Allergies occur when your immune system reacts to a foreign substance—such as pollen, bee venom or pet dander—that doesn’t cause a reaction in most people.
Your immune system produces substances known as antibodies. Some antibodies protect you from unwanted invaders that could make you sick or cause infection.
The severity of allergies varies from person to person and can range from minor irritation to anaphylaxis—a potentially life-threatening emergency.
Allergy symptoms depend on the substance involved and can involve the airways, sinuses and nasal passages, skin, and digestive system. Allergic reactions can range from mild to severe. In some severe cases, allergies can trigger a life-threatening reaction known as anaphylaxis.
- Itching of the nose, eyes or roof of the mouth
- Runny, stuffy nose
- Watery, red or swollen eyes (conjunctivitis)
A food allergy may cause:
- Tingling mouth
- Swelling of the lips, tongue, face or throat
An insect sting allergy may cause:
- A large area of swelling (edema) at the sting site
- Itching or hives all over your body
- Cough, chest tightness, wheezing or shortness of breath
A drug allergy may cause:
- Itchy skin
- Facial swelling
Atopic dermatitis, an allergic skin condition also called eczema, may cause skin to:
- Flake or peel
Some types of allergies, including allergies to foods and insect stings, have the potential to trigger a severe reaction known as anaphylaxis. A life-threatening medical emergency, this reaction can cause you to go into shock. Signs and symptoms of anaphylaxis include:
- Loss of consciousness
- A drop in blood pressure
- Severe shortness of breath
- Skin rash
- A rapid, weak pulse
- Nausea and vomiting
Allergy treatments include:
- Allergen avoidance. Your doctor will help you take steps to identify and avoid your allergy triggers. This is generally the most important step in preventing allergic reactions and reducing symptoms.
- Medications to reduce symptoms. Depending on your allergy, allergy medications can help reduce your immune system reaction and ease symptoms. Medications can include over-the-counter or prescription medications in the form of oral medications, nasal sprays or eyedrops.
- Immunotherapy. For severe allergies or allergies not completely relieved by other treatment, your doctor may recommend allergen immunotherapy. This treatment involves a series of injections of purified allergen extracts, usually given over a period of a few years.
Another form of immunotherapy is a tablet that’s placed under the tongue (sublingual) until it dissolves. Sublingual drugs are used to treat some pollen allergies.
- Emergency epinephrine. If you have a severe allergy, your doctor may give you an emergency epinephrine shot to carry with you at all times. Given for severe allergic reactions, an epinephrine shot (EpiPen, Auvi-Q, others) can reduce symptoms until you get emergency treatment.