What Is Allergies

Allergies occur when the immune system overreacts to typically harmless foreign particles (allergens) in the body. The symptoms that are a result of the immune system’s overreaction range from mild discomfort to life-threatening emergencies depending on the trigger and the allergic person’s individual response.

According the National Institute of Allergy and Infectious Diseases, allergies are widespread in all age groups in the United States. The Centers for Disease Control reports that as of the last census, 2010, allergies are the 6th leading cause of chronic illness in the U.S. with an annual cost in excess of $18 billion. More than 50 million Americans suffer from allergies each year.

The most common types of allergies are:

Food allergies. The list of food allergens as reported by Food Allergy Research and Education Incorporated, a non-profit organization, includes:

  • Peanuts (legume)
  • Tree nuts (walnuts, almonds, hazelnuts, cashews, pistachios, and Brazil nuts)
  • Milk (not to be confused with lactose intolerance, which causes discomfort but is never life-threatening and does not involve an abnormal immune response)
  • Eggs
  • Wheat (not to be confused with gluten intolerance or Celiac disease, which cause discomfort but are never life-threatening and don’t involve abnormal immune responses)
  • Soy
  • Fish
  • Shellfish

The American Academy of Allergy Asthma & Immunology also lists:

  • Strawberries
  • Cherries
  • Grapes

Environmental allergies. Some of these are referred to as seasonal allergies because they are triggered by plant pollen at various times of the year. Others can occur year round. The National Institute of Environmental Health Sciences lists the following as common environmental allergens:

  • Pollen (ragweed, grass, tree)
  • Pets and other animals
  • Mold (also mildew, both caused by a fungi)
  • Dust mites
  • Cockroaches
  • Cigarette smoke

Insect allergies. The American College of Allergy, Asthma & Immunology lists the following stinging insects as potential allergens:

  • Bees
  • Wasps
  • Yellow jackets (a type of wasp)
  • Hornets

Allergies to pets and other animals. Many people are allergic to the dander or saliva of household pets. Cat and dog dander are among the most common pet allergies, though smaller furry animals, such as hamsters, guinea pigs, and other rodents, can also serve as allergens.

Contact allergies. The Asthma and Allergy Foundation of America lists the following substances and materials as potential allergens:

  • Dye for your hair, clothing, leather, furs
  • Nail care products, cosmetics, sunscreen
  • Fragrances, perfumes
  • Rubber compounds, including latex
  • Topical medications
  • Poison ivy, other plants
  • Detergents, cleaning products
  • Metals, especially nickel

Allergies to medications. The American Academy of Allergy Asthma & Immunology lists the following as common medication allergens:

  • Antibiotics, such as penicillin
  • Aspirin and non-steroidal anti-inflammatory medications, such as ibuprofen
  • Anticonvulsants
  • Monoclonal antibody therapy
  • Chemotherapy

What Causes Allergies

If your immune system perceives a substance as a threat to your health, a team of cells, specifically IgE type 1 hypersensitive immune response cells—releases mast cells into the system to create antibodies that remain ready to attack every time you encounter the substance. The antibodies release a chemical called histamine, which helps activate the body’s defense mechanisms against potentially harmful foreign substances – fever, sneezing, coughing, etc. In the case of allergies, this immune response is triggered by a substance that is not usually harmful (i.e. pollen, dust, animal dander). The body releases histamine to fight against the foreign substance and in turn causes allergy symptoms – runny nose, sneezing, watery eyes, wheezing, etc.

Medical experts are not sure of the exact cause of the abnormal immune response, but they have identified several risk factors that may influence the development of allergies.

Risk Factors For Allergies

The following factors may put you at increased risk of developing allergies:

  • Heredity. Many people inherit allergies such as hay fever, food allergies, and contact dermatitis, among others. The allergies may remain latent for years until you come in contact with a potent trigger such as an unusually high pollen count. Once you have an adult onset allergy, the reaction almost never goes away because the antibodies “remember” the intruder and attack every time you encounter the substance, even in small amounts.
  • High levels of interleukin-4 (IL-4). Researchers have linked high levels of this protein that promotes the development of mast cells, T-cells, and activated B-cells in the immune system with a proclivity to having allergies. Studies have shown that African-Americans have particularly high levels of Il-4.
  • Location. People who live in urban areas are more likely to have allergies than people who live in rural areas. Even so, researchers have not been able to link outdoor pollutants such as sulfur dioxide, particulate matter, and ozone to allergies. Tobacco smoke, on the other hand, has been identified as a powerful allergen.
  • Excessive Hygiene. The “hygiene hypothesis” suggests that Western civilization’s obsession with cleanliness, including the use of antibacterial products, has contributed to a rise in the number of people with allergies. Among other studies, a report released on October 4th 2012 by the International Scientific Forum on Home Hygiene noted that “microbial exposure” is important. The theory is that exposure to germs and potential allergy triggers, especially during childhood, “teaches” the immune system to differentiate between friend and foe so that “mistakes” leading to allergies won’t happen. This could be the reason that children who grow up with pets are less likely to have allergies to animals. Maybe the old adage about needing to eat a peck of dirt before we die isn’t so far off after all!

