Our offices are now closed. If you have a life-threatening emergency or urgent clinical need, please hang up and dial 911 or go to your nearest emergency department. For non-urgent issues, please click here for our After-Hours Frequently Asked Questions. If you need to request a prescription refill, please contact your pharmacy directly. You may also call us at 704-372-7900 to leave a general voice message or reach our after-hours answering service.

Online scheduling is now available!!  Book your appointment today at 1 of our 16 convenient locations.

What Causes a Person to Develop Allergies?

Today's Pollen Count

Data last updated: 05/17/2024

Detailed pollen information











Pollen and Mold Levels

Pollen counts are updated daily from February 15 to November 15.
Last updated: October 30, 2023
Richard E. Collins III, MD
Medically reviewed by
Richard E. Collins III, MD

Allergies can come in many shapes and sizes. While some people can enjoy beautiful weather, others avoid going outdoors at all costs. The same situation may occur for people watching others enjoy an endless variety of foods while they must be very selective. Those people who suffer from the incessant symptoms of food or environmental allergies may wonder, why?

Have you ever wondered what causes your stuffy nose and sneezing? It’s not just a string of bad luck; whether your allergy symptoms occur in direct result to the local pollen count, different types of food or your neighbor’s cat, there are certain responses from our immune system that lead to our level of reaction.

In this article, we’ll explain exactly what causes a person to develop allergies, when this can happen, and whether allergic symptoms are worse in adulthood or childhood.

What Are Allergies?

The body’s immune system generates different antibodies to protect us from illnesses. For allergies, the immune system generates Immunoglobulin E, also known as IgE, to aid in combating your allergy symptoms. IgE is a chemical messenger that travels to cells to relay information that a chemical defense against a foreign invader is needed. Allergic individuals have high IgE levels against benign environmental exposures such as pollen or dander. Food can also cause high levels of IgE.

With time, the immune system develops what’s known as immunological memory. Normally this is a helpful immune response which can enable your body to respond more quickly.  This is what allows vaccines to work. In allergy, however, this response is magnified, and your repeat exposures cause recurrent overreactions of the immune system.  This produces an allergic response that may include sneezing, coughing, sniffling and congestion or increased asthma symptoms. IgE antibodies are custom made for each type of allergen. This is why you can be allergic to one or two specific foods or pollens and tolerate others without a problem.

When Does a Person Develop Allergies?

Allergies can develop at any point in a person’s life. One factor that increases your chance is your family history. If one parent is allergic there is a 30-50% chance of their offspring developing allergies. This jumps to 60-80% if both parents are allergic.

In many cases, allergies first present early in life, during infancy or the toddler years. Most of these allergies will be lifelong concerns, although some can resolve on their own.

Can You Develop Allergies Later in Life?

It is certainly possible to develop allergies in adulthood. Adult-onset allergies can occur seemingly out of nowhere due to exposure to new allergens in the environment, family history and changes in the immune system. The most common food allergies in adults are peanuts, fish, shellfish such as shrimp, lobster and tree nuts (almonds, walnuts, pecans and cashews).

There’s no way to avoid getting adult-onset allergies if you’re susceptible to them, since you can’t reasonably expect to know every trigger that could cause an allergic reaction and then avoid it. In addition, there is some recent research that indicates avoiding allergens can make it more likely for an individual to develop allergies, because the immune system is unfamiliar with more substances.

What Are Adult Onset Allergies?

Adult-onset allergies are those allergy symptoms that manifest later in life. This could be anywhere from younger adulthood, such as in a person’s 20s, to a person’s senior years, when they are 70 or 80 years old. Typically, if you lived through your 20s and your 30s without any new allergies, the chances of getting adult-onset allergies diminish.

The strangest part about adult-onset allergies is that you can wake up today irritated by an allergen that didn’t bother you yesterday. You could have been in contact with said allergen every single day for years with no adverse effects. Now, you have a runny nose, itching eyes and uncontrollable sneezing around that allergen.

               See related: How to Keep Your Charlotte Seasonal Allergies in Check

How Do Adult Onset Allergies Develop?

