Immunotherapy (allergy shots): The differences in the Build-Up Phases

Provided by David Hauswirth, MD

What is the difference between immunotherapy (IT) and Cluster immunotherapy?

Immunotherapy (“allergy shots”) is a treatment for allergies.  The patient is given gradually increasing doses of allergen (substance that causes your allergies), trying to make them tolerant or not allergic.  There are typically two phases to immunotherapy, build-up and maintenance.  For any build-up type (traditional, Cluster, etc.), the length of treatment is the same, typically 3-5 years.  The difference between Cluster and traditional immunotherapy is the buildup phase.  

With Cluster immunotherapy, the build-up phase is accomplished slightly more quickly, hopefully reaching a higher dose and relief a little quicker. This is accomplished by receiving a few shots each session and making larger changes in the dose.  With all types of immunotherapy, there is a risk of an allergic reaction when receiving a shot.  The risk with Cluster immunotherapy is slightly higher than traditional buildup schedules.

Cluster allergy shots are different from “Rush” immunotherapy.  “Rush” immunotherapy is an attempt to do the whole buildup in a day or two.  There is a much higher risk of a systemic reaction with this type of treatment.  “Rush” therapy is done when someone really needs to get rapid protection, such as a life threatening venom allergy.

Does Cluster immunotherapy work better than traditional immunotherapy?

Cluster IT is not better, but it may work more quickly.  All build-up programs have the same final result.  The only difference is how quickly you reach the maintenance dose.  A patient on Cluster, a patient on “Rush”, and a patient on traditional immunotherapy will all be on the treatment for 3-5 years and will have the same outcome, regardless of the build-up schedule.  Benefit for any immunotherapy program is based on the time it takes for your immune system to shift away from allergy responses after you reach maintenance.

Is Cluster immunotherapy safe?

Yes.  With all types of immunotherapy there is a risk of anaphylaxis or a systemic allergic reaction.  The faster you increase the dose, the more risk of a reaction.  Therefore, a slower traditional buildup has the lowest rate of reaction.  Cluster buildup has a rate of reaction slight above traditional.  “Rush” immunotherapy has a higher rate of anaphylaxis than either of these other two types.

Does the The American Academy of Allergy, Asthma & Immunology (AAAAI) have statements, either way, about the use of accelerated schedules for immunotherapy?

No system of build-up is endorsed by the AAAAI.  Cluster and rush immunotherapy are used in specific situations when the doctor and patient feel it is appropriate to do so and is safe.  They are not appropriate for everyone.  Very accelerated build-up (“Rush”) is only FDA approved for venom immunotherapy.  This is a specific situation where a rapid push to maintenance is necessary for a life-threatening venom allergy (bee sting). Cluster and rush immunotherapy are not FDA approved and are considered off-label use.  Speak with your doctor if you are interested in more information on immunotherapy.