Allergy
What is Allergy?
An allergy is your immune system's reaction to a substance that is usually harmless to most people. When you have an allergy, your body treats certain things like pollen, pet dander, or foods as dangerous invaders. Your immune system then releases chemicals like histamine to protect you, which causes uncomfortable symptoms.
Allergies affect more than 50 million Americans each year. They can develop at any age, even if you never had them before. Some allergies are mild and just annoying, while others can be severe or life-threatening. Common allergens include pollen, mold, dust mites, pet dander, insect stings, foods like peanuts or shellfish, and certain medications.
Your body produces a specific antibody called Immunoglobulin E when exposed to allergens. This antibody triggers the release of chemicals that cause allergy symptoms. Understanding what triggers your allergies helps you avoid them and manage your symptoms better.
Symptoms
- Sneezing and runny or stuffy nose
- Itchy, watery, or red eyes
- Itchy skin, hives, or rashes
- Coughing or wheezing
- Swelling of the lips, tongue, face, or throat
- Stomach pain, nausea, vomiting, or diarrhea from food allergies
- Shortness of breath or chest tightness
- Fatigue or difficulty concentrating
Some people with mild allergies may not notice symptoms until exposure increases. Severe allergic reactions, called anaphylaxis, can cause difficulty breathing, rapid pulse, and a dangerous drop in blood pressure. Anaphylaxis is a medical emergency that requires immediate treatment with epinephrine.
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Causes and risk factors
Allergies develop when your immune system mistakenly identifies a harmless substance as a threat. Genetics play a significant role in allergies. If one or both parents have allergies, you are more likely to develop them too. The exact reason why some people develop allergies and others do not is still not fully understood by scientists.
Common risk factors include family history of allergies or asthma, being a child, and having asthma or another allergic condition. Environmental factors like pollution, tobacco smoke, and early childhood infections may also influence allergy development. The hygiene hypothesis suggests that reduced exposure to germs in early childhood might increase allergy risk, though this theory is still being studied.
How it's diagnosed
Allergies are diagnosed through a combination of medical history, physical examination, and testing. Your doctor will ask about your symptoms, when they occur, and potential triggers. They may recommend skin prick tests, where small amounts of allergens are placed on your skin to see if a reaction occurs. Blood tests can also help identify allergies by measuring Immunoglobulin E levels in response to specific allergens.
Talk to a doctor about specialized allergy testing if you suspect you have allergies. While basic Immunoglobulin E testing can indicate an allergic response, identifying specific allergens usually requires more targeted tests. Keeping a symptom diary can help you and your doctor identify patterns and potential triggers before testing.
Treatment options
- Avoid known allergens whenever possible
- Use air purifiers and keep windows closed during high pollen seasons
- Wash bedding weekly in hot water to reduce dust mites
- Remove shoes at the door and shower after being outside
- Over-the-counter antihistamines to reduce symptoms
- Nasal corticosteroid sprays to reduce inflammation
- Decongestants for short-term relief of nasal congestion
- Immunotherapy, or allergy shots, to build tolerance over time
- Carry an epinephrine auto-injector if you have severe allergies
- Work with a doctor to create an allergy action plan
Frequently asked questions
Allergies and colds share similar symptoms like sneezing and runny nose, but they have different causes. A cold is caused by a virus and usually goes away in 7 to 10 days. Allergies are caused by your immune system reacting to allergens and last as long as you are exposed to the trigger. Allergy symptoms often include itchy eyes and nose, which are less common with colds.
Yes, you can develop allergies at any age, even if you never had them before. Adult-onset allergies are common and can occur when your immune system changes. Moving to a new area with different plants or getting a pet can trigger new allergies. Changes in your environment, stress levels, or overall health may contribute to developing allergies later in life.
Blood tests measure Immunoglobulin E antibodies in your blood to identify allergic responses. When your body encounters an allergen, it produces specific IgE antibodies. These tests can help confirm if you have allergies and sometimes identify specific triggers. Blood tests are especially useful for people who cannot undergo skin prick tests due to skin conditions or certain medications.
Yes, hay fever is another name for seasonal allergic rhinitis. It occurs when your immune system reacts to outdoor allergens like tree, grass, or weed pollen. Despite its name, hay fever does not cause a fever and is not caused by hay. Symptoms include sneezing, runny nose, and itchy eyes, typically during spring, summer, or fall.
Yes, allergies can make you feel tired and drained. When your immune system fights allergens, it releases chemicals that can cause inflammation and fatigue. Poor sleep from nasal congestion or breathing difficulties also contributes to tiredness. Some allergy medications, particularly first-generation antihistamines, can cause drowsiness as a side effect.
Anaphylaxis is a severe, life-threatening allergic reaction that requires immediate medical attention. Symptoms include difficulty breathing, swelling of the throat or tongue, rapid pulse, dizziness, and a sudden drop in blood pressure. Skin reactions like hives and stomach symptoms may also occur. If you suspect anaphylaxis, call 911 and use an epinephrine auto-injector immediately if available.
While diet cannot cure allergies, certain foods may help reduce inflammation and support immune health. Foods rich in omega-3 fatty acids, vitamin C, and quercetin may help manage symptoms. Avoiding foods you are allergic to is critical if you have food allergies. Some people with pollen allergies experience cross-reactivity with certain raw fruits and vegetables, known as oral allergy syndrome.
The frequency of allergy testing depends on your symptoms and treatment plan. If you have new or worsening symptoms, testing can help identify triggers. Retesting may be helpful if your allergies change over time or if you complete immunotherapy. Your doctor can recommend the best testing schedule based on your individual needs and medical history.
Yes, air purifiers with HEPA filters can help reduce indoor allergens like dust, pet dander, and pollen. They work by trapping tiny particles that trigger allergy symptoms. Air purifiers are most effective in bedrooms and other spaces where you spend a lot of time. However, they should be used along with other strategies like regular cleaning and reducing allergen sources.
Some allergies, especially childhood food allergies, may resolve over time as the immune system matures. Many children outgrow allergies to milk, eggs, wheat, and soy. However, allergies to peanuts, tree nuts, fish, and shellfish are more likely to persist. Environmental allergies like pollen or pet dander may improve, worsen, or stay the same throughout your life.