Why you’re suddenly allergic to everything

At least one in three adults in the U.S. has allergies.

If you didn't have allergies as a child, you might be surprised when you suddenly have uncontrollable sneezing in spring, break out in hives after petting a cat or experience swelling in your mouth after eating a favorite food.

Late-onset allergies — ones that occur for the first time in adulthood — are quite common. Here's what you should know about late-onset allergies, how they're diagnosed and treatment options to manage them.

What are allergies?

Allergies are an immune system reaction to something you touch, eat, breathe or come into contact with in another way. At least one in three adults in the U.S. has allergies.

An allergic response can affect your skin, digestive system, respiratory system, eyes or entire body. Some allergic reactions are minor while others are quite serious and require immediate or ongoing medical attention.

Examples of mild allergic reaction include:

• Itchy, watery eyes
• Itching, rash or hives on one part of the body
• Stuffy nose, sneezing

In severe cases, allergic reactions can quickly develop into anaphylaxis, a medical emergency. If you notice any of the following signs, call 911:

• Nausea and vomiting
• Abdominal pain and diarrhea
• All over rash or hives
• Difficulty swallowing
• Trouble getting a breath
• Flushing of the face
• Chest discomfort or heart palpitations
• Swelling of the face or mouth
• Difficulty breathing
• Unresponsiveness, confusion or loss of consciousness

Even if you have a mild reaction the first time, you may experience more extreme symptoms the next time you are exposed to that allergen. Talk to your healthcare team if you experience new allergies or symptoms.

Types of adult-onset allergies

Allergies can start at any time in life, including adulthood. This includes:

• Seasonal allergies: These are the most common allergies in adulthood, with one in four adults experiencing hay fever or other respiratory reactions to breathing in the pollen released by trees and other plants.
• Asthma: Many adults develop asthma either as part of seasonal allergies or in response to other substances that they breathe in, including mold and pollution.
• Skin allergies: Allergies that cause rashes or skin reactions (including eczema and other itchy rashes) are also common in adults.
• Food allergies: One in 10 adults has a food allergy, and at least half of these allergies developed after age 20. The most common late-onset food allergy is to fish (especially shellfish), but it's not uncommon to develop reactions to wheat, milk, nuts and soy in adulthood.

Late-onset allergies on the rise

Researchers and other experts have several theories about why more people are experiencing allergic reactions for the first time as adults:

• Family history: If allergies run in your family, you are more likely to develop them as an adult even if you didn't have them as a kid.
• Longer, more intense allergy seasons: In many areas of the country, allergy seasons are now three weeks longer than in the past, meaning trees and other plants are giving off more pollen for a longer time. The chance of an allergic reaction increases with longer exposures to the offending substance.
• Change of geography: If you move to a new area, you may come in contact with plants and other substances that you haven't encountered before.
• Hormonal changes: Studies show that women have more allergic responses than men, especially during times of hormonal fluctuations, such as during pregnancy or menopause.
• Repeated exposure: You may not have noticed a mild allergic response in the past, but more prolonged or intense exposure may bring on a more serious reaction.
• Infections: Viral or bacterial infections can "flip a switch" and cause allergies that were not present before. Some types of tick bites can result in alpha-gal syndrome, which causes an allergic response to red meat.
• Gastroesophageal reflux (GERD) and other digestive disorders: Researchers are studying the relationship between excess acid in the digestive system and allergy symptoms. Having GERD may worsen respiratory allergies, including asthma symptoms.
• Medications: Excessive use of antibiotics may increase the risk of allergic reactions. In addition, many adults take medications to treat another condition, and some may develop an allergy to one or more of those medications.
• Lifestyle factors: Smoking, alcohol use, stress, air pollution and obesity are all linked with a higher risk of allergic reactions.

What to do if you develop late-onset allergies

Symptoms of late-onset allergic reactions can be mild, moderate or serious. Start by tracking your symptoms, as this will help your doctor identify the allergen more easily. Pay attention to food labels and try to keep track of triggers that seem to impact your allergies.

If you suspect an allergic reaction, try to identify the substance causing the allergy and remove it if possible. As much as possible, stay calm, because anxiety can make symptoms worse.

In mild cases, your doctor may recommend an over-the-counter antihistamine. For skin reactions, cold compresses or cortisone cream may also be recommended to reduce itching and discomfort.

In more serious cases, or for ongoing or recurrent allergies, your doctor may recommend immunotherapy (typically in the form of allergy shots) to help reduce symptoms in the future.

Hope for late-onset allergies

Although late-onset allergies can be surprising and uncomfortable, they don't have to disrupt your life. Your healthcare team or an allergist can help figure out what caused the reaction and recommend treatment so you can get back to your regularly scheduled life.