Can allergies change over time?

August 2022   Linda Armstrong  |  ✓  Medically reviewed by: Fabio Iachetti, MD; Eva Södergren, PhD, MSc

Fabio Iachetti is a licensed physician with more than 15 years of diverse experience in several disease areas such as allergy, CV, pain, GI, rheumatology, urology, and diabetology. He is a Senior Medical Manager for Allergy in ImmunoDiagnostics Global Medical Affairs at Thermo Fisher Scientific. A nutritionist by training, Eva Södergren now works as a Senior Scientific Advisor for Allergy on the Medical and Scientific Affairs team for Thermo Fisher Scientific’s ImmunoDiagnostics division.

The short answer is “yes.” Allergies are dynamic, not static. Just as the human body doesn’t remain constant from birth to death, neither do allergies. They can change due to a host of factors, including some you’re likely able to control and others that are out of your hands. In fact, when it comes to allergies, the old adage applies: Change is the only constant.

These allergy fluctuations, then, can be both positive and kind of gnarly. While you may develop allergies over time and existing allergies may increase in severity (ugh!), allergy symptoms can also decrease and/or disappear entirely (squee!).

The following info will help you better understand the dynamic nature of allergies. Along with insights about the potential causes of and factors related to allergies, you’ll find stats about outgrowing allergies, info about the importance of allergy testing (and retesting), and more. 

What are allergies?  

To understand how and why allergies change over time, it’s important to first comprehend what allergies are and what factors might impact them.

In simple terms, an allergy occurs when your immune system overreacts to a food or foreign substance (e.g., eggs, dust mites, cat dander, ragweed pollen, etc.) that wouldn’t normally be harmful to your body. Ultimately, the body releases chemicals, such as histamine, which cause symptoms (e.g., runny nose, scratchy throat, hives, anaphylaxis, and more).

What factors might cause allergies?

Science isn’t 100-percent certain about what causes allergies and why some people develop them and others don’t. But many sources can agree on three potential factors that play a role in allergies.

  • Immune System. Since allergies are an immune system response, it stands to reason that the condition of the immune system may impact the development and/or severity of allergies.
  • Genetics. Whether we develop allergies is likely due in part to our genetic makeup.1 The term “atopy” refers to the genetic tendency to develop allergic diseases such as allergic rhinitis, asthma, and atopic dermatitis.2
  • Exposure. To develop an allergy, you need to be exposed to an allergen. Logically, then, our environments and the allergens within them impact allergy development. However, science isn’t sure whether exposure is helpful or harmful. Repeated exposure might help some people build allergy-busting antibodies (and thus tolerance) to the allergen. However, for other people, steering clear of the allergen altogether might be better, as it would prevent them from developing an allergy in the first place.1

Clearly, the cause of allergies isn’t black and white. But exposure, immune systems, and genetics are likely involved.3

How might allergies change over time?  

OK, so allergies are dynamic as opposed to static. But what does that really mean? Certainly, each person’s allergy journey is unique, but how might allergies change over time? 

  • Allergies may develop and/or worsen in adulthood. According to an article published in the Journal of the American Medical Association, adult-onset food allergies are common, severe, and an important and emerging health problem. In fact, for nearly half of food-allergic adults, at least one of their allergies began in adulthood.A person might also develop a food allergy to something he or she has eaten for years without any problems.5 Additionally, an article in New Scientist magazine indicates there are even reports of middle-aged people suddenly becoming sensitized to pollen, likely after previously contacting some form of it without issues.6
  • Mild symptoms may become severe and vice versa. Allergy symptoms can fluctuate throughout your lifetime, both increasing and/or decreasing in severity. Plus, a food that triggered mild symptoms on one occasion may cause severe symptoms such as anaphylaxis another time.5
  • Allergies might disappear. Allergies can also resolve themselves. In fact, almost 20 percent of children outgrow their allergies by the time they’re school aged.7 Sometimes, though, allergies disappear only to return years later.8

Can we outgrow food allergies? 

Some allergies may be here to stay, but some food allergies may be temporary. Here are some stats showing which allergies kids are likely to outgrow and which ones are likely permanent.   

