5 Side Effects Of Allergy Shots In Adults (My Experience)

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Over the course of my allergy shots (immunotherapy), I’ve experience 5 side effects. If you’re considering allergy shots it’s important to know the possible side effects.

Your reactions will likely be different than mine, but I hope my experience provides valuable insight!  After all, the last thing you want is to begin receiving allergy shots and experience reactions or side effect that were unexpected.

Choosing to go through with allergy shots is a long-term health decision that can result in significant improvements to your quality of life. They do, however, require patience and a significant amount of time.

If you’re really struggling with your allergies – more than just a few weeks of the year – allergy shots can bring relief.

Below, I’ll share my experience with side effects from the beginning until now (9 years later) and I’ll share my thoughts on whether allergy shots are effective. I hope you find relief just as I have.

My Experience With Allergy Shots

In my early 30’s I was struggling with my health. My allergies didn’t just appear out of nowhere, rather, my allergies had slowly crept up on me and began to affect my every-day-life.

I felt unhealthy, had allergic shiners (dark marks under my eyes), itchy skin, watery eyes, and always had a persistent stuffy nose. Worst of all I constantly felt fatigue.

I was in graduate school, busy with studying and an internship. At first I ignored the allergy symptoms because I had always experienced them.

As my health was snowballing downward (not an exaggeration) I stopped going to my internship. I continued to study but slept 12 hours a day. In class I would struggle to keep my eyes open.

I had no idea what was happening. Was this normal?

Eventually, I wound up at an allergist. He asked me a few questions and chose to tested for a few allergens. I tested positive for most things and began allergy drops. After a year I didn’t find much relief.

At this point I knew allergies were causing me to feel ill, so I made an appointment with another allergist.  This time I was tested for over 100 things (environmental not food).

Again, most of my results came back positive.

I’ve been working with my allergist for 9 years and I’ve learned how allergy shots work (read my personal review of allergy shots here). I’ve experienced a few side effects and I’ll share them with you below.

Types of Allergy Shots

It’s important to note that allergy shots are currently used for environmental allergens, not for food. You can be tested for environmental and food allergies, but the best way to manage food allergies is avoidance.

Environmental allergens (or aeroallergens) are outlined below:


  • Pollens (grasses, weeds, trees)
  • Dust Mites
  • Animals/Pets
  • Molds
  • Yeasts
  • Stings (bees etc.)

The test is relatively quick and only takes less than 30 minutes.  It’s also painless, with no injections (you can read more about my testing process here). Once you’ve been tested and examined you doctor will outline the options available.

The most common option is allergy shots or SCIT immunotherapy.  It’s a process that takes time to work (multiple years). I’ll outline the standard process as well as “rush and cluster” below.

Standard Allergy Immunotherapy

Most of my time with allergy immunotherapy has been the “standard” process. There are 2 parts to standard allergy immunotherapy.

  • Build up phase

The build-up phase is a slow process of weekly or twice weekly shots. The shots are given in the back of the arm or the thigh.

The first shot will be extremely weak, and if you don’t experience a major reaction to the shot the next dose will increase slightly. The shots contain the actual things you’re allergic to, so it’s important to go slow and minimize a bad reaction.

It took me 1 year to build up to a strong dose. You might be thinking “that’s too long”, but if your allergies were as bad as mine it’s worth the wait. Slow and steady your health will likely improve.

  • Maintenance phase

The second phase of the allergy shots is the maintenance phase. As the name suggests, you will maintain the strength of shot for a long period of time.

One of the good things about the maintenance phase is the shots are spread out further, sometimes weekly, biweekly, or even monthly depending on your improvement.

During the maintenance phase your doctor might retest you to find stubborn allergens and then readjust the dose. My dose has recently been readjusted so I am taking my shots closer together for added improvement.

Rush Immunotherapy

As the name suggests, rush immunotherapy is meant to speed up the shot process. Not all allergists offer “rush immunotherapy” but if they do I recommend you consider it.

One of the main reasons people don’t experience relief with allergy shots is because they miss shots or can’t commit to the schedule.

