Important questions to ask about starting allergy shots (immunotherapy)

Are you considering starting allergy shots (immunotherapy) to help your allergy symptoms? If you suffer with bad allergic rhinitis (hay fever) symptoms due to allergies to pollens, dust mites, moulds or animals, you may have heard about or had allergy shots recommended to you.

Allergy shots are a long term commitment and not for everyone. I’ve just started immunotherapy here in Australia for 8 different allergens: 6 types of pollen (grasses and trees) and two types of house dust mites. Here are some of the questions I had before my first appointment and you might have too if you are thinking about starting allergy shots as a treatment option.

The aim of sharing these questions is to help guide discussion with your doctor. Your treating allergist will explain the process to you and is of course the best person to answer any questions you might have. After all, they know about your own allergies and symptoms. And treatment can be different for different allergens, between different allergy practices and in different countries too.

What are allergy shots and how do they work?

Immunotherapy is not actually a “cure” for allergies. It is a type of treatment that helps desensitise you to certain allergens. By exposing your immune system to gradually increasing amounts of the allergy culprit, it can teach your immune system to tolerate or “get used to” the things that cause your allergies. This in turn can reduce your allergy symptoms. The aim is to “switch off” the allergic response. This is different to taking allergy medications like antihistamines or nasal sprays, which only treat or supress the symptoms of the allergic response.

“Allergy shots” or injections (also called “subcutaneous immunotherapy”) are one type of immunotherapy. There are other types of desensitisation treatment available. One of our children has had sublingual immunotherapy (using allergen drops under the tongue). Tablets are also available for some types of grass pollens and dust mites. (I was hoping I might be able to take a tablet for my grass pollen allergy, but as I have allergies to both grass and tree pollen it means that I need a different combination.) Each of these types of immunotherapy use the same approach to expose your immune system to allergens and build up tolerance over time. This post is only going to look at allergy immunotherapy injections.

When are allergy shots recommended as a treatment?

Doctors will frequently recommend immunotherapy if you have an allergy to dangerous stinging insects like bees or jack jumper (hopper) ants. This type of allergy can be life threatening and it may be difficult to avoid being stung.

For pollens, house dust mites, moulds and animals, other considerations might be important. Things to consider when deciding whether to have allergy shots include:

• if you suffer with severe symptoms;
• if your allergy trigger is hard to avoid;
• whether other treatments like allergy medications are working to control your symptoms;
• lifestyle factors (for example your work environment, or choosing to have a pet);
• if you have asthma.

Treating hay fever symptoms may also help prevent some people from developing new allergies or asthma¹.

How to decide which allergies to treat?

Your allergist will be able to make recommendations on which allergies to treat with immunotherapy. It’s not always a simple thing to work out, especially if you have multiple allergies.

Allergy testing

When you first see an allergist about hay fever or allergic rhinitis, or symptoms you experience around animals, you will no doubt have allergy testing. This could be an IgE blood test, and often skin prick testing. Some allergists do patch testing. You can read more about different types of allergy testing in our post about genuine allergy testing. I’ve also done a separate post about my experience with skin prick testing to identify my hay fever triggers – What is allergy testing for hay fever really like?

Your allergist will look at your allergy test results together with your clinical symptoms to work out what allergens to include in immunotherapy. It’s important to consider when you have allergy symptoms and your exposure in deciding what to treat. For example, house dust mite allergy symptoms can occur all year, but pollen allergies will depend on what types of plants are flowering at a particular time where you live. For me this includes spring grass pollens in my city. This is why it’s important to tell your allergist about your symptom history in as much detail as you can.

Other avoidance or treatment options

I am the third member of our family to have immunotherapy for house dust mites. My symptoms are hard to pin point, but I do wake up quite congested and with sinus issues. And that’s despite making every effort I can to reduce my exposure to dust mites. We have dust mite covers on all our beds, hot wash our bed linen, use vacuums with HEPA filters and more. (See How to get rid of dust mites: Practical allergy tips.) However my allergist recommended that with my test results and year round symptoms it was appropriate to try immunotherapy too.

I am also allergic to a lot of different pollens and have almost unbearable symptoms during the spring pollen season. This is despite using daily (or twice daily) antihistamines, a steroid nasal spray and mast cell inhibitor eye drops. It was an easy decision for me to try immunotherapy for these. Even a partial improvement in symptoms will make a big difference to my life.

