An allergy is the immune system overreacting to something that is harmless to most people. As MedlinePlus puts it, it is a reaction to something that does not bother most others. The trigger, called an allergen, might be tree or grass pollen, dust mites, mold, pet dander, a food, a medication or an insect sting. The body treats it as a threat and releases histamine and other chemicals, which cause the sneezing, itching, swelling and rashes people know as allergy symptoms.
Allergies can start at any age. Many adults tolerate a food, a pet or a medication for years and then begin reacting to it, and some people find that allergies they had as children fade while new ones appear. Genes and environment both seem to play a part. Because of this, a new pattern of symptoms in adulthood deserves a proper look rather than an assumption that it must be a cold that will not go away.
Most allergies are a nuisance rather than a danger, but they can disrupt sleep, work and exercise, they often travel with asthma and eczema, and a small number of people have reactions severe enough to be life-threatening. Our internal medicine physicians evaluate adults with allergy symptoms, sort out what is and is not an allergy, and build a treatment plan. We care for adults only; children should see a pediatrician.
Types of allergies and their symptoms
Seasonal allergies, often called hay fever, follow the pollen calendar: trees in spring, grasses in late spring and summer, and weeds such as ragweed in late summer and fall. Perennial allergies, usually from dust mites, pet dander, mold or cockroaches, cause symptoms year-round and are often worse indoors or at night. Both cause sneezing, a runny or stuffy nose, postnasal drip, itchy eyes, nose and throat, and watery, red eyes. Some people also develop cough, wheezing or tightness in the chest, a sign that allergies are driving asthma.
Food allergies typically cause symptoms within minutes to a couple of hours of eating: hives, itching or swelling of the lips, tongue or throat, vomiting, abdominal pain or diarrhea. Food intolerance, such as lactose intolerance, is different; it causes digestive discomfort but does not involve the immune system and is not dangerous in the same way. Drug allergies, most often to antibiotics such as penicillin, usually show up as a rash or hives, though some reactions are severe. Insect sting allergies can cause large local swelling or, in some people, a whole-body reaction.
The most serious reaction is anaphylaxis. According to Mayo Clinic, it can develop within seconds or minutes and causes hives or flushing, throat swelling, trouble breathing, a weak rapid pulse, nausea or vomiting, and dizziness or fainting.
How we evaluate allergies at NYMD Center
The most useful test is a careful history. We ask what your symptoms are, when they happen, whether they follow the seasons, how they change indoors and outdoors, at home and at work, and what happens when you are exposed to a suspected food, pet or medication. We review your medications, since some drugs cause nasal congestion or rashes of their own, and we examine your nose, eyes, throat, skin, and lungs. If asthma is part of the picture, we evaluate your breathing as well.
When the history points to a specific trigger, testing can confirm it. Two methods are used. A skin test places tiny amounts of common allergens on or just under the skin and checks for a small raised bump after about 15 to 20 minutes, as described by Mayo Clinic. A blood test measures IgE antibodies to specific allergens and is useful when skin testing is not a good option, for example in people with extensive rash or those at risk of a strong skin reaction. For suspected food problems, a supervised elimination and reintroduction of the suspected food can help clarify the cause. We do not perform allergy testing in our office. When testing would change your treatment, we refer you to an allergist, who chooses between skin and blood testing.
A positive test on its own does not prove an allergy; many people have positive results to substances that cause them no symptoms. We interpret results against your history.
Treatment options
Avoiding triggers
Reducing exposure is the foundation. For pollen, that means keeping windows closed on high-count days and showering after time outdoors. For dust mites, allergen-proof bedding covers and hot-water washing help. For food and drug allergies, strict avoidance is the treatment, and we make sure the allergy is documented in your record. Our allergy management page covers these long-term steps in more detail.
Antihistamines
Non-sedating antihistamine tablets relieve sneezing, itching and runny nose and work within hours. They help less with congestion. Older antihistamines cause drowsiness and are best avoided during the day, particularly in older adults.
Nasal steroid sprays
For persistent nasal symptoms, a steroid nasal spray is usually the most effective single medication. It reduces inflammation, congestion and drip, but it takes days of regular use to reach full effect, so it works best taken daily rather than only on bad days. Nosebleeds and irritation are the most common side effects, and correct technique helps avoid them.
Eye drops and other medications
Antihistamine eye drops ease itchy, watery eyes. Other options include antihistamine nasal sprays and, for some patients with asthma, a leukotriene blocker. Decongestant sprays should be used for only a few days, since longer use causes rebound congestion.
Immunotherapy
When symptoms persist despite medication, or when you want to reduce long-term reliance on it, immunotherapy retrains the immune system with gradually increasing doses of the allergen. It is given as regular shots over several years, or for certain grass, ragweed and dust mite allergies as a daily tablet under the tongue. We refer appropriate patients to an allergist for this treatment.
Allergies and asthma
Allergic rhinitis and asthma often occur together, and poorly controlled nasal allergies can make asthma harder to control. If you cough, wheeze or feel short of breath with allergy season, tell us. See our asthma and COPD page for how we evaluate and treat breathing problems.
What to expect at your visit
Bring a list of your medications and any over-the-counter allergy products you use, notes on when symptoms occur, and any prior allergy test results. If testing may be done, we will tell you in advance which antihistamines to stop and for how long, since they can blunt results; do not stop asthma or other prescription medicines without asking. You will leave with a working diagnosis, a treatment plan and, where needed, a plan for testing or referral.
When to seek care urgently
Call 911 for signs of anaphylaxis: swelling of the lips, tongue or throat, trouble breathing or swallowing, wheezing, hives spreading across the body, vomiting, dizziness or fainting after a food, medication or sting. If you have an epinephrine auto-injector, use it right away and still call 911, because symptoms can return. Anyone who has had a severe reaction should carry epinephrine and know how to use it.
Questions patients ask
Can you develop allergies as an adult?
Yes. Allergies can begin at any age, including to foods, pets or medications you tolerated for years. Some childhood allergies also fade over time. If you notice a new pattern of sneezing, itching, hives or congestion, especially if it follows the seasons or a specific exposure, it is worth an evaluation rather than assuming it is a lingering cold.
How can I tell allergies from a cold?
Colds usually come with fatigue, sometimes a low fever or body aches, and clear up within a week or two. Allergies cause itching of the eyes, nose or throat, sneezing and clear drainage without fever, and they last as long as the exposure continues or follow the same season each year. If symptoms drag on for weeks, allergies are a likely cause.
What is the difference between a skin test and a blood test for allergies?
A skin test places tiny amounts of allergens on or just under the skin and reads the reaction in about 15 to 20 minutes. A blood test measures IgE antibodies to specific allergens in a lab and is useful when skin testing is not suitable, such as with extensive rash. Both must be interpreted alongside your symptoms, since positive results do not always mean a true allergy.
Do I need to stop my allergy medicine before testing?
Usually yes for antihistamines, because they can suppress skin test results. How long to stop depends on the specific medication, so we will give you instructions before your appointment. Blood tests are not affected in the same way. Do not stop asthma inhalers or other prescription medications on your own; ask us first.
What should I do if I think I am having anaphylaxis?
Use your epinephrine auto-injector if you have one and call 911 right away. Warning signs include throat or tongue swelling, trouble breathing, widespread hives, vomiting, dizziness or fainting shortly after a food, medication or insect sting. Go to the emergency room even if you feel better, because symptoms can return hours later.