Rush immunotherapy consists of multiple shots spread out over a single day (or few days). The aim for rush immunotherapy is to reach maintenance dose quickly, where the majority of benefits begin to occur.

Rush immunotherapy works great for people who:

  • Want faster relief
  • Are willing to experience multiple shots quickly (tough guys and gals)
  • Have a busy schedule and can’t receive shots every week for a year
  • Are only mildly allergic to a few things

Rush immunotherapy has a higher risk of reactions.

Cluster Immunotherapy

Cluster immunotherapy is a hybrid of rush and standard allergy shots. During your shot schedule, you might receive 2-3 shots each visit to speed up the process.

Remember the goal is reaching maintenance dose and once you reach it you’ll likely feel more relief.

Cluster immunotherapy also has a higher risk of reactions.

Allergy Shots Side Effects for Adults

Allergy shot side effects or reactions are usually minimal and easy to manage. Because you’re being injected with allergens sometimes your body can overreact.

For this reason it’s important to always carry an Epi-Pen with you to the doctor, in your car, to work/school. I’ll explain the side effects and reactions I’ve experienced during my 5 years of allergy shots.

  • Small bump

Immediately after my shot I’ll usually have a small bump (smaller than marble). The bump isn’t painful or irritated, rather it’s a bump because of the fluid.

10-60 minutes after the shot the bump goes away. This didn’t happen every time I received a shot but I learned that it wasn’t a serious issue.

  • Light redness

An hour or so after the shot I usually experience light redness around the shot location (size of silver dollar).

When I first began shots I didn’t have skin reactions. Only when I became closer to my maintenance dose did I begin to see redness. I actually appreciate seeing the redness because I know my body is still reacting and there might be room for improvement.

The redness isn’t painful, just something I can see. It remains the day after the shot but dissipates the 2nd day.

  • Light itchiness

Occasionally, the shot location will itch a few hours after receiving the shot. This usually goes away within a day.

Sometimes I wake up after sleeping to find scratch marks on my leg. I have eczema so some of my allergies make my scratching worse.

  • Worsening of allergy symptoms for 2 days after shot (more the 2nd day)

After my shots I almost always experience a slight worsening in allergy symptoms for 2 days after the shot.

In my opinion this should be expected, right? You’re being injected with allergens and your body is reacting. For 2 days after the shot I usually take an extra anti-histamine.

My eczema always gets a little red (different parts of my body) and improves a few days after shots.

  • Fatigue for 2 days after shot

Fatigue was one of my main allergy symptoms so it’s not a surprise that I’m easily worn out after a shot. I think my immune system goes into overdrive when I receive the shot and makes me tired.

The fatigue is manageable but I’ve learned to not schedule my shot around important work events, presentations, or meetings.

I asked my allergists about this side effect and they didn’t say it was common, however, it’s important to understand that people experience different allergy symptoms and reactions to allergy shots.

Once I reached maintenance dose, my fatigue became less problematic. Needless to say, I have much more energy now!

Reactions To Allergy Shots Pictures (My Pictures)

I’ve included a few of my photos after allergy shots. The first allergy shot picture is the same day and is about 5 hours after the shot.

I believe this is normal and nothing to worry about. Conversely, if there was no reaction at all I’d think the shot was too weak.

The second photo (below) is the 2nd day after getting my shot. Notice the redness has significantly decreased.  By the 3rd day there is no mark.

side effects allergy shots

Can Allergy Shots Make You Sick

Everyone tolerates allergy shots differently. In fact, some people might not tolerate them at all.

I’ve never been sick from allergy shots, but I have noticed that if I have a cold or the flu and I get an allergy shot my cold or flu will worsen significantly.

I’m not a doctor so I would never answer this question definitively but think about the situation. With allergy shots you are being injected with things your body regards as harmful.

Frequent shots eventually teach your immune system to settle down and stop reacting so strongly.