Practical reasons

Guinea pigs are my other obvious allergy. I break out in hives when I touch our pet guinea pigs and sneeze near their cage (which could also be the hay). My allergist and I talked about whether allergy shots for guinea pigs would help. This is where other factors are relevant for me. If it is going to take more than 3 years to complete immunotherapy, it’s highly likely that we won’t still have guinea pigs as pets by that time. We’ve had our furry friends for a while now, and aren’t likely to get any more. I can also take practical steps to limit my exposure to some extent, which I talk about here: Guinea pig allergies: when cute cavies make you itch. Now, if I ran a guinea pig rescue, bred guinea pigs, or planned to have them in my life forever, I might have seriously considered immunotherapy for them as well.

Another family member is allergic to dogs, but we have chosen to try practical ways to minimise allergy symptoms rather than immunotherapy as the symptoms are relatively minor and easy to control.

Are allergy shots effective?

Allergy shots have been used for many years and have been shown to reduce symptoms of lots of different allergies. Measuring how much of a difference immunotherapy makes can be hard, because it is subjective. It relies on the person having the treatment to report an improvement in their symptoms.

According to ASCIA, after immunotherapy we should be able to expect:

• less frequent or less severe allergy symptoms (for example, less severe hay fever symptoms in spring after treatment for pollen allergies);
• less reliance on allergy medications like antihistamines and nasal sprays or more symptom relief from those medicines because they are more effective.¹

I am excited that my allergist is confident that allergy shots will improve my symptoms from what they are now. Whether that is 50% improvement, or more or less than that, it is hard to predict at the start. But I will happily take any improvement at all. It is very likely I won’t need as much allergy medication to control my symptoms.

Monitoring progress

Your allergist will talk to you about whether you are seeing any improvement in symptoms during the course of your treatment. It might take a year, or you might not notice improvement in pollen allergies until the next pollen season.

Some people might not have a very good response, which could be to a number of factors. It may be that you are allergic to something else that you aren’t receiving treatment for, there are very high levels of allergen in your environment, or perhaps a problem with the dosage of allergen. It might also be because you haven’t strictly adhered to the treatment program by missing doses. Your allergist will talk to you about your symptoms over the course of treatment, but if you have any concerns or queries you should always ask.

How long does immunotherapy take?

Immunotherapy treatment has two stages: a build-up phase and a maintenance phase. It’s exactly what it sounds like. During the build-up phase the amount of allergen in your injection is gradually increased. Once you reach the highest dose, your injections will have the same amount of allergen each time and be given less often.

How long the build up phase and maintenance phase take may depend on your allergist’s usual practice as well as how sensitive you are and how you react to the treatment. For me, the plan is 3 months of weekly injections during the build up phase and then monthly injections for maintenance for almost 3 years. The whole process normally takes 3 to 5 years.

When should I start allergy shots?

Your allergist will be able to tell you whether you can start straight away (often possible with year round allergies like house dust mites). For pollen allergies, it is normal to wait until after the pollen season to start treatment.

How much does immunotherapy cost?

It’s important to consider the costs of treatment before starting allergy shots. If you are not clear about this, make sure to ask questions so you know what you are committing to. The desensitisation process takes a number of years, so you should consider if you can afford the whole treatment course.

Allergy shots are not cheap. Factors that can affect the cost include the type of allergen serums used, the length of treatment (which affects how much is needed) and your allergy practice.

I am having treatment using two different allergen injections. These are not premixed serums from a manufacturer. Instead, my allergist is using aqueous solutions made up in the office to contain the personal mix of pollens that we want to treat. I am paying approximately $200 per vial, which may end up costing over $1500 for each of my two allergen combinations over the course of the treatment.

In Australia, the Pharmaceutical Benefits Scheme (PBS) does not cover the costs of immunotherapy serums for environmental allergies. You will get a Medicare rebate for part of the costs of your initial appointments and allergy testing. And the cost of attending an appointment to actually have the injections. However the cost of the allergen serums is not covered. If you have private health insurance, you might be able to claim some of this cost from your insurer. This is a question to ask your private health insurance provider.

