HomeAnswersAllergy Specialistanti-allergy medicationsI have an allergic reaction after taking allergy shots.

How long will the effect of allergy shots last?


The following is an actual conversation between an iCliniq user and a doctor that has been reviewed and published as a Premium Q&A.

Medically reviewed by

iCliniq medical review team

Published At August 12, 2022
Reviewed AtOctober 13, 2023

Patient's Query

Hi doctor,

I have tried allergy shots twice over the last two years and had to quit due to adverse effects both times. The first time in six months of shots, it had no noticeable impact. The second time I quit it in eight months. The second time I reached the maintenance dose for five injections. My allergies have almost completely cleared up in just one month since hitting the maintenance dose. I have quit shots now, and I wonder how likely my allergies are to relapse given the duration of the shots I got. How long will the effect of shots last? Is it likely the allergy will return with the same intensity as before? Kindly suggest.


Welcome to icliniq.com.

I have gone through your history and details of the allergy shots. From the allergen report (attachment removed to protect the patient's identity) it is very clear that you have a significant allergy to trees, grass, pollens, and dust mites. First of all, I would like to give some details about the allergy shots and then will answer your query. Allergy shots, also called immunotherap help your body get used to allergens (the things that trigger an allergic reaction). They are not a cure, but over a period of time, your symptoms will get better and you may not have symptoms as often. Immunotherapy is advised if you have symptoms for more than three months a year and medicines do not give you enough relief. The serum is prepared in enough dilutions and scheduled in increasing concentration at least over three to five years usually. In your query, you mentioned, that you took it only for eight months including the first failed attempt. So it is very likely that initially, allergy symptoms may have disappeared but because of inadequate duration, there is a relapse of symptoms again. Also, you need to see if any other medicines or herbal supplements are having adverse reactions to allergy serum.

So I suggest you talk to your allergist about the appropriate duration of therapy in appropriate dilutions as per your allergy reports. The relapse symptoms may be similar to earlier but sometimes they may be worse and difficult to control.

Usually taking antihistamines tablets like Levocetirizine (Levocetirizine dihydrochloride), Claritin (Loratadine), and Montelukast (Montelukast Sodium) can help to alleviate allergic reactions like itchy eyes, shortness of breath or sore throat. If you get stomach upset, antacid tablets and liquid are advisable for prompt relief. Minor allergic reactions like redness, swelling, and pain at the injection site are very common initially and there is nothing to worry about it. To summarize, I would suggest you to

  1. Talk to your allergist about prolonging the duration of therapy and try little higher dilutions with appropriate care for optimal benefits.
  2. Also, you can try allergy shots from a different brand company as sometimes under dilutions or the wrong combination of different allergens does not work appropriately.
  3. Hence, it is of utmost importance to discuss all these issues with the treating allergist.
  4. I hope this answers your query.

    Thank you.

The Probable causes

Trees, pollens weeds, and dust mites allergy.

Differential diagnosis

Allergen immunotherapy.

Treatment plan

As discussed in the answer.

Patient's Query

Hello doctor,

Thank you for the response. I will discuss what you have said with my allergist. So given that I had six months of shots on the first attempt and then eight months with five maintenance injections on the second attempt, are my allergies likely to relapse because of insufficient duration? Kindly suggest.


Welcome back to icliniq.com.

Regarding your query, yes, it is very likely that the relapse of the same allergy symptoms could be because of the inadequate and suboptimal duration of the allergy shots. Usually, it is advisable to continue therapy at least for two to three years to build an excellent immunological response. Then only the recurrence of allergic reactions is reduced. Due to suboptimal duration, initially, you will have much improvement in the symptoms. Still, the waning of immunity without reduced exposure leads to similar symptoms or more severe than earlier. Hence, appropriate dilutions and duration of allergy shots determine the final response to the immunotherapy.

I hope this clears your remaining doubts.

Thank you.

Treatment plan

As discussed earlier.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Amol Kumar Wasudeorao Diwan
Dr. Amol Kumar Wasudeorao Diwan

Allergy Specialist

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