The tips that I’ve used with my allergist:

  • Reschedule if you’re under stress at work
  • Reschedule if you’re ill from a cold or flu
  • Understand that the shots will exhaust your immune system for a day or two after the shot (however I’ve also been told I should feel relief immediately after a shot?)
  • Communicate to your allergist if you feel the shots are too strong (I had to do this and when we reduced the shot amount I felt much better)
  • Communicate to your allergist your reactions
  • Keep a journal – it’s useful to look back on and understand if a reaction is normal or out of the ordinary.

Allergy Shots Effectiveness – My Opinion

Are allergy shots effective? A few years ago, prior to starting allergy shots, I was in a horrible place.

I couldn’t make it to work, I stopped socializing, and I stopped exercising. I became obsessive about controlling my environment and reducing any stress.

I didn’t know what was causing me to feel bad and I didn’t know what to do.

Thankfully I was allergy tested.

But that didn’t solve the problem. The first allergist I visited didn’t help me.

He tested me for a couple things and gave me allergy drops – there was very little communication or explanation on his part. After that experience, if you were to ask if allergy immunotherapy is effective I would have said “no”.

Thankfully I was retested for allergies by a reputable allergist.

I received the full spectrum of tests and the process was explained to me. We decided on a way to move forward. I strongly believe that allergy shots are effective.

Over the past few years I’ve reduced my allergy symptoms by about 80%. I can breathe through my nose (something I could never do before) and my eyes are less itchy.

My fatigue is gone. I only need 7 hours of sleep a night and I wake up energized and ready to go. I’ve also been able to hold a job.

I suffered from allergies year-round, not just seasonally. I was desperate to find a solution and I’ve followed the schedule outlined by my doctor.

I’ve also been retested a few times to make sure the allergy shots are working.  Guess what? I no longer react to many of the allergens I first reacted to.

If you’re tired of suffering, consider SCIT immunotherapy. Allergy shots are effective and they can help you, but take time to find a reputable allergist and commit to the schedule.

Allergy shots aren’t fun, but they work.


In this article we discussed the side effects of allergy shots in adults. I shared my experience as an adult with allergies including the challenges and success using allergy immunotherapy.

It’s important to note that allergy shots aren’t given for foods, rather they are for environmental allergens, also called aeroallergens.

Environmental allergens are made up of pollen from grass, weeds, and trees, dust mites (indoor), mold, pet/animals, and yeasts. Allergy shots are also used for insect stings like bees.

I experienced year-round symptoms from environmental allergies and I’m allergic to almost 100 things.

The shots have helped me reduce symptoms of fatigue, eczema, rhinitis, conjunctivitis, and irritability but because the shots contain the same things I’m allergic to, they do have some side effects, or more appropriately “reactions”.

The side effects or reactions I’ve experienced are a small bump at the injection site, redness, itchiness, slight worsening of allergy symptoms (eczema), and fatigue. After 2 days I usually bounce back and feel energized.

If you’re considering allergy shots, think about the time commitment. Can you commit to multiple years? If your allergy symptoms are as bad as mine, the answer will be clear.

Also consider the types of allergy shots: standard, rush, or cluster. There are various benefits of each option.

I’ve been on allergy shots for 6 years with tremendous benefits (80%) and very little side effects.  I’ve been retested a few times during my shots to see my progress and my allergy shot dose has been adjusted (I believe this is very important).

Because the substance in the shots isn’t synthetic, there won’t be chemical side effects that you need to worry about.

If this sounds like an option for you I encourage you to search for a reputable allergist and be tested for allergies. Once you determine what is bothering you, your doctor can recommend solutions to improve your health.

34 thoughts on “5 Side Effects Of Allergy Shots In Adults (My Experience)”

  1. I like your blog a lot. It is very helpful for fellow allergy sufferers like me. I also recently started allergy shots about 7 months ago. Its a slow process like you mention. I alsO tested positive for many allergens. I am still 4 months (2 Vials) from reaching MAINTENANCE IF EVERYTHING GOES WELL. i have had some improvements but setbacks too. I still have lots of nasal congestion AND RUNNY NOSE. Do you think this will decrease over time? When did you see most improvements in your cASE. Thanks

  2. Thanks for the comment Venkat. It’s a slow process but if you’re working with a good allergist you should get relief. I also had a chronically congested nose. I remember being able to breathe through my nose clearly after about 1-1.5 years on the allergy shots (took me one year to reach maintenance dose). In my experience once you reach maintenance the real improvements will begin. Be patient and trust the process. Thanks for reading the blog!