(If you are having immunotherapy for stinging insects like bees or jack jumper ants, the PBS will cover this in Australia.)

In the US, immunotherapy may be covered by some insurers.

How often do I have to have immunotherapy injections?

As mentioned above, when you are in the build up phase of treatment you will normally have injections once a week. Weekly injections are for around 3 to 6 months. Once you reach the maintenance dose, injections will be less frequent. My allergist plans to do these monthly, but I have heard of some people having allergy shots every fortnight before moving to monthly injections.

What happens at the injection appointments?

First injection appointment

At my first allergy shot appointment, the allergy nurse giving the injections spent some time talking to me about the process. My allergist had already explained the risks and potential benefits of injections to me when I decided to go ahead with the treatment, but this was a chance to discuss potential side effects some more. Before starting allergy shots, it is normal to have to sign a consent form confirming that you understand the risks of the treatment. This is something I did at the first appointment.

The nurse explained where she would give the injections (one in each arm, towards the back of my upper arm). We talked about what symptoms I might experience and what treatment I might have if I had a reaction. This was also an opportunity to ask lots of practical questions about timing of injections. For the first appointment, the nurse also took my observations (including my heart rate and blood pressure) as a baseline in case I had a reaction.

After this, I was asked to check the two vials containing my allergy serums to make sure that they were the correct ones (labelled with my name). Then it was just stand up, relax the shoulders, and I had one injection in each arm. I was asked to take a seat in the waiting room and stay for 45 minutes, just in case I had an adverse reaction. After 45 minutes, my allergist came out to speak with me and had a look at the injection sites. Then I was free to go.

Subsequent appointments

From the second allergy shot appointment, things are a lot quicker. Straight in to the nurse for a quick chat about any reaction to the last injections. Then check the serum vials are labelled with my name, and a quick injection in each arm. You’ll still need to wait around the 30-45 minutes for observation, so bring something to do while you wait. Again, my allergist checks the injection sites and has a quick chat before I go.

Do allergy shots hurt?

Usually the person giving allergy shots (in my case an experienced specialist allergy nurse) has lots of experience in giving injections. I can tell you honestly that I didn’t even feel the injections go in. Just a quick wipe with a swab and a quick injection. Allergy shots are given with a small fine gauge needle. It’s not at all scary, even if you aren’t a fan of needles. And having injections towards the back of my arms means I couldn’t really even watch.

Fairly quickly after the injections I began to feel a bit itchy. Much like a mosquito bite really. The dust mite injection never really progressed from that feeling. The pollen injection did get a quite sore, hot and intensely itchy later in the day. That’s because I was one of the smaller group of people to have a fairly large local reaction. But within 2 days the reaction had disappeared completely and my arm felt fine.

What are the possible side effects of allergy shots?

Minor reactions are normal

Most people have fairly minor reactions to allergy shots. My allergist says nearly everyone gets an itchy lump at the injection site. This normally goes away in a few hours.

Less common reactions

Some people (yes, lucky me!) have a reasonably large local reaction to the injections. I have the dust mite injection in my right arm because I am right-handed and this injection doesn’t give me as much of a reaction. However the pollen injections so far have given me quite a large, painful lump at the injection site and a red itchy area about the size of the palm of my hand. It gradually gets worse over the course of about 6 to 8 hours, and then starts to get smaller. It takes about 2 days to stop being red and itchy.

My allergist has recommend that I continue to take an antihistamine on the day of my allergy injection to reduce the reactions that I get. I take antihistamine every morning anyway, so I often take a second dose the night after my injections when they are very itchy. At the moment the reaction is bearable, and doesn’t interfere with anything I need to do, so I’ll keep going at my current dose. If it ever becomes too uncomfortable to put up with, my allergist has said that we can change the speed at which we increase the dose. This just means the whole process will take a bit longer. For now antihistamine and an icepack is enough though. I can also take a paracetamol tablet if my arm is very sore.

Serious reactions are rare

Another member of my family actually had quite an unusual reaction to allergy shots and had to stop temporarily. The first 2 injections caused a sudden and severe increase in allergy and sinus symptoms and he had to stop treatment. Hopefully changing to a lower dose and more gradual increase to maintenance will help when starting again.