If you’re predisposed to a certain type of allergy, but you’ve never been around that allergen before, it can seem like your symptoms have materialized out of nowhere. Say, for instance, you never had pets growing up. You’re allergic to pet dander, but you’d never know it. Then, your roommate decides to get a dog, and your allergies start going crazy.

So yes, even though it may seem like you just woke up with allergies one day, there’s usually a medical explanation for why it’s happened. Unfortunately, that explanation can be difficult to pinpoint, especially when you’re simply becoming aware of an allergy you may have had for some time.

In other cases, allergies do develop on their own. You may notice changes suddenly, or monitor a gradual shift in your reaction to a specific substance. Adult onset allergies typically develop differently in different people.

What Causes Allergies Later in Life?

Just like childhood allergies, we do not completely understand why some people develop allergies and others don’t. We do know there are complex genetic and environmental factors involved.  Scientists have proposed theories about why allergies occur, including the “hygiene hypothesis” that attributes allergic disease in part to the use of antimicrobials and the high standard of cleanliness in modern societies.

Adults can also present with new-onset environmental allergies. In some cases, the patient may have had a tendency to develop allergies all along, but their environment changed, putting them in more contact with the triggering allergen (for example, a new pet in the home).

What Should I Do if I Develop Adult Onset Allergies?

If you believe you have developed allergies as an adult, avoid any suspected allergens while you are waiting to see your allergist. Your allergist may order some tests such as blood or skin tests to further evaluate your allergies.

If allergy testing confirms a diagnosis of allergy, your allergist will work with you to develop a treatment plan including avoidance measures, medications, and/or other treatment options such as immunotherapy (allergy shots or allergy drops) for environmental allergies.

Are Allergies Worse in Childhood or Adulthood?

Per the American College of Allergy, Asthma & Immunology (ACAAI) and 2013 data, 28 million kids across the United States have allergies. As many as 50 million adults may get reactions to allergens as well.

While more adults have allergies in the United States than children, is there an age group that has it worse? Research that appeared in a 2012 article at MassGeneral Hospital for Children in Massachusetts suggests that adults may be the most at risk for intense, serious symptoms. Adult behaviors such as taking certain medications (like ACE inhibitors, beta-blockers, and NSAIDs, even aspirin) and drinking alcohol may increase risk for severe anaphylaxis. Exercise and having asthma can also increase reaction severity.  Of course, young children who cannot communicate symptoms can also have severe reactions which go unnoticed and progress to dangerous levels.

A severe allergic reaction, which can be triggered by foods or venom (insect stings), is called anaphylaxis. This is a life-threatening emergency condition in which the patient goes into shock, cannot breathe, and may have vomiting, nausea, and skin rashes. Anaphylaxis symptoms can occur instantaneously or sometimes minutes after eating an allergen or being stung. Epinephrine can control cases of anaphylaxis that are caught immediately. The longer the patient goes without treatment, the greater the likelihood that death can occur. For this reason patients with a history of severe anaphylaxis are encouraged to always have an in date epinephrine injector available.

Which Allergies Are Most Common?

While we’ve talked about allergies to things like dander and pollen allergens, these are not the most frequent adult-onset allergies.  Per the American College of Allergy, Asthma & Immunology or ACAAI and data published in 2017 from their Annual Scientific Meeting, the most frequent adult-onset allergies are those to food. In fact, food comprised nearly 50 percent of these allergies!

Which foods triggered the most allergies? Peanuts, shellfish, and tree nuts. The study discovered that Caucasian people were less likely to have peanut and shellfish allergies compared to Hispanic, Asian, and black people of adult age (18 years old or more).

While, back in 2008, the rate of tree nut allergies among adults was only 0.5 percent, it’s jumped by 260 percent. As of 2017, when the study was published, that rate was now 1.8 percent.

In addition, in 2004, only 2.5 percent of adults were allergic to shellfish. Today, that number has seen a 44-percent spike, as 3.6 percent are affected by this seafood allergy in the United States alone.

The American Academy of Allergy, Asthma & Immunology or AAAAI added that younger children aged one through three years old were also getting more food allergies. That said, they had fewer instances of shellfish allergies specifically.