  3. been on allergy shots over 25 years at least 5 shots a week allergic to bees wasps hornets ,dust , rag weed, you name dogs,. this week to see the DR before they would give me any more allergy shots. Well it is to COSTLY for him to continue to give me the shot for the bee shot–well go figure the Dr he recommended is not on our insurance plan . I am from Ohio.

  4. I have all the symptoms and live in central Fla. and allergic highly allergic to dust mites,etc..In reading this article I did not realize that one of the symptoms would make you really tired, but I have been told I’m showing a slight improvement after three months. My question how long do I have to continue taking the medication of two shots a week?

  5. Hi Vince, it’s based on your allergist’s recommendation. It could be just once a week. Usually, the immunotherapy is more frequent (once or twice a week) until you reach maintenance dose (1-1.5 years). Double check with your doctor.

  6. Thanks for writing this! Everything i researched and was told about allergy shots is that usually there is very little reaction but this isn’t true! My allergies sound like yours were – fatigue is my primary symptom. I am doing cluster and had a reaction several hours after my last cluster session that put me in the ER due to swollen face/eyes and hives, red face, and hives. The doctor diluted my solution based on that experience – I am still in the build up phase but at the point where i do one shot a week. I had a shot yesterday and feel exhausted today. Feels so good to have some confirmation that this tiredness is likely being caused by the shots! it was years before i figured out that allergies were the cause of my fatigue because i don’t really get the “regular” symptoms. Hopefully this effort is worth it – glad to hear that you have been helped!

  7. Strange isn’t it. When I first started I’d be exhausted for two days after the shot. I had heard that I should feel better after the shot (dunno). I’m just sharing how I felt and it seems like other people have experienced the same thing. Maybe it was because I didn’t sleep well when I took the shot (not directly related??). Keep going with the shots. I also had setbacks but I’m glad I was working with a good allergist and he continued to adjust my dose to get it right! I’m feeling pretty good these days (a few years later).

  8. Sounds like a tough situation, sorry to hear it’s been that long. I’ve been on the shots about 6 years now and I feel a lot better but I imagine I’ll be taking them for the next 5 years too. You’re right, it can be super expensive without good insurance. I’ve paid a lot out of pocket and finally have good insurance. Thanks for the comment.

  9. You’re the first person that mentioned ANYTHING about fatigue! I’ve been feeling so tired lately (I’m towards the end of my build up phase) and when I mention it to the nurse, they tell me it’s because alleviate and this time of year. So I started wondering if there’s something else that’s causing my fatigue, but now I’m positive it’s from the shots! I know it’s worth it in the long run. It’s just one of those things that get worse before they get better.

  10. How do you know the fatigue is not from taking the antihistamines? I switched to allegra and feel no fatigue. I am considering getting shots for dust mite and dog allergies. My quality of life is good, and I’m not even sure whether the severity of my symptoms warrants the commitment. As you said, sometimes you just get used to the way things are…..runny nose, itchy ears, inflamed nasal passages. How to decide?

  11. Hi, thanks for the comment. I only take non-drowsy Allegra and I usually get an energy boost when I take it. Fatigue is def not from anti-histamines (for me) but could be the problem for other people. Talking with your allergist about the pros and cons of allergy shots is the best option. I was having trouble living a “normal” life so allergy shots were something I felt necessary.

