Allergy & Immunology� July 29, 2026� 9 min read

Allergies: Types, Symptoms, and Modern Treatments

Medically Reviewed by Dr. David Park, Immunology, Johns Hopkins on July 29, 2026. Adheres to strict medical communication criteria.

Dr. Priya Sharma, MD, FACAAI

Allergist/Immunologist, Mount Sinai at Premedice Systems

Summary & Key Takeaway

Allergies are immune system overreactions to normally harmless substances � such as pollen, dust mites, pet dander, certain foods, or insect stings � producing symptoms ranging from sneezing and itchy eyes to life-threatening anaphylaxis. They're incredibly common: 30% of adults and 40% of children have at least one allergic condition. While most allergies cause uncomfortable but manageable symptoms (sneezing, itchy eyes, runny nose), some can be life-threatening � food allergies cause 200,000 emergency room visits per year in the US alone. The allergy landscape is changing: climate change is extending pollen seasons, food allergy prevalence has increased dramatically in recent decades, and new treatments (biologics, oral immunotherapy) are transforming care for conditions that were previously managed only with avoidance. [Premedice](/) can help you evaluate your allergy symptoms and determine whether testing or specialized treatment is needed.

?? Core Insights

Seasonal allergies (allergic rhinitis) are caused by immune responses to airborne pollen � tree, grass, and weed pollen seasons are lengthening due to climate change
Food allergies affect 8% of children and 4% of adults � the most common triggers are peanuts, tree nuts, milk, eggs, wheat, soy, fish, and shellfish
Antihistamines are first-line for mild-to-moderate allergies � newer second-generation antihistamines (cetirizine, loratadine, fexofenadine) cause less drowsiness than older options
Allergen immunotherapy (allergy shots or sublingual tablets) is the only treatment that modifies the underlying allergic disease, reducing symptoms by 80�90% over 3�5 years
Anaphylaxis is a severe, life-threatening allergic reaction requiring immediate epinephrine (EpiPen) � symptoms include difficulty breathing, throat swelling, rapid heartbeat, and dizziness. Call 911 immediately. [Premedice](/) can help you evaluate your allergy symptoms, review testing options, and determine whether immunotherapy is appropriate for you

How Allergies Work: The Immune System's Mistake

Allergies begin with sensitization: the first time you encounter an allergen (say, ragweed pollen), your immune system mistakenly identifies it as dangerous and produces specific antibodies (IgE) against it. These IgE antibodies attach to mast cells in your tissues (nose, eyes, throat, gut, skin). The next time you encounter the same allergen, it binds to those IgE antibodies on mast cells, triggering the mast cells to release histamine and other inflammatory chemicals. Histamine causes the classic allergy symptoms: itching, swelling, mucus production, and smooth muscle contraction.

This response makes evolutionary sense for parasites (which IgE originally evolved to fight) but is wildly inappropriate for pollen or peanuts. Allergic reactions range from mild (sneezing, itchy eyes) to moderate (hives, facial swelling) to severe (anaphylaxis � widespread mast cell activation causing throat swelling, difficulty breathing, blood pressure drop, and potentially death). The severity of the reaction is not predictable � someone who had a mild reaction to a food one time can have anaphylaxis the next time. This unpredictability is why all food allergies should be taken seriously.

Seasonal and Perennial Allergies

Seasonal allergic rhinitis (hay fever) is triggered by airborne pollen: tree pollen (spring), grass pollen (late spring/early summer), and weed pollen (late summer/fall, with ragweed being the most common). Symptoms include sneezing, runny nose (clear, watery discharge), itchy/watery eyes, nasal congestion, and postnasal drip. Perennial allergies occur year-round and are triggered by indoor allergens: dust mites, pet dander, cockroach droppings, and mold. The symptoms are similar but chronic, and may manifest as persistent nasal congestion, recurring ear infections, or chronic sinus problems.

Allergy testing helps identify specific triggers. Skin prick testing (placing small amounts of suspected allergens on the skin and pricking through them) is the most common and sensitive method � results appear within 15�20 minutes as wheal-and-flare reactions. Blood testing (specific IgE levels) is an alternative when skin testing isn't feasible. Understanding your specific triggers allows targeted avoidance strategies and guides immunotherapy decisions. Climate change is lengthening pollen seasons � studies show pollen seasons in North America have extended by 20+ days and pollen counts have increased by 20�30% over the past two decades, making seasonal allergy management increasingly important.