  • Milk, Soy, Eggs, and Wheat. A whopping 80 to 95 percent of children outgrow their milk, soy, egg, and/or wheat allergies by age 5.9
  • Milk (Infants). By the time they’re 12 months old, roughly 50 percent of infants with a milk allergy develop tolerance for milk.9
  • Sesame. Sesame allergy seems to appear early in life, and according to one study persists for 80 percent of children. If they were to outgrow sesame allergy, they typically do so by approximately 6 years of age.10
  • Peanuts, Tree Nuts, Fish, and Shellfish. In 80 to 90 percent of cases, allergies to peanuts, tree nuts (e.g., almonds, Brazil nuts, cashews, hazelnuts, pecans, pistachios, walnuts, etc.), fish, and shellfish are lifelong.9

Why do allergies change?

Why do you have allergies now when you didn’t before? Why have your allergy symptoms suddenly disappeared?

If we know that the immune system and exposure play a role in allergies, altering these things may lead to allergy fluctuations. Here are a few factors that may impact allergies over time. 

Immune System Variations

Your immune system is constantly fluctuating as it adapts to invaders, repels familiar foes, develops and loses tolerances, etc.11 And myriad elements can both damage and strengthen your immune system. For example, digestive tract changes may impact immune responses and lead to the development of food allergies.12

Aging is another culprit. In some instances, children can outgrow allergies. And in others, elderly people may actually develop them as a result of an aging immune system.12

According to an article in Aging and Disease, a peer-reviewed online journal, the immune system is altered significantly during aging, as some functions become more active while others decline. These changes may lead to increased susceptibility to infections and autoimmune diseases; plus, they may put elderly people at a higher risk of developing food allergies.12 In fact, allergic diseases can often persist into old age and can occasionally appear in the elderly.13

Stress, Obesity, and Hormones

Some may argue that stress can impact your immune system and thus affect allergies in a nondirect way. Others also suggest that while stress isn’t actually the cause of allergies, it can certainly make allergies worse, as stress releases hormones and histamine, among other things, that can enhance allergy symptoms.12

Similarly, weight gain and obesity may affect the immune system, possibly leading to less well-controlled allergy and asthma symptoms. Plus, the immune system may fluctuate in relation to hormonal shifts. At least anecdotally, pregnancy, menopause, and puberty have been linked to allergy changes.14

Environmental Changes

Since exposure plays a role in allergies, experiencing different environments may lead to allergy changes. For example, thanks to foreign travel, some people may encounter new allergens and develop new allergy symptoms.6 Similarly, a common reason people acquire new seasonal allergies is moving from one geographic region to another. That is, each location has a unique mix of vegetation, causing some people’s allergies to increase and others to lessen.15

Keep in mind, however, it sometimes takes time to develop allergy symptoms. With pollen, for example, you may need to experience a few pollen seasons to become fully sensitized and develop symptoms. As such, pollen allergies usually show up in children after age 3. Conversely, symptoms of indoor allergens (e.g., mold, dust mites, etc.) may be triggered as early as 1 year of age, likely because the child is exposed to these daily as opposed to seasonally.16

Why is it important to identify allergies?

To lessen allergy symptoms, you likely need to know what’s causing them. After all, you can’t reduce allergen exposure if you don’t know what to avoid.

Particularly given the fact that allergy severity can unexpectedly ramp up from mild symptoms to life-threatening reactions such as anaphylaxis, understanding triggers is paramount. And since allergies can change at any time, you can’t rely on information obtained from allergy tests you had five, 10, or 20 years ago.

A simple test called a specific IgE blood test along with your symptom history and physical exam may help your healthcare provider diagnose your allergies. But before you make that appointment, complete our symptom tracker, which will generate a comprehensive symptom profile you can then review with your healthcare provider to decide if a specific IgE blood test is right for you.

When should allergy testing be repeated?

Since allergies fluctuate, your current allergic triggers could have morphed significantly from those identified through allergy testing just a few years ago. So how often might you retest for allergic triggers?

According to the American College of Allergy, Asthma, and Immunology, there’s no limit to the frequency of testing. However, two years is a logical amount of time to elapse between allergy tests, particularly if you’ve been on an allergy medication and allergen-avoidance plan for two years and your symptoms have returned or worsened.17

When it comes to children, Anaphylaxis UK (a charity offering anaphylaxis-related education) suggests you schedule regular follow-up appointments to track allergy changes and to determine if children may have outgrown their allergies.10

Indeed, given their dynamic tendencies, allergies can seem pretty unpredictable. However, specific IgE blood testing can help your healthcare provider identify current allergic triggers and recommend steps to help you reduce exposure.

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