Can You Develop Food Allergies as an Adult?

An allergy is the immune system’s mistaken reaction to an innocuous protein as if it were a dangerous pathogen. The immune system mounts a full-scale assault on the protein, causing unpleasant symptoms in the process, from itchiness and hives to anaphylactic shock, a life-threatening condition during which breathing becomes difficult.

You might think that developing allergies is something that happens just to kids or teens, but many first-time allergy symptoms appear in adults.

At Allergy Asthma & Immunology Institute, Dr. Laura Ispas and our team diagnose and treat patients of all ages with food allergies, and that includes adults who are first-time sufferers. Here’s what we want you to know about adult-onset food allergies and why they happen.

Common food allergy symptoms

Symptoms of an allergic reaction to food may involve your skin, GI tract, cardiovascular system, and/or respiratory tract. They can present in one or more of the following ways:

• Itchiness (in your mouth or all over your body)
• Rash
• Hives
• Vomiting and/or stomach cramps
• Shortness of breath
• Wheezing
• Tight, hoarse throat; trouble swallowing
• Tongue swelling, affecting the ability to talk or breathe
• Weak pulse
• Pale or blue coloring of skin
• Dizziness or feeling faint

Anaphylaxis is also a possibility. This potentially life-threatening reaction impairs breathing and sends the body into shock. It needs to be treated immediately, and it’s usually controlled by an injection of epinephrine. 

People with severe allergies often carry an EpiPen® or something like it to dose themselves when they feel the symptoms coming on.

Most food-related allergy symptoms occur within two hours of eating, but they can start within minutes. In rare cases, the reaction can be delayed by 4-6 hours or even longer. These delays are usually seen in children who develop eczema as a symptom.

Major allergens

Of foods that cause allergic responses, only eight are responsible for 90% of cases. Congress passed the Food Allergen Labeling and Consumer Protection Act of 2004, which identified the allergens and required manufacturers to label products to alert consumers who might be affected. 

The eight include:

• Milk
• Eggs
• Fish
• Crustacean shellfish
• Tree nuts
• Peanuts
• Wheat
• Soybeans

On April 23, 2021, the act was amended to include sesame as the ninth major food allergen. That change went into effect on January 1, 2023.

Developing food allergies as an adult

Research indicates that about 10% of American adults have at least one food allergy, and half of those allergies developed during adulthood. Why does that happen?

One reason is that certain food allergies can be related to other allergies you know you have. For example, people with allergies to shrimp are often the same people who have a dust mite allergy. They know they’re allergic to dust mites, but, over time, they discover they can’t eat shrimp without having a reaction. 

It’s not known how the allergies are related, only that they are.

It’s the same case for people who have allergies to airborne allergens. A ragweed allergy, for example, may also produce oral allergy symptoms to bananas, watermelon, and cantaloupe. 

And allergies to birch tree pollen can produce oral reactions to stone fruits such as peaches, plums, and cherries.

The reason behind this is that, at the molecular level, the substances are similar. Your body, therefore, sees the foods as similar invaders to the ragweed and mounts a defense against them. 

Another reason for adult-onset food allergies may be a case of long-term exposure. Adults could be genetically predisposed to the allergy from the time they were kids, but it wasn’t until they had years of exposure to the allergen that their immune system was convinced there was a problem and triggered a response.

Adult-onset food allergies can also develop after a period of intermittent exposure. If you eat a type of food fairly consistently, your body can build up a tolerance to it, but if you stop eating the food for a while, the tolerance can fade. The next time you ingest it, it can provoke an allergic reaction.

If you’re an adult who has developed a food allergy, come into our Leesburg, Virginia, office for skin testing to confirm that you have an allergy and to get treatment to manage the symptoms. Call us at 571-399-5132, or request your appointment online today through our online portal.