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Allergy Shots (cont.)

Do the Shots Have Side Effects?

Generally, allergy shots are safe, with minimal side effects. There are no long-term complications associated with this form of therapy, but there is a small risk of allergic reactions immediately following the injection. These allergic reactions can be severe (see below). Typically, allergy shots may cause slight swelling or redness at the injection site. These reactions can occur immediately after the injection and/or can occur several hours later. This mild allergic reaction is usually harmless and goes away within 24 hours.

The shots may also cause symptoms similar to the allergy symptoms you experience: itchy, stuffy nose; itchy, watery eyes; sneezing. In very rare cases, these symptoms become very severe and are accompanied by other symptoms, including the following:

  • Difficulty breathing or wheezing
  • Chest or throat tightness
  • Rapid or irregular heart beat
  • Dizziness or light-headedness
  • Loss of consciousness
  • Death
This type of very severe allergic reaction is known as anaphylaxis.
  • It is a very uncommon reaction to an allergy shot, but it is dangerous, even life threatening.
  • This is less likely to happen if you follow the schedule of shots recommended by your allergist and observe the technician administering the shot. Be sure you are receiving the correct dose of the correct extract.
  • The dizziness, light-headedness, and loss of consciousness are due to dangerously low blood pressure, usually called "shock." These symptoms occur when the brain is not receiving enough blood.
  • Anaphylactic shock is a medical emergency.
Such severe reactions usually begin within 20-30 minutes after receiving the shots. For this reason, most allergists require that you wait in the office for 20-30 minutes after your shots to be monitored. If you should experience these symptoms at any time, tell the allergist or other medical professional right away.
  • If you have already left the allergist's office, and are having a severe reaction, go directly to the nearest hospital emergency department. If you already have and Epi-pen, use it. If you have an antihistamine such as Benadryl, take it regardless, go to the nearest hospital emergency room or urgent care center as soon as possible.
  • Do not attempt to drive yourself. If no one is available to drive you immediately, call 911 for emergency transport.

Medically Reviewed by a Doctor on 12/1/2014
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