What Is an Allergist?
(And What to Expect at Your First Visit)

Allergists treat conditions that touch nearly every part of daily life — runny eyes in spring, hives after a meal, asthma flares in cold air, a rash after a new medication. Yet most patients aren't sure what to expect when their doctor finally sends them to one. Understanding what is an allergist before your first visit removes the uncertainty: an allergist is a physician who specializes in diagnosing and treating allergies, asthma, and immune system disorders — conditions where the body overreacts to substances that are otherwise harmless.

Allergists are trained in both internal medicine or pediatrics and then complete additional fellowship training in allergy and immunology. That makes them the right specialist when symptoms are chronic, when the trigger isn't clear, or when first-line treatments aren't working. Knowing what does an allergist do on first visit — and how to prepare — helps you make the most of an appointment that often requires significant prep on your end.

What Is an Allergist?

What is an allergist, specifically? Allergists (also called allergist-immunologists) are medical doctors who complete specialty training focused on how the immune system responds to allergens and how to modify that response. They diagnose the root cause of allergic and immune-related symptoms rather than just managing them with over-the-counter medications.

Conditions an allergist treats include:

• Seasonal and environmental allergies — hay fever, allergic rhinitis, reactions to pollen, dust mites, mold, or pet dander
• Food allergies — identifying specific food triggers and managing reactions, including anaphylaxis risk
• Asthma — both allergic and non-allergic asthma, including diagnosis, trigger identification, and long-term management
• Skin allergies — eczema (atopic dermatitis), contact dermatitis, and chronic hives (urticaria)
• Drug allergies — evaluating reactions to antibiotics, NSAIDs, contrast dyes, and other medications
• Bee sting and insect allergies — diagnosing venom hypersensitivity and prescribing epinephrine or venom immunotherapy
• Immune system disorders — primary immunodeficiencies and conditions where the immune system is underactive rather than overactive

Why Would You Be Referred to an Allergist?

Most allergist referrals happen when symptoms are recurring, unexplained, or not responding to standard first-line treatment. The five most common triggers:

1. Seasonal Symptoms Not Responding to OTC Medications

Antihistamines, nasal sprays, and decongestants help many patients manage seasonal allergies — but when symptoms persist despite consistent OTC treatment, an allergist can identify the specific triggers through testing and offer targeted options including prescription medications or immunotherapy.

2. Suspected Food Allergy

If you or your child has had a reaction that might be food-related — hives, swelling, vomiting, or difficulty breathing after eating — an allergist can confirm or rule out a food allergy through structured testing and help you understand your actual risk level. Unconfirmed food allergies often lead to unnecessary dietary restrictions; confirmed ones may require carrying an epinephrine auto-injector.

3. Asthma Diagnosis or Breathing Difficulties

Allergists diagnose and manage asthma — particularly when it's triggered by allergens, exercise, or environmental factors. If your primary care provider suspects asthma or if existing asthma isn't well-controlled, an allergist can conduct pulmonary function testing, identify triggers, and optimize your treatment regimen.

4. Chronic Hives or Skin Reactions

Hives that recur over weeks or months (chronic urticaria) or persistent eczema that isn't controlled with topical treatments are common reasons for referral. Allergists can evaluate whether an underlying allergic trigger is driving the skin reaction or whether it's immune-mediated.

5. Recurring Sinus Infections

Chronic sinusitis — particularly when accompanied by nasal congestion, post-nasal drip, or loss of smell — often has an allergic component. Allergists evaluate whether untreated environmental allergies are driving recurrent sinus problems and whether treatment could reduce infection frequency.

What Does an Allergist Do on Your First Visit?

What does an allergist do on first visit that's different from a primary care appointment? The focus is on identifying the immune mechanism behind your symptoms — not just treating them. Most first visits follow this four-step structure.

Step 1 — Detailed Allergy and Medical History

Your allergist will ask detailed questions about your symptoms: when they started, how often they occur, what seems to trigger or worsen them, what times of year or day they're worst, and what you've already tried. They'll also ask about your living environment (pets, carpeting, humidity, smoking), your diet, your occupation, your family history of allergies or asthma, and any prior allergic reactions. This history guides which testing is most appropriate — and often suggests the likely diagnosis before any test is run.

Step 2 — Physical Examination

The physical exam in allergy focuses on signs visible in the areas most affected by allergic conditions. Your allergist will examine your nasal passages (for swelling, polyps, or discoloration), your eyes (for redness or swelling), your skin (for eczema, hives, or contact patterns), and your lungs (for wheezing or reduced airflow). They may also check your ears and throat, which are frequently affected by untreated environmental allergies.

Step 3 — Allergy Testing (Skin Prick or Blood Tests)

Allergy testing is the defining feature of what an allergist does — and it's what distinguishes this specialty from primary care. The ACAAI explains that two main testing methods are used:

• Skin prick testing (SPT) — small amounts of common allergens are introduced to the skin surface through tiny punctures, usually on the forearm or back. Results appear within 15–20 minutes as raised, itchy welts at reactive sites. This is the fastest and most comprehensive method for environmental and food allergen screening.
• Blood testing (specific IgE) — measures allergen-specific antibodies in your blood. Used when skin testing isn't possible — for example, if you have severe eczema, can't stop antihistamines, or have a history of severe reactions that make skin testing risky.

Step 4 — Results Review and Treatment Plan

If skin testing is done at the first visit, your allergist may be able to review results the same day and begin outlining a treatment plan. Depending on your specific triggers and symptom severity, treatment options include:

• Allergen avoidance strategies — practical steps to reduce exposure to confirmed triggers
• Medications — prescription antihistamines, nasal corticosteroids, leukotriene modifiers, biologics for severe asthma or eczema, or epinephrine auto-injectors for anaphylaxis risk
• Immunotherapy — allergy shots (subcutaneous immunotherapy) or sublingual drops/tablets that gradually desensitize the immune system over 3–5 years, often reducing or eliminating allergic responses long-term

Questions to Ask Your Allergist at Your First Visit

For a broader question framework applicable to any specialist visit, see our guide on questions to ask your doctor. The allergist-specific questions below are organized by category.

How to Prepare for Your First Allergist Visit

Allergist appointments have more preparation requirements than most specialist visits — particularly around medications. Start with our guide on how to prepare for a doctor's appointment for the general framework, then follow the allergy-specific steps below.

Key preparation steps:

• Stop antihistamines in advance — if skin testing is scheduled, you'll typically need to stop antihistamines 5–7 days before. Call the office when you schedule to confirm exactly which medications to pause and for how long.
• Keep a symptom diary — track when symptoms occur, severity (1–10 scale), what you were doing or eating, environment, and what helped. Even one week of notes is more useful than trying to recall patterns from memory.
• List your known triggers — foods, pets, plants, chemicals, medications, or environments that seem to worsen symptoms, even if you're not certain they're the cause.
• Document your complete medication list — prescriptions, OTC allergy medications, nasal sprays, supplements, and any epinephrine auto-injectors you already carry.
• Gather prior test results — any prior allergy skin tests, blood IgE panels, or pulmonary function tests from other providers.
• Note your family history — allergies, asthma, eczema, or immune conditions in first-degree relatives increase diagnostic likelihood and guide testing priorities.

VisitReady is a free Android app that generates your personalized question list and visit summary automatically — so you walk into your allergist appointment organized and ready.

What to Bring to Your First Allergist Visit

Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for guidance specific to your health situation.