What Are Allergies?

Allergies occur when the immune system reacts to a normally harmless substance—such as pollen, dust, or mold—that does not affect most people.

When someone with allergies comes into contact with these substances, known as allergens, their immune system overreacts, producing antibodies called immunoglobulin E (IgE) to attack the allergen. These antibodies travel to cells throughout the body, releasing histamine and other chemicals that cause an allergic reaction.

This article explores different types of allergies, their symptoms, and ways to manage them.

A woman sneezing and blowing her nose

Inside Creative House / Getty Images

Allergy Symptoms

Symptoms of an allergic reaction can vary from person to person. Common symptoms include:

More severe symptoms that warrant a visit to a healthcare provider for treatment include:

  • Swelling in the mouth and throat
  • Tightness in the chest
  • Difficulty breathing
  • Feeling faint or light-headed
  • Throat closing
  • Nausea, vomiting, or diarrhea

Is It Allergies or Something Else?

Allergy symptoms often overlap with viral illnesses, such as the common cold, the flu (influenza), or the coronavirus (COVID-19). If you have a cough and headache, accompanied by body aches and fever, visit a healthcare provider to rule out a virus. Colds tend to be milder and do not cause fever or body aches. They typically resolve on their own within a few days.

What Causes Allergies?

Allergies occur when the immune system reacts to a usually harmless allergen. When exposed to the allergen, the immune system tries to fight it off, similar to how it would do with a germ or virus.

While it is not well understood why allergies occur, genetics can play a role. Reactions to specific allergens, such as peanuts, are not passed down. However, parents with allergies are more likely to have kids with allergies.

Do Allergies Cause Asthma in Kids?

Children who suffer from allergies are at a greater risk of developing asthma. Allergies can worsen asthma symptoms in children with the condition. Managing allergy symptoms can play an important role in preventing asthma attacks.

Common Allergens

Common allergens include:

Seasonal Allergies

Seasonal allergies, also known as seasonal allergic rhinitis or hay fever, occur during the spring, summer, or fall when trees, weeds, and grasses pollinate.

Spring allergies are caused by tree pollen and typically occur from around February to early summer. However, over two-thirds of people with spring allergies experience symptoms yearly.

Late-spring and early-summer allergies are typically caused by grass pollen, which may cause symptoms throughout the year, especially in warm or tropical climates, where pollen counts stay high.

Late-summer and fall allergies are generally caused by weed pollen, especially ragweed pollen, which reaches peak levels in many areas of the United States in early to mid-September.

Mold spores can cause allergies in the spring, summer, and fall. They can cause allergies throughout the year for people who live in buildings with high moisture levels.

Allergy Testing to Diagnose Allergies

An allergist can help determine the specific allergen causing your symptoms by reviewing your medical history and performing skin testing or a specific IgE blood test.

During skin testing (a puncture or scratch test), a healthcare provider places a small amount of the allergen on the skin and then makes a slight prick or scratch. If the skin reacts, the person may have an allergy.

Intradermal testing is often used for allergies to penicillin and insect stings. It involves injecting a small amount of the allergen under the skin using a needle.

A specific IgE blood test measures the amount of IgE your body produces in response to a single allergen.

Allergy Medicine and Treatment

The best way to manage an allergy is to reduce exposure or avoid the allergens completely. However, this is not always possible. Medications and treatments can help.


A healthcare provider may recommend prescription medications if over-the-counter (OTC) medications do not relieve your allergies. These include:

  • Oral corticosteroids: Reduces inflammation and stops severe allergic reactions
  • Antihistamines and decongestants: Mostly of equal strength, with the exception of some stronger, prescription oral antihistamines, such as Clarinex(desloratadine)
  • Leukotriene modifiers: Blocks symptom-causing chemicals (leukotrienes); Singulair (montelukast sodium) is approved for treating allergies
  • Mast cell stabilizers: Prevents your body from releasing histamine and are most effective when used before allergen exposure.

Home Treatment

In many cases, allergies can be managed at home using the following at-home treatments.

  • Corticosteroid creams and nasal sprays: Nasal corticosteroid sprays, such as Flonase (fluticasone), work by reducing swelling and inflammation. They are considered the best treatment for nasal allergies. OTC corticosteroid creams and ointments are also available to clear rashes and relieve itchiness.
  • Antihistamines: Antihistamines, such as Benadryl (diphenhydramine), relieve allergy symptoms by blocking the effects of histamine. They are available OTC in pills, chewable tablets, eye drops, and nose sprays.
  • Decongestants: Decongestants narrow blood vessels in the nose, reducing swollen tissue. This helps you breathe more easily. Examples include Sudafed (pseudoephedrine) and Afrin (oxymetazoline) nasal spray.

