Uses, Benefits and Side Effects of Immunotherapy

Immunotherapy Overview

Immunotherapy is an effective method, used as a preventive treatment for both chronic and seasonal allergies. It is a type of biological therapy in which small doses of allergens, the substance that a person is allergic to, are given to the patient. These doses are gradually increased over a more extended period, resulting in a decrease in sensitivity to allergens. Immunotherapy mainly focuses on improving cellular immunity, thereby encouraging the body to produce lesser antibodies, which contribute to allergic reactions. The treatment is continued for a longer period and at times, it might even take up to years of allergen shots before conclusive results are obtained. However, in most patients, significant results can be observed within a year of treatment.

Immunotherapy Injection

Forms of Immunotherapy

Advancements in the study of immunotherapy have paved the way for latest developments in this treatment. As a result, immunotherapy for seasonal allergies can now be given in various ways, including allergy shots, allergy tablets, and allergy drops. Allergy shots are the most effective form of immunotherapy that not only treat the existing allergy is but also prevent the development of any new allergies. They essentially act like vaccines and are required over a more extended period until the patient’s body develops resistance against allergens. Allergy shots also improve the way the immune cells respond to allergens. The effectiveness of allergy shots varies from person to person and depends upon:

  • the length of the treatment program,
  • the severity of the allergy, and
  • the doses of allergens given

Phases of Immunotherapy

The treatment is carried out in generally two phases:

  • Build-up phase: Immunotherapy shots are administered once or twice a week, and the allergen dose is increased gradually. In this phase, increasing resistance against allergens is observed.
  • Maintenance phase:  Allergy shots are given once every three to four weeks, depending upon the patient’s response during the build-up phase.

Immunotherapy Effectiveness

In a study conducted by Professor G. Walter Canonica, Professor of Medicine in the University of Genova and Professor Stephen R. Durham, Professor of Allergy and Respiratory Medicine in Imperial College School of Medicine (London), it was concluded that immunotherapy has long-term benefits in seasonal allergies and in some cases, it reduced the need for allergic medicines by 44%. The study also confirmed the long term benefit of this method for cat allergies. Another study by Hal Allergy group has shown a success rate of 80-90% in patients with seasonal pollen allergies, and a success rate of 90-100% in patients with bee or wasp venom allergies. The group also determined the general success rate at 70-85%. However, immunotherapy shots are not effective against food allergies and are therefore not used for such allergies. Immunotherapy is an effective treatment against several kinds of allergies, including:

  • Seasonal allergies such as hay fever, seasonal asthma, and pollens released from flowers.
  • Indoor allergies such as cockroaches, dust mites, and pets, including cats and dogs.
  • Insect stings, including wasps, bees, and hornets.

Failure to respond to immunotherapy shots may be due to several factors, including:

  • A low dose of allergen in the allergy vaccine,
  • Misidentification of allergens during the allergy evaluation,
  • Presence of high levels of allergens in the surrounding environment,
  • Exposure to other non-allergic triggers, such as tobacco smoke.
Immunotherapy Needle and Syringe


Immunotherapy for seasonal allergies is generally more beneficial for patients who:

  • have severe allergies which cannot be cured by usual medications,
  • suffer from life-threatening allergies such as asthma or anaphylaxis,
  • experience side effects on their standard medications.

Side Effects

Some people might experience side effects of allergen shots, including:

  • swelling and redness,
  • itchy skin,
  • nasal congestion, and
  • sneezing.

Other medical conditions, such as severe respiratory diseases or pregnancy, can increase the risk of adverse side effects. Therefore, it is advisable to always discuss your circumstances with your doctor before getting immunotherapy shots. In severe cases, a patient might develop anaphylaxis, leading to breathing difficulties and dizziness. In such cases, you should consult the doctor on an emergency basis to prevent any worsening condition. Most of these side effects develop within 30 minutes of administration of allergy shots. Therefore, it is always recommended to get allergen shots only by an approved doctor and stay under the doctor’s supervision for 30 minutes. Patients are advised not to inject the allergen shots on their own or without any supervision.

Immunotherapy Injection in Shoulder


It is recommended to avoid arduous exercise 2 hours before and after getting allergy shots. It is best to inform your doctor about any medications that you’re taking, including health or vitamin supplements. You should also undergo tests to determine the allergens as well as the intensity of allergy, be it a chronic allergy or a seasonal allergy.


In conclusion, immunotherapy has scientifically and medically proven benefits, especially against seasonal allergies. Immunotherapy has proven benefits including significant decrease in allergen sensitivity over an extended period. Moreover, allergen shots are a safe method for immunotherapy; however minor side effects may be noticed in some people.

Written by: Madiha Ather Hashmi (June 09, 2020)

Medically Reviewed By
Dr. Ahmed Abdelmajeed
Alexandria University Hospital

I have reviewed the articles on and I would like to say that I was very surprised.
Over years, I have seen many different articles in the field of allergy, but these articles were very interesting.
These articles were really unique, they could help many people around the world to know more about seasonal allergy, symptoms, prevention and when to seek medical advice.
These articles represent an addition in the field of Health Education not only for people with allergy but also for the whole population.

Looking for more treatment options? Find a full list of other seasonal allergy treatment options here.

Last Updated on July 5, 2023

Seasonal Allergies