Yes, you can develop allergies as an adult

Maybe going for a walk in the park suddenly leaves you sniffling and sneezing. Or, a food you used to eat without any issues now makes you break out into hives. No, you aren’t imagining it—it’s likely you’re experiencing adult-onset allergies. Even if you didn’t grow up with these sensitivities, they can spring up at any time.

Allergies are “a hypersensitivity to something in the environment that causes our immune system to overreact,” says Carrie Lam, MD, medical director of the Lam Clinic. When you’re allergic to something, it means your immune system classifies that substance as a threat and creates antibodies, which release histamines—to counteract it. The histamines cause reactions like sneezing, itchy eyes, or inflamed skin. The most common type of allergy is seasonal allergies, also known as hay fever, and pollen is the main offender. Other common allergens include animal dander, dust, mold, and certain foods.

What causes adult-onset allergies?

Scientists aren’t quite sure what causes some people to develop allergies while others are fine, but genetics may play a role—you’re more likely to develop allergies if there’s a family history. Allergies often manifest in children, but any allergy can develop later in life. It’s not clear why you can tolerate certain allergens until a point, then develop a reaction in your 20s, 30s, 40s, or even later in life. Or, some people experience allergies as a child, experience remission in their 20s and 30s, then develop a reaction when they are older. The immune system, and how it reacts to certain substances, is constantly changing.    

 Sometimes with environmental allergies, such as pollen or animal dander, it’s not that you suddenly developed adult allergies. Rather, you may have been newly exposed to an allergen that you hadn’t previously encountered, like if you’ve moved to a new city or introduced a pet into your household. Stress can make your body release histamine, making an allergic reaction worse, but it doesn’t cause allergies on its own. 

RELATED: What are the best medications for allergies to pets?

Can you suddenly develop a food allergy?

Nearly half of adults reporting food allergies developed them later in life, according to a study in JAMA. Because our immune systems typically become more tolerant as we age, in the case of adult food allergies, “we don’t think people are developing an allergy as much as they are losing their tolerance of something,” says Alice E.W. Hoyt, MD, host of the Food Allergy and Your Kiddo podcast. You might see this when someone who used to be able to eat peanuts now has an immune response because they’ve lost their peanut tolerance. Or, it could be a cross-reaction to another allergen in food, such as pollen.

What are the symptoms of adult-onset allergies?

How do you know if you’re suffering from adult-onset allergies and not something else? There are three key symptoms to keep in mind for environmental allergies, according to Dr. Hoyt:

1. Itching in your eyes, throat, or skin
2. Running nose, watery eyes, or nasal congestion
3. Sneezing excessively

Itchiness is an important component because the chemical involved in an allergy reaction is histamine, which produces an itchy feeling. Itching is a tell-tale sign that it’s an allergy as opposed to just a runny nose or excessive sneezing, which could be a result of the common cold or irritating particles, like when you walk into a dusty room. In more severe allergy reactions, you may develop facial swelling, hives, diarrhea, vomiting, or difficulty breathing. If those symptoms develop, seek emergency medical help immediately.

“Fever is not a symptom or sign of an allergy reaction,” Dr. Hoyt explains. “That’s definitely a time when you want to talk to your doctor.”

With adult food allergies, while symptoms may vary among people, “reactions happen quickly,” Dr. Hoyt says. “We’re talking a matter of minutes in most people.” That means if you had shrimp for dinner and several nights later developed a rash, it’s unlikely you’re suffering from a food allergy. 

How to treat adult-onset allergies

When should you seek professional help for adult allergies? It’s a good idea to see an allergist if you think you have an allergy. “You want to know what you’re allergic to so you can implement some avoidance strategies,” Dr. Hoyt says. You may have an allergy skin test or blood tests done to help diagnose allergies or to get prescription treatment for severe allergies.
The strategies available for treating adult-onset allergies are the same as treating allergies in kids:

• Avoidance: Avoiding allergic triggers is the most effective way of reducing allergy symptoms, says Dr. Lam. 
• Nasal saline rinses: Using sterile saline, such as Nasaflo Neti Pot, is helpful for rinsing irritants, like pollen, from your nose, so less histamine is released.
• Nasal steroid spray: It can take a few days or weeks for steroid sprays to work, so if you have seasonal allergies, it’s a good idea to start using the spray a few days before allergy season begins. A benefit of using a steroid spray, such as Flonase, is that there are few side effects, as the spray goes directly into your nose and has minimal absorption to the body when used correctly.
• Antihistamine medications: Over-the-counter medications such as Zyrtec or Claritin can be used to treat allergy reactions like sneezing, runny nose, and itchy eyes.  

For more severe allergies, prescription medication or allergy shots may be required.