By Caroline C. Aquino, MD, FPPS, DPSAAI
Allergy 101 — A Patient Guide to Symptoms, Diagnosis, and Management
Summary
Allergy is an exaggerated immune response to a usually harmless substance called an allergen. In people with allergies, the immune system mistakenly identifies these substances as harmful and reacts excessively.
Table of Contents
What is allergy?
Allergy is an exaggerated immune response to a usually harmless substance called an allergen. In people with allergies, the immune system mistakenly identifies these substances as harmful and reacts excessively.
Allergens are commonly proteins that enter the body through inhalation, ingestion, injection, or skin contact.
Common allergens include:
Foods
(milk, eggs, peanuts, tree nuts, soy, wheat, fish, shellfish, sesame)
Airborne substances
(pollen, dust mites, molds, pet dander)
Medications
Insect stings
Latex and certain materials
Not everyone exposed to these substances develops allergies. However, in susceptible individuals, exposure can trigger symptoms that range from mild to severe.
What happens during an allergic reaction?
When a person with allergies is exposed to an allergen, the immune system produces Immunoglobulin E (IgE) antibodies specific to that substance. These antibodies cause the release of histamine and other inflammatory chemicals.
This release leads to common allergy symptoms such as:
Itching
Redness
Swelling
Sneezing
Runny or blocked nose
Coughing
What are the symptoms of allergy?
Symptoms vary depending on the part of the body affected.
Respiratory Symptoms:
Sneezing
Runny or stuffy nose
Itchy or watery eyes
Wheezing
Shortness of breath
Skin Symptoms:
Itchy Rashes
Hives
Swelling of the lips, eyelids, or face
Gastrointestinal Symptoms (common in food allergy)
Abdominal pain
Vomitting
Diarrhea
Severe Allergic Reaction (Anaphylaxis)
Anaphylaxis is a life-threatening allergic reaction and is a medical emergency.
Warning signs may include:
Difficulty breathing
Tightness or swelling of the throat
Hoarseness
Dizziness or fainting
Sudden drop in blood pressure
Seek emergency medical attention immediately if any of these symptoms occur. Early treatment can save lives.
How are allergies diagnosed?
If allergy is suspected, consultation with a physician, preferably a specialist in allergy and immunology, is recommended.
Diagnosis is based on a detailed medical history and may include:
Skin Prick Test
A small amount of suspected allergen is placed on the skin to check for a reaction.
Blood Test
Measures specific IgE antibodies to certain allergens.
Oral Food Challenge
Conducted under close medical supervision to confirm food allergies when necessary.
Allergy testing should be guided by a doctor. Self-requested testing without proper medical evaluation is not recommended.
How are allergies managed?
The primary step in managing allergies is identifying and avoiding known triggers.
Medications may be prescribed by a doctor to help control symptoms and reduce inflammation. These may include:
Antihistamines
Leukotriene modifiers
Intranasal corticosteroids for allergic rhinitis
Inhaled corticosteroids for asthma
Short courses of oral corticosteroids in selected cases
Epinephrine for individuals at risk of severe allergic reactions
Epinephrine should be used as prescribed for severe reactions, and emergency medical care must still be sought immediately after use.
In some persistent cases of allergic rhinitis or asthma, allergen immunotherapy (allergy shots or sublingual therapy) may be recommended to gradually reduce sensitivity to specific allergens.
Treatment plans should always be individualized and supervised by a healthcare professional.
When should you see a doctor?
You should consult a doctor if:
- Symptoms are persistent or worsening
- Symptoms interfere with daily activities or sleep
- There are signs of asthma, such as wheezing or shortness of breath
- There is a history of severe allergic reaction
- Allergy symptoms occur in young children
Early evaluation helps prevent complications and allows proper management. Avoid self-medication for persistent or severe symptoms without medical advice.
Regular follow-up is important to keep allergies under control and reduce the risk of worsening episodes.
Key Message
Allergies are common and manageable. Early recognition of symptoms, proper diagnosis, trigger avoidance, and timely consultation with a healthcare professional are essential in preventing complications and improving quality of life.
If you suspect that you or your child may have allergies, seek medical evaluation for appropriate guidance and care.
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