylactic shock, which can cause a drop in blood pressure. If this occurs, a person may feel dizzy or lightheaded and possibly faint. A rapid heartbeat may also occur during a severe allergic reaction. Some people may experience severe swelling of the face and surrounding areas, including the eyes, lips, or tongue. Swelling of the throat can constrict the airways, causing breathing difficulties.
Treating an allergic reaction to allergy shots is very important since, without the proper treatment, a person could die. Patients who get allergy shots are usually required to stay in an examination room or a waiting room for up to an hour afterward. This gives medical professionals an opportunity to observe them for any adverse reactions. If this occurs, an epinephrine (adrenaline) injection may be necessary to reverse these side effects.