It is possible to develop new allergies or experience a return of childhood allergies during adulthood. While many people associate allergies primarily with childhood, the immune system is dynamic and can develop new sensitivities at any point in life.
Why Allergies Emerge in Adulthood
The immune system’s ability to recognize and respond to substances can change throughout a person’s life, leading to new sensitivities. As individuals age, their immune system undergoes shifts that may make it more reactive to previously harmless substances, resulting in allergic responses that were not present in earlier years.
New exposures to allergens are a common reason for adult-onset allergies. Moving to a different region, changing jobs, or acquiring a new pet can introduce novel allergens. The immune system may then identify these substances as threats, triggering an allergic reaction.
Genetic predisposition also plays a role. While allergies often have a hereditary component, susceptible genes might express themselves later in life. For instance, if one parent has allergies, their child has a 30-50% chance of developing them, increasing to 60-80% if both parents are allergic.
Hormonal shifts can influence immune responses and contribute to adult allergies. Changes during pregnancy or menopause can alter the immune system’s balance, potentially leading to new sensitivities. Some women report experiencing allergies for the first time during or shortly after pregnancy.
Cross-reactivity can cause an existing allergy to one substance to lead to a new allergy to a seemingly unrelated substance. This occurs because proteins in different allergens share similar structures. For example, individuals allergic to certain pollens might develop an allergy to specific fruits or vegetables, known as oral allergy syndrome.
Types of Allergies Commonly Seen in Adults
Adults frequently develop new sensitivities to foods like shellfish, tree nuts, peanuts, and fin fish. These are among the most common food allergens to emerge in adulthood. Oral allergy syndrome, causing symptoms like itching or swelling in the mouth after eating raw fruits or vegetables, can also develop due to cross-reactivity with pollen.
Environmental allergens can also trigger new allergies in adults. These include seasonal pollens from trees, grasses, and ragweed, appearing as hay fever symptoms. Year-round allergies to dust mites, pet dander, or mold spores can also develop, even to pets previously tolerated.
New sensitivities to medications are another type of allergy. Any medication can trigger a reaction, but antibiotics, particularly penicillin and sulfa drugs, and NSAIDs (aspirin) are common culprits. Reactions can range from skin rashes to more severe responses.
Insect sting allergies, particularly to bee or wasp venom, can develop into severe reactions in adults, even if previous stings caused mild local swelling. These reactions can escalate and affect the entire body.
Contact dermatitis, a skin reaction, commonly affects adults who develop new sensitivities to chemicals, metals like nickel (found in jewelry), fragrances, or preservatives. This allergy results from direct skin contact, causing an itchy rash that may appear hours or days after exposure.
Identifying Symptoms and Next Steps
Common allergic reactions can manifest as skin rashes, hives, itching, or swelling. Other symptoms include nasal congestion, sneezing, a runny nose, watery or itchy eyes, and a scratchy throat. Food allergies might also present with digestive issues like nausea, vomiting, or diarrhea.
Severe reactions, known as anaphylaxis, require immediate medical attention. Signs can appear rapidly, often within minutes of allergen exposure. These include difficulty breathing, wheezing, a sudden drop in blood pressure, a rapid or weak pulse, dizziness, confusion, or fainting. Swelling of the throat, tongue, or lips is also a serious indicator.
If new or worsening symptoms suggest an allergy, consult a healthcare professional, especially an allergist. They can determine if symptoms are due to an allergy or another condition, as some mimic those of a common cold.
Diagnosis typically involves a thorough review of medical history and symptoms. Diagnostic methods include skin prick tests, where small amounts of allergens are applied to the skin to observe a reaction. Blood tests, which measure immunoglobulin E (IgE) antibodies specific to allergens, can also be used. In some cases, an allergist might recommend an elimination diet for suspected food allergies.
Management strategies involve avoiding known allergens. Medications like antihistamines, nasal steroid sprays, and decongestants can relieve symptoms. For severe cases, an epinephrine auto-injector (EpiPen) may be prescribed, and patients are advised to carry it. Immunotherapy, such as allergy shots or sublingual tablets, can also be a long-term treatment to help the body develop tolerance to specific allergens.