Serious side effects or allergic reactions (including anaphylaxis) are fortunately rare. This is something I was definitely concerned about, as my family has a history of serious reactions to all sorts of things. This is why it’s normal for your allergist to ask you to wait in the waiting room for 30 to 45 minutes for observation, just in case.

After one of my increased doses, I did experience a more serious reaction. After about half an hour I developed an irritation in my throat and a cough. This quickly progressed to a feeling of shortness of breath and wheezing. I alerted the staff and my allergist quickly came to review me. The allergy nurse gave me some ventolin to take through a spacer, which helped relieve my wheeze. I also took an additional dose of antihistamine. Because of this reaction, I had to stay longer for monitoring and my allergist has been keeping an eye on me at appointments ever since.

You will probably also be told to avoid doing strenuous exercise after your injection. You might need to have your injection at the end of the day if you have a very physical job.

Most importantly, if you do have an unusual reaction to your allergy shots, you should seek medical treatment straight away if it is severe. Otherwise, you should tell your doctor at your next appointment.

What happens if I miss a dose or need to change my appointment date?

For the first 3 months (or the length of time your dose is increased up the maintenance dose), injections will probably be weekly. I try to make my appointments on the same day each week, but there are times when this just isn’t possible due to other commitments. My allergy nurse has confirmed that it’s fine to have my injections on different days of the week if I need to. It’s not a good idea to miss a week altogether, as we may need to repeat instead of increase the dose and the build up phase will take longer.

Once in the maintenance phase, I will be having injections once a month. Again, it’s best to stick to the same time each month, but it doesn’t have to be to the exact day. Just as close as possible.

What about going away on holidays? (Although a lengthy trip away is not very likely for most of us at the moment with Covid-19). Our practice suggests that I time my appointments so that I have one injection before I go away and one as soon as I get back if it is due.

What if you are unwell? If you are feeling sick you should contact your allergist’s rooms and discuss whether you need to delay your appointment. (Not just because the injection might affect you differently when you are unwell. Your doctor won’t want you attending the office either!)

Do I have to have my allergy shots at the allergist’s rooms?

You should have your allergy shots where medical help is available in case you do have a reaction.

You might be able to have your ongoing injections at your local doctor’s office if it is more convenient for you. This is something you should ask your treating allergist. In my case, because I am having a mix of different pollens in an aqueous solution made up at my allergist’s office, there is a slightly higher risk of having an adverse reaction. So for this reason I have to go to the allergist’s every time.

Can I have allergy shots when pregnant?

It’s not recommended to start immunotherapy if you are pregnant. You should obviously disclose this to your allergist at your first appointment. What about if you become pregnant during your treatment? This is a question to ask your allergist. You may well be able to continue with the treatment if you want to (if you are in the maintenance phase).

Allergy shots and other medications or vaccines

Your doctor will have talked to you about other medications you are taking at your first appointment. If you have been prescribed any new medications during your immunotherapy treatment, you should let your doctor know at your next appointment. Some blood pressure or heart medicines might increase your risk of a reaction.

If you are having regular allergy shots and are scheduled to have a Covid-19 vaccination, you should ask your treating allergist about how this might affect the timing of your treatment. This is true for other vaccines too.

My allergist has a sign up in the office stating that patients should wait 2 days after an immunotherapy injection before having the Covid injection. And we should wait for 5 days after having the Covid injection to have our next immunotherapy injection. Make sure to check what your doctor recommends.

References and more information

I am only 2 weeks into my allergy shots, so I am sure I will think of more questions as I go along. Hopefully these will help you if you are considering starting allergy shots too.

For more information about allergen immunotherapy, your first place to ask should of course be your treating doctor. They know you and your allergies and can give you appropriate advice for your own circumstances.

If you’d like more general information about allergy shots, we recommend reading these helpful guides from peak allergy organisations that we’ve referred to:

• Australian Society of Clinical Immunology and Allergy, Allergen Immunotherapy and Allergen Immunotherapy FAQ
• American Academy of Allergy, Asthma and Immunology Allergy Shots (Immunotherapy)

¹ASCIA Allergen Immunotherapy Guide

*Disclaimer: Allergy Spot does not provide medical advice. You should always consult a suitably qualified medical practitioner in respect of your own medical conditions, symptoms or concerns. See our Website Terms for more details.