An allergy is an overreaction of the immune system to substances that are normally harmless, and allergy testing helps identify which of these substances is behind your symptoms. These substances are called allergens. Pollen, house dust mites, pet dander, mold, certain foods and medications are common allergens, and which one a person reacts to varies.

An antibody called IgE plays a key role in the allergic response. When you meet an allergen, IgE triggers cells called mast cells. Substances they release, such as histamine, cause itching, sneezing, redness and swelling.

Allergies can appear at any age. Some childhood food allergies fade, while new allergies to pollen, dust or chemical smells can develop later in life.

Family history matters: children of parents with allergies are more likely to develop them, and environment and living conditions also play a part.

Symptoms depend on the allergen and which part of the body is affected. Common allergic conditions include:

• Allergic rhinitis: Sneezing, a runny or blocked nose and itching. Hay fever belongs to this group.
• Allergic conjunctivitis: Itchy, red, watery and swollen eyes.
• Atopic dermatitis (eczema): Dry, itchy, red skin.
• Urticaria (hives): Itchy, raised patches on the skin.
• Allergic asthma: Cough, wheezing and shortness of breath.
• Food allergy: Itching in the mouth, lip swelling, vomiting, diarrhea or a skin rash.

Allergic rhinitis is often mistaken for a cold, but there is usually no fever; symptoms flare when you meet the allergen and can last for weeks.

Swelling of the lips, tongue or throat, difficulty breathing, a widespread rash and dizziness may be signs of a severe allergic reaction. This is called anaphylaxis and needs emergency care: call 112 right away.

Testing starts with an examination and health history: when symptoms started, where they get worse and what you eat. The tests you need are then planned:

• Skin prick test: Drops of suspected allergens are placed on the skin, which is lightly pricked with a fine tip. Any redness and raised bump is then assessed.
• Blood tests: Total and specific IgE levels in the blood are measured.
• Other tests: A patch test or lung function tests may be done if needed.

Results are interpreted together with your symptoms, not alone. The doctor decides which allergens to test, and when, based on your complaints. When needed, you are referred to an allergy and immunology specialist.

A food allergy is different from a food intolerance, which usually affects digestion rather than the immune system (lactose intolerance, for example). The distinction matters for the right eating plan.

The first and most important step is finding the allergen behind your symptoms and avoiding it as much as possible. If you have a food allergy, your diet is adjusted accordingly. Medication recommended by an allergy specialist and, if needed, allergy shots (immunotherapy) are the foundation of treatment.

At our clinic in Nişantaşı, Istanbul, supportive options may be planned alongside this treatment if the doctor finds them suitable:

• Nutrition: A personalized eating plan that leaves out trigger foods.
• Gut health: If an imbalance in gut flora is suspected, you may be assessed for dysbiosis.
• Ozone therapy: A course of major ozone therapy may be planned to help ease symptoms.
• Detox program: A lifestyle and nutrition-based detox program may be added to the plan.

Suitability depends on the type of allergy, symptom severity and your general health. For allergies, an ozone course is usually planned as at least 12 sessions, and once you feel better, maintenance sessions may be given at intervals. Scientific evidence on ozone for allergies is limited, and the response varies from person to person.

Before ozone therapy, tests such as a G6PD enzyme level and a blood count are requested. Supportive treatments continue alongside your allergy medication; any change to that medication is the decision of the doctor who prescribed it.

It is not always possible to prevent allergies entirely, but some steps may ease symptoms by reducing contact with allergens:

• Pollen season: Keep windows closed when pollen levels are high, wash your face when you come indoors and follow the local pollen calendar to plan ahead.
• House dust: Wash bedding often in hot water and cut down on carpets and heavy curtains.
• Pets: Keep pets out of the bedroom.
• Mold: Control humidity at home and air rooms regularly.
• Foods: Read labels carefully for any food you are allergic to.

People who have had a severe allergic reaction should carry the emergency medication their doctor has prescribed. For lifestyle advice, see our page on immune system support.