  12. Thanks for the insight!! Have only had 4 shots at this stage and am finding that for me I feel really crappy for 3-4 days after each shot. A massive reason for me doing this was due to severe sinus issues that I felt had worsened with severe allergies. (I’ve had 7 sinus operations…) I am still depending on strong pain meds on my bad days, but since starting on injections I think I can finally see light at the end of the tunnel!! I can have 2-3days of no pain – something I haven’t experienced for years 😊

  13. I’m not sure what type of build up phase I am on. I started at 0.1 ml and am working up to 1.0 ml where 1.0 will be my maintenance dose. I move up every week by 0.1 ml, so I should reach maintenance phase in about a month or so as I just had my 0.4 ml injection 2 days ago. I do feel really tired for a few days after the shot, so I am glad that I found this website. It sort of validates my suspicion. I do wonder though if this is a form of rush immunotherapy? Does anyone know what the typical frequency for dosage increase is?

  14. Glad it helps. I’m not sure the typical frequency, I have a feeling it’s different based on the allergist’s own methods. I tried to figure mine out based on the ml, but it was confusion and my allergist lowers it when I get a fresh vial (because they are more potent). The two allergists I’ve seen were very different. As long as you can handle the shots, I think rush immunotherapy is a great choice!

  15. Thank you again for this site. I tested positive for moderate to severe allergies and started my allergy shots today. I’m hoping these shots will help! I also have a chronically congested nose and other symptoms. Thanks again for the information!

  16. It takes a while, be patient. Allergy shots were one of the best decisions I’ve made. My nose was also chronically congested…no longer and I sleep much better. Hope you experience relief.

  17. Thank you for this post and to the others that have commented, I’m just beginning my journey so it’s really helping to see others reactions to the therapy. My allergist is 5 hours away but she’s amazing so I’m just getting my injections at the local drs office so I feel more like I have to monitor and discover things for myself along the way. Thankfully my allergist prescribed me an Epi-pen just in case (I’ve never had an anaphylactic reaction but better safe than sorry) so I feel a little more secure at home. Well time to nap off injection day, I’m pooped out lol!

  18. So glad I found this! Have been searching and found nothing on this until today. I am 10 months into my shots, at maintenance on 1 group & still building on the other. After my shots I get gritty eyes & stuffy nose but am also EXHAUSTED for the next 4-5 days, sleeping heavier than ever in my life. Start to feel better and then shot time again and it starts all over. I felt it was the immunotherapy causing this but wasn’t sure. Thanks to all of you for confirming my suspicions!

  19. Crazy I am the same way!! Just started shots about 2 months ago… I was so allergic to the trees and grass after moving to SC. So bad it caused digestive issues for me causing me to lose 45lbs!! We just increased my dose today and almost instantly I felt like
    Junk. Dry itchy eyes, heart palpitations… allergies are no fun at alll

  20. I’m so glad to read that other people have had fatigue, too!

    I got VERY TIRED during the 30 minutes after my shots yesterday, and asked the nurse about it. I told her I came in feeling normally, but I felt like I *had* to sleep right then — to the point that I was going to have my husband pick up my daughter from school (usually I pick her up immediately after my allergy shots). She looked at my arms and said they looked fine (a bit red, as usual), and asked me if I was having any trouble breathing. I said no.

    She said that it’s not a common reaction, but that she has one patient who has to go home and sleep immediately after her shot. She said that for some people, the antihistamines we take in the morning don’t really kick in until they hit a trigger like our allergy shot — and then they hit it us all at once, which could make some people sleepy.

    My allergy medicine doesn’t usually make me sleepy (Zyrtec), but maybe this is a factor?

    Anyway, it’s almost 24 hours since I got shots and I still feel exhausted. My arms are very itchy today, also, and still swollen.

  21. Yes, it’s strange isn’t it? During the build up stage I felt most tired the 2nd day, exhausted. Now that I’m at maintenance dose I rarely experience the fatigue like I used to. I think my immune system was working so hard to fight off the allergens and it wore me out. The good thing, it’s a sign that your allergist is addressing the correct allergens! Thanks for the comment and best wishes in your recovery.

  22. Increase the dose and experience symptoms…that means the shots are addressing your allergens. Stick with it and after a few months on maintenance dose you’ll be feeling better (at least that’s been my experience).

  23. I experienced similar reactions. Stick with it through maintenance! It can be uncomfortable but the long term results of immunotherapy are usually quite good. I’m feeling better than ever!