Food Allergies: The Growing Epidemic

Food allergy prevalence has increased dramatically � the number of children with food allergies in the US has increased by 50% since 1997. The most common food allergens are peanuts, tree nuts, milk, eggs, wheat, soy, fish, and shellfish (accounting for 90% of food allergic reactions). Food allergies can cause hives, facial swelling, vomiting, diarrhea, and in severe cases, anaphylaxis. Unlike seasonal allergies, food allergies can cause anaphylaxis on the first known exposure (the person may have been sensitized through a previous, unrecognized exposure).

The management of food allergies is undergoing a revolution. Oral immunotherapy (OIT) � gradually increasing doses of the allergenic food � can raise the threshold for reaction, protecting against accidental exposure. Palforzia (peanut allergen powder) was FDA-approved in 2020 as the first OIT product, reducing the risk of severe reaction from accidental peanut exposure. Other OIT protocols for milk, egg, and other allergens are available through allergy specialists. Epinephrine auto-injectors (EpiPen, Auvi-Q) are essential for anyone with food allergies and should be carried at all times. The OIT approach aims not for 'eating freely' but for protection against accidental exposure � a meaningful safety improvement for those at risk.

Immunotherapy: The Closest Thing to a Cure

Allergen immunotherapy is the only treatment that modifies the underlying allergic disease rather than just managing symptoms. It involves gradually increasing doses of the allergen (via allergy shots or sublingual tablets) to desensitize the immune system. Over 3�5 years, immunotherapy reduces symptoms by 80�90%, reduces medication needs, and can prevent the development of new allergies and asthma in allergic individuals. Effects often persist for years after completing treatment.

Allergen immunotherapy is available in two forms: subcutaneous immunotherapy (SCIT, 'allergy shots') � weekly injections at the allergist's office for the first year, then monthly maintenance � and sublingual immunotherapy (SLIT, 'allergy drops/tablets') � daily administration under the tongue at home. SLIT is available for grass pollen, ragweed, dust mites, and some other allergens. SLIT has a better safety profile (lower risk of anaphylaxis) but is generally less effective than SCIT. For allergic rhinitis, immunotherapy is recommended when symptoms are moderate-to-severe despite medications, when medications cause unacceptable side effects, or when the patient prefers a long-term solution over ongoing medication. For venom allergies (bee, wasp), immunotherapy reduces the risk of anaphylaxis from re-sting from 60% to less than 2%.

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About the Author

Dr. Priya Sharma, MD, FACAAI

Dr. Sharma is a board-certified allergist and immunologist with expertise in allergic diseases and immunotherapy.

Expert Takeaway

Allergies are common and highly treatable. Antihistamines manage mild symptoms, immunotherapy can fundamentally reduce allergic sensitivity, and anaphylaxis requires immediate epinephrine. Proper diagnosis and management prevent complications and improve quality of life.

QFrequently Asked Questions

Q1Can allergies go away on their own?

Some allergies do resolve spontaneously � about 80% of children with milk or egg allergy outgrow it, and many children outgrow wheat and soy allergy. Peanut, tree nut, fish, and shellfish allergies are more persistent � only about 20% of children outgrow peanut allergy. Adult-onset allergies rarely resolve without immunotherapy. Allergy testing can track whether sensitivity is diminishing over time.

Q2Are second-generation antihistamines really non-drowsy?

Second-generation antihistamines (cetirizine/Zyrtec, loratadine/Claritin, fexofenadine/Allegra) cause significantly less drowsiness than first-generation options (diphenhydramine/Benadryl). However, 'less drowsy' doesn't mean 'non-drowsy' for everyone � cetirizine can cause drowsiness in about 10% of users. Fexofenadine is the least sedating option. If drowsiness is a concern, take antihistamines in the evening.

Q3Is allergy testing necessary if I know my triggers?

If you're confident about your triggers and symptoms are well-controlled, testing may not be necessary. However, testing is valuable if: symptoms don't match expected patterns, over-the-counter medications aren't providing adequate relief, you're considering immunotherapy (which requires confirmed sensitization), or you want to know the full scope of your allergies. You may be allergic to things you don't suspect.

Q4Can allergies cause asthma?

Yes. About 40% of people with allergic rhinitis also have asthma � the 'unified airway' concept: upper airway inflammation affects the lower airway. Treating allergic rhinitis aggressively can reduce asthma risk or improve existing asthma control.

Q5Can AI help with allergy management?

AI tools can track your allergy symptoms, correlate them with pollen counts and weather data, identify patterns and triggers, monitor medication effectiveness, and predict high-risk days. Premedice can help you evaluate your allergy symptoms, review testing options, and develop a personalized management plan that addresses both immediate symptom relief and long-term disease modification through immunotherapy.