Allergy shots are a series of injections given to decrease someone's sensitivity to an allergen. A full course of allergy shots can take up to five years to complete, making it a serious commitment, but it can greatly improve quality of life. For patients with very severe allergies, allergy shots can also be lifesaving, as they allow the patient to be exposed to the source of an allergy without developing fatal symptoms.
Also known as immunotherapy, allergy shots involve introducing very small amounts of an antigen to a patient's body. In the build up phase, in which shots are taken one to three times a week for three to seven months, the amount of the antigen is gradually increased with each shot. The goal is to expose the body without triggering an allergic reaction, allowing the patient's body to recalibrate itself so that it will not longer recognize the allergen as a threat. In the maintenance phase, which requires one shot a month for two to five years, the patient is given regular doses to continue the desensitization.
When allergy shots are given, it is usually because a patient has very severe allergies, or experiences allergic reactions more than three times a year. Patients who find it difficult to avoid an allergen can also benefit from shots, as can patients who have tried other means of allergy control which turned out to be unsuccessful. Immunotherapy is not recommended for people with heart conditions or severe asthma, or for pregnant women.
Insect allergies, seasonal allergies to things like ragweed, and indoor allergies can all be treated with allergy shots. Food allergies cannot. Before offering allergy shots to a patient, a doctor will usually conduct an interview to collect information about the patient's history and current medications, to make sure that he or she is a good candidate for the shots. In certain cases, a doctor may recommend rush immunotherapy, in which the patient gets increasingly large doses every few hours in a controlled environment like a hospital for rapid desensitization.
Typically, patients are asked not to exercise for at least two hours before and after allergy shots. They will also need to stay for monitoring for at least 30 minutes after a shot to confirm that no adverse reactions are occurring. Allergy shots are not risk free, and patients can sometimes develop allergic reactions and other serious responses, which makes this monitoring period important. If a patient does start to feel strange after a shot, he or she should report the feeling immediately so that medical care providers can take action.