Diagnosing Allergies

Your doctor will use one or a combination of the following diagnostic techniques to determine whether or not you have allergies:

  • Medical History. Since allergies and other similar conditions can run in families, your doctor will ask about your medical history and about the medical history of your family.
  • Symptoms. Your doctor will ask you about the symptoms you have been experiencing, as well as when and where you experienced them. If you have trouble keeping track of your symptoms, keep a journal that documents your allergic reactions and potential triggers.
  • Physical Exam. This will help to rule out any other potential causes of the allergic symptoms as well as bring to the doctor’s attention any symptoms which may not have been reported.
  • Skin test. After pricking your skin, the doctor – preferably a trained allergist — will expose the open spot on your skin to your suspected allergen. If a hive forms, you are most likely allergic to the allergen.
  • Blood test. The RAST (radioallergosorbent) test, done with a sample of your blood at a laboratory, measures the amount of immunoglobulin E (IgE) antibodies in your blood. When IgE antibodies bind to antigens, they launch an immune reaction against the antigen, causing symptoms of an allergic reaction. IgE antibodies are highly specific, meaning that there is a specific antibody for each type of antigen (allergen). During a RAST test, blood samples are exposed to allergens to see if allergens bind to antibodies or not. If the allergen does not bind, that means that there is no antigen for it present, and an allergic reaction cannot occur.

Symptoms of Allergies

Different types of allergens can cause different symptoms. Though not all people with allergies will have the same reactions, here are some common symptoms of allergic reactions:

Food allergies

  • A tingling or sometimes stinging sensation in your mouth
  • Swelling of your lips, tongue, and/or face
  • Swelling of your throat so that you have difficulty swallowing
  • Hives
  • Anaphylaxis – a life-threatening systemic reaction that happens very quickly – usually within minutes but sometimes after about an hour. Many allergens can be culprits, including peanuts, bee stings, and penicillin. Immediate medical attention is required. Symptoms may include:
    • Feeling dizzy
    • Fainting, loss of consciousness
    • Flushing of the skin
    • Pale skin
    • A sensation of overall heat or warmth
    • A “lump in your throat”
    • Wheezing
    • Difficulty breathing
    • A weak and fast pulse
    • Nausea and vomiting
    • Diarrhea

Environmental allergies

  • Coughing, sneezing, stuffy nose. Combined, these symptoms make the most common form of environmental allergy known as hay fever, or sinusitis (allergic rhinitis).
  • Watery, itchy eyes
  • Wheezing, feeling short of breath

Insect allergies

  • Anaphylaxis as a result of a sting. (See above under Food Allergies.)
  • Larger than expected swelling at the site of the sting.
  • Hives on various places not near the sting site.
  • Itching, usually on the entire body
  • Coughing

Allergies to pets

  • Itchy, watery eyes
  • Red, swollen face
  • Sneezing and a runny, stuffy nose
  • Coughing and wheezing

Contact allergies

  • Rashes
  • Redness where the allergen touched your skin
  • A chronic condition called eczema
  • Flaking and peeling skin

Allergies to medications

  • Hives
  • Rashes
  • Itchy skin
  • Swelling of the face
  • Wheezing, trouble breathing
  • Anaphylaxis (see above under food allergies)


Food allergies. According to an article published in the journal Asthma, Allergy & Clinical Immunology, the prognosis for food allergies “is complex and dependent on the particular food”. The authors conclude that and increasing number of children are outgrowing egg and milk allergies as they reach adolescence but that allergies to peanuts, tree nuts, fish, and shellfish are more persistent, and “lifelong in most cases”.

Environmental allergies. Many children outgrow environmental allergies, especially allergic rhinitis (hay fever), but the condition sometimes comes back in adulthood. People who develop environmental allergies after the age of about 20 tend to have the allergies in middle age and often well beyond.

Insect allergies. Allergic reactions to stinging insects are almost always lifelong. People who are affected need to carry epinephrine injectors such as EpiPens at all times for use as an antidote to life-threatening anaphylaxis. (See the section on Causes as well as the section on Treatments and Medications.)

Allergies to pets. Some children do outgrow allergies to animals. Also, some adults find that their symptoms lessen or disappear over time. However in most, cases pet allergies are persistent and require lifelong management. (See the section on Living With Allergies.)

Contact allergies. Reactions to substances such as cosmetics and cleaning agents may fluctuate over time and eventually disappear altogether – though not in all cases. However, an allergy to latex appears to be lifelong and can be life-threatening. Be sure to tell your doctor about your latex allergy, especially if you are scheduled for surgery. You can be assigned to a latex-free operating room. In addition, always carry an EpiPen. (See above under Insect Allergies.)

Allergies to medications. These are almost always lifelong and can be life-threatening. Tell your doctor if you have an allergy to an antibiotic such as penicillin. You may also be allergic to other medications in the same class of drugs. Also let your doctor know if you are allergic to iodine, which is used in dyes for some screening tests.

Living With Allergies





  • Read nutrition labels. You’ll find information such as whether additives contain milk protein or byproducts of wheat, or whether a food was produced in a facility that processes nuts.
  • Have two sets of cookware and eating utensils if there are household members both with and without allergies. Keep the items reserved for the allergic household member in a separate place and always wash all dishes and utensils in hot, soapy water.
  • Be pro-active in restaurants. Consider carrying a “chef card” listing the ingredients to which you are allergic. You can customize this template on the Food Allergy and Anaphylaxis Network website, [NOTE: hyperlink ‘website’ to //]
  • Wear a medical ID bracelet or necklace. Make sure it lists relevant information about your food allergy.
  • Carry your medication with you at all times, preferably two doses. Emergency epinephrine injector as well as antihistamines if you take those.


   Indoor allergies

  • Encase bedding in plastic or dust-mite repelling fabric covers. This will help to keep dust particles and dust mites (both common allergens) from settling into your mattress.
  • Wash bedding weekly and tumble dry on high. Washing will keep bedding dirt and dust-free, and the high heat of the dryer will help to kill off any dust mites.
  • Avoid down pillows or comforters. Dust mites and dander have a tendency to collect in down feathers.
  • Opt for hardwood or laminate floors rather than carpeting and rugs. They will be easier to keep clean and will allow less dust to settle in them.
  • Use a humidifier in the winter and dehumidifier to maintain ideal humidity levels within your home. Extremely dry conditions can inflame your sinuses, and conditions that are too humid provide an ideal environment for dust mites and mold spores. Be sure to regularly clean the filters of both to avoid mold and dust accumulation.
  • Vacuum once a week using a HEPA filter or a 2-ply bag. This will help to prevent dirt and dust particles from escaping into the air.
  • Use a damp mop or rag rather than a dry cloth when you dust. This will trap potentially irritating dust mites rather than stir them into the air.
  • Clean often and keep your home free of mold and mildew.
  • Don’t smoke! Smoke particles are left in the air and on surfaces in your home even after you smoke, and are common allergens. Smoking also damages your natural mucous membranes which serve a large defensive purpose in the body.

  Outdoor allergies

  • When you’re inside, keep windows closed and use air conditioning to limit the amount of pollen spores entering your home. Make sure you clean your air conditioning filter often in order to reduce the amount of mold and dust.
  • Stay indoors if the pollen count is high.
  • After you’ve been outside, shower, wash your hair, and put on clean clothes to stop the spores from outside from spreading around your home.
  • Don’t hang clothes to dry on a line outside where they can collect pollen.




  • Don’t go barefoot. Stinging insects can hide in the grass and dirt.
  • Wear long pants or skirts and long sleeves.
  • Avoid using perfume and other scented products that can attract insects.
  • Use insect repellant such as DEET, which has been shown to be safe.



  • Create an allergy free area in your home, such as the allergic person’s bedroom, and don’t let the pet go in there. Keep the door closed for the majority of the time, provided there is ample ventilation through a heating system or open window. This will help keep the dander out of the room.
        • Use HEPA (High-efficiency particulate air) cleaners in the entire house. Make sure to properly maintain the system to keep mold spores and animal dander from circulating in the home.
        • Avoid dander catchers such as cloth curtains and blinds and carpeted floors. Dander is dead skin cells that have been shed. That’s what you’re allergic to – not the fur!
        • Bathe your pet once a week to keep dander to a minimum.




  • Don’t scratch your rash. This can cause an infection or scarring.
  • Continue to bathe with soap and water daily.
  • Put a gentle compress on your rash. Soak