Many also find relief from allergies using nasal irrigation devices, such as neti pots and bulb syringes. These devices can effectively flush the nasal passages and filter out allergens

It's important to avoid using tap water when flushing the nose. Tap water is not considered safe to use as a nasal rinse. It isn't adequately treated or filtered and can contain bacteria and protozoa. Always use sterile or distilled water when using nasal irrigation devices.

Other home remedies for allergies include:


Your healthcare provider may recommend immunotherapy if you have allergies triggered by environmental factors, such as pollen, dust mites, bee venom, or pet dander.

Immunotherapy exposes you to a small amount of the allergen over time, allowing your immune system to become desensitized or develop a tolerance to the allergen.

The two most common types of immunotherapy are allergy shots and sublingual (under the tongue) immunotherapy (SLIT).

What Is Anaphylaxis?

Anaphylaxis is a severe, sudden life-threatening allergic reaction that involves the whole body. Symptoms often occur within 30 minutes of exposure to the allergen. However, in some cases, symptoms can take more than an hour to develop.

Symptoms of anaphylaxis include:

  • Confusion
  • Difficulty breathing
  • Rapid heart rate
  • Slurred speech
  • Dizziness
  • Anxiety
  • Facial swelling
  • Heart palpitations
  • Abdominal pain or cramping
  • Nausea, vomiting, or diarrhea
  • Hives and itching

If left untreated, the condition can result in death. Anaphylaxis is treated with epinephrine (adrenaline). Epinephrine autoinjectors (EpiPens) contain a prescribed single dose of medication injected into the thigh.

How to Prevent Allergies

The best way to prevent allergies is to avoid exposure to the allergen. Depending on your allergy trigger, this may mean:

  • Taking medications as recommended by a healthcare provider or allergist
  • Avoiding certain food allergens
  • Exercising indoors during peak allergy season
  • Regularly vacuuming carpets and dusting
  • Installing high-efficiency particulate air (HEPA) air filters in your home and cleaning vents often

Living With Allergies

Coping with allergies can be stressful. However, identifying effective prevention and treatment methods can make symptoms more bearable and improve your quality of life.

In addition to working closely with your allergist and implementing the prevention and treatment strategies discussed, you may also find it helpful to join a support group to encourage you during tough times.

22 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Allergy Asthma and Immunology. Allergies overview.

  2. Asthma and Allergy Foundation of America. Allergy symptoms.

  3. National Institutes of Health. Is it flu, COVID-19, allergies, or a cold?

  4. American Collage of Allergy, Asthma, & Immunology. Allergies 101.

  5. The Nemours Foundation. Do allergies cause asthma?

  6. Asthma and Allergy Foundation of America. Allergies.

  7. American College of Allergy, Asthma, and Immunology. Seasonal allergies.

  8. MedlinePlus Magazine. What triggers seasonal allergies?

  9. American College of Allergy, Asthma, and Immunology. Testing and diagnosis.

  10. MedlinePlus. Allergy blood test.

  11. Asthma and Allergy Foundation of America. Allergy treatments.

  12. MedlinePlus. Desloratadine.

  13. Kaur G, Dhingra R, Singh M, Kaur M. Montelukast: a better alternative than antihistaminics in allergic rhinitisInternational Journal of Otorhinolaryngology and Head and Neck Surgery. 2017(3)2. doi:10.18203/issn.2454-5929.ijohns20171185

  14. MedlinePlus. Antihistamines for allergies.

  15. U.S. Food and Drug Administration. Is rinsing your sinuses with neti pots safe?

  16. Tian HQ, Cheng L. The role of vitamin D in allergic rhinitisAsia Pac Allergy. 2017;7(2):65-73. doi:10.5415/apallergy.2017.7.2.65

  17. Seidman MD, Gurgel RK, Lin SY, et al. Clinical practice guideline: allergic rhinitisOtolaryngol Head Neck Surg. 2015;152(1_suppl):S1-S43. doi:10.1177/0194599814561600

  18. Bakhshaee M, Mohammad Pour AH, Esmaeili M, et al. Efficacy of supportive therapy of allergic rhinitis by stinging nettle (Urtica dioica) root extract: a randomized, double-blind, placebo-controlled, clinical trialIran J Pharm Res. 2017;16(Suppl):112‐118.

  19. National Center for Complementary and Integrative Health. Butterbur.

  20. American College of Asthma, Allergy, and Immunology. Allergy immunotherapy.

  21. American Academy of Allergy, Asthma & Immunology. Anaphylaxis.

  22. Johns Hopkins. Anaphylaxis.

By Lindsey DeSoto, RD, LD
Lindsey Desoto is a registered dietitian with experience working with clients to improve their diet for health-related reasons. She enjoys staying up to date on the latest research and translating nutrition science into practical eating advice to help others live healthier lives.