  24. Hang in there with allergy shots. It takes a while (sometimes a year or two to notice a difference), but I can’t recommend them enough. My allergist was 2 hours away, but the commute was worth it because he was really good! Best wishes and thanks for the comment!

  25. I have been getting allergy shots for about 4 weeks. I also have experienced fatigue. In addition to that the inside of my mouth is very sensitive and I have bumps and slight swelling. I asked about this the last time I received a shot, they did not seem concerned and said they had never heard of that reaction.? The tissue inside my mouth feels kind of raw.

  26. Yep, even my questions to my allergist were met with “don’t worry about it”. I think we all feel slightly different symptoms. As long as it’s not life threatening, try to push through. A few months on the maintenance dose and all of those symptoms slowly subsided. I experience very little fatigue now! :)

  27. I used to get that symptom more at the start but it has pretty much subsided. Being a woman I find that it can sometimes flare up around “that time” and my shots. I honestly feel like this whole thing is either I’m fine or for some random reason (no change in diet or setting) and I’ll have a bad reaction day which will leave me tired out the next day. Oddly enough I find if this does happen it’s usually mid-week of my shots now…maybe I need to slow down?

  28. I have been on shots about a year now. They are helping. But the last two I seem to have weird reactions. Two weeks ago, I felt really hot and then lightheaded, had to sit in the office awhile before leaving. Today had my shot, sat the required 39 minutes. But since returning home, I am having chills, and a strong sense of something is not quite right. I cannot seem to get comfortable. I keep moving from place to place. Putting a sweater on and off.

  29. I’ve been taking allergy shots since 2016 or about 3 years now. Absent once instance, when I had a mild allergy day (runny nose, runny eyes), it lasted less than 24 hours. In the grand scheme of things this was just a road bump but it seemed like my body got control of a full out allergy rush. I had gone to see an allergist sometime in 2014 and based on some testing he advised me that I didn’t have any allergies, he stated it was a condition caused by changes in atmospheric conditions. For years, I thought I didn’t have any issues. Then, in 2016 I had the full scale allergy attack. It’s so bad that I’m just not functional, can hardly drive or keep my eyes open. I’m miserable. In that instance and during the attack, I went to see an ENT. We started testing (deeper type) injections and she found the allergens. So for nearly 4 years, I’ve been symptom free. Normally, I would get these 2-3 times a year and they would last anywhere between 4-7 days of sheer misery. So, my ENT is changing offices and I hadn’t gotten my new mixture so I just kept upping the dosage – not a good idea. Within a few hours after my last dose of .60 (12/22/20190 (I’ve never taken more than .50 before I restarting a new mixture/vial), I had a pretty good reaction. Fortunately, I had some medications, which has made the episode more tolerable but I find it difficult to get work done. And, the worst was the chronic fatigue and body soreness. Anyway, I’m to see the doc soon to learn more about that happened or got myself into.

  30. I just had my weekly allergy shot and am VERY sleepy now. It could be the diphenhydramine you mention. I have to take something to make sure I don’t over-react to the shots though.

  31. Same here. I guilt back 3 hours ago & I’m just waking up from a 1.5hr nap… still feeling exhausted & fuzzy. I sometimes want to give up. The 3 or 4 last times have been like this… I feel so fatigued & brain fog

  32. Glad I found this article. I have been doing sublingual immunotherapy for allergies for about a month. I am so fatigued all the time. With drops you do them every other day and I feel exhausted day after day. I am sure it is thr drops but going to call the allergist and mention it. I hope it eventually subsides.

  33. Great write up. My journey began while trying to find relief of a stuffed up nose especially at night. It significantly affected my sleep. I had nose surgery which helped overall but didnt alleviate all of the stuffiness. I chose the rush option and had my last build up shot today. I found your article searching for drowsiness, because for about 30 minutes I feel noticeably tired after my shot and hadnt seen that as a possible symptom before. I’m hoping my stuffy nose continues to improve, although it is better than before I started taking shots.

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