               See related: New Recommendations for Exposing Children to Peanuts

Why does this happen? The verdict is still out. Medical and scientific researchers alike are still working on figuring out why adults have a higher likelihood of getting a shellfish allergy compared to children. One purported reason could be that the allergy is always present, just sitting dormant, like we mentioned above. Another is that since the average person doesn’t eat shellfish in childhood but may in adulthood, their eating habits could lead to allergies.

Can Allergies Be Prevented?

Unfortunately, you cannot prevent the manifestation of adult-onset allergies. As we mentioned, these allergies sometimes spring up where none existed before. Other times, exposure to the allergen triggers a reaction. For those reasons, it’s difficult to say with certainty which triggers you should avoid.

While you can’t always prevent adult-onset allergies, you can treat them as they develop. If, for instance, you notice you get an adverse reaction after eating shellfish or peanuts, you should refrain from eating these foods right away. Instead, set up an appointment with an allergy provider who can test your to see what is causing your symptoms

In the case of food allergies, the best treatment is avoidance. For pet dander, pollen, and other standard allergy triggers, you can try medications, including steroid nasal sprays and antihistamines, to alleviate uncomfortable symptoms. You can also try to keep yourself away from these allergens via lifestyle adjustments.

Can Allergies Stop on Their Own?

A question commonly asked at diagnosis is how likely is it that my allergy will improve with time? The severity and types of symptoms you had at your initial reaction and the number of foods to which you are allergic can help predict your chances of “outgrowing” the allergy. In addition, we know that milk, egg and soy allergies most often improve with time while peanut, tree nut, fish and shellfish are less likely to improve.

It’s not recommended you simply assume that you’ve outgrown a reaction to an allergen; instead, you should visit an allergist for testing. For food allergies, if your test results indicate that it is safe, you will participate in an in office oral food challenge to determine if you still have symptoms.

How Do You Treat Allergies?

Most allergy treatment involves prescription or over-the-counter antihistamines, which treat allergy symptoms. As mentioned, Epinephrine is also used to treat severe allergic reactions.

Other allergy treatments include various forms of immunotherapy, most commonly allergy shots and allergy drops. Both allergy shots and allergy drops expose the immune system to small amounts of one or more allergens at predetermined intervals. Allergen doses start small, then gradually increase. The goal of the treatment is to retrain the immune system to recognize the allergen as not dangerous, decreasing the frequency or severity of allergy symptoms.

Allergy shots and allergy drops are the only current treatment methods that reduce sensitivity to an allergen itself, instead of just treating the allergy symptoms. If you’re interested in either option, speak to an experienced allergist.

Know Where to Go for Allergy Care: Carolina Asthma & Allergy Center

Allergies can begin in childhood, adulthood and anytime in between. If you’re dealing with a new or persistent case of allergies, we encourage you to reach out to us at Carolina Asthma & Allergy. We serve patients throughout North and South Carolina and work with traditional allergy treatment methods as well as allergy shots and allergy drops.

Our board-certified doctors are experts in food allergies, asthma, insect bite allergies and other uncommon, yet often serious allergies that require specialized care. We even offer anaphylaxis prevention and treatment, immunotherapy care and treatments for the lungs, skin, throat, nose, ears, and eyes. To set up your appointment today, contact us today!

Frequently Asked Questions

Can you develop allergies as an adult?

Certainly. You may have had a tendency to develop allergies all along, but your environment changed, putting you in more contact with the triggering allergen (for example, a new pet in the home).

Why do I have allergies now when I didn’t before?

Just like childhood allergies, we do not completely understand why some people develop allergies and others don’t. We do know there are complex genetic and environmental factors involved. Since the average person doesn’t eat shellfish in childhood but may in adulthood, their eating habits could lead to allergies.

What causes allergies to develop?

Scientists are not quite sure, but have hypothesized that it may have to do with the antimicrobules in cleaning products that are commonly used today.

What are the most common allergies in adults?

The most common food allergies in adults are peanuts, fish, shellfish such as shrimp, lobster and tree nuts (almonds, walnuts, pecans and cashews).

Contact Us

To schedule or request an appointment with one of our physicians, please contact us online.