# Allergy: Causes, Symptoms and Treatment

Allergy is a condition that occurs when the immune system overreacts to a normally harmless substance, such as pollen, dust, food or animal dander. The immune system produces antibodies that bind to the substance and trigger the release of chemicals such as histamine, which cause inflammation and various symptoms. Allergy can affect different parts of the body, such as the nose, eyes, skin, lungs or digestive system.

The causes of allergy are not fully understood, but they are likely to involve both genetic and environmental factors. Some people are born with a tendency to develop allergies, which may run in families. However, not everyone with a genetic predisposition will develop allergies, and some people may develop allergies later in life due to exposure to certain substances or changes in the immune system. Some factors that may increase the risk of developing allergies include:

- Having a family history of allergies or related conditions such as asthma or eczema

- Being exposed to allergens at an early age or in large amounts

- Having other medical conditions that affect the immune system, such as autoimmune diseases or infections

- Living in a polluted or urban environment

- Having a low diversity of gut bacteria

- Smoking or being exposed to secondhand smoke

- Being overweight or obese

The symptoms of allergy vary depending on the type and severity of the reaction, as well as the part of the body affected. Some common symptoms include:

- Sneezing, runny or stuffy nose, itching or burning sensation in the nose (allergic rhinitis)

- Red, itchy, watery or swollen eyes (allergic conjunctivitis)

- Itchy, red, dry or scaly skin, hives, eczema or contact dermatitis (allergic dermatitis)

- Wheezing, coughing, shortness of breath, chest tightness or asthma (allergic asthma)

- Nausea, vomiting, diarrhea, abdominal pain or cramps (food allergy)

- Swelling of the lips, tongue, throat or face, difficulty swallowing or breathing, dizziness, fainting or anaphylaxis (severe allergic reaction)

The diagnosis of allergy is based on the medical history, physical examination and allergy tests. The medical history involves asking questions about the symptoms, their onset, duration and triggers, as well as any personal or family history of allergies or related conditions. The physical examination involves looking for signs of allergic inflammation in the affected areas. The allergy tests involve exposing a small area of the skin or blood to different allergens and measuring the immune response. The most common types of allergy tests are:

- Skin prick test: A small amount of allergen is pricked into the skin and the reaction is observed after 15 to 20 minutes. A raised red bump indicates a positive result.

- Intradermal test: A small amount of allergen is injected under the skin and the reaction is observed after 15 to 20 minutes. A larger red bump indicates a positive result.

- Patch test: A patch containing allergen is applied to the skin and left for 48 hours. The skin is then checked for any signs of irritation or rash.

- Blood test: A blood sample is taken and analyzed for specific antibodies against allergens. A high level of antibodies indicates a positive result.

The treatment of allergy aims to relieve the symptoms and prevent future reactions. The main strategies are:

- Avoidance: The best way to prevent allergic reactions is to avoid contact with the allergens that cause them. This may involve reading labels carefully, asking about ingredients in restaurants or other places, wearing protective clothing or masks, using air filters or humidifiers at home or work, washing hands frequently and keeping pets out of bedrooms.

- Medication: Various medications can help reduce the inflammation and symptoms caused by allergies. These include antihistamines (which block histamine), decongestants (which shrink swollen nasal passages), corticosteroids (which reduce inflammation), leukotriene modifiers (which block leukotrienes), mast cell stabilizers (which prevent mast cells from releasing chemicals) and epinephrine (which reverses anaphylaxis).

- Immunotherapy: This is a long-term treatment that involves gradually exposing the immune system to increasing doses of allergens over several months or years. This can help desensitize the immune system and reduce its response to allergens. Immunotherapy can be given as injections under the skin (subcutaneous immunotherapy) or as tablets under the tongue (sublingual immunotherapy).

- Lifestyle changes: Some lifestyle changes can help improve the overall health and well-being of people with allergies. These include eating a balanced diet rich in fruits and vegetables, drinking plenty of fluids, exercising regularly, managing stress, getting enough sleep and quitting smoking.

Allergy is a common but manageable condition that can affect the quality of life of many people. By knowing the causes, symptoms, diagnosis and treatment of allergy, you can take steps to control your condition and prevent complications. If you have any questions or concerns about your allergies, talk to your doctor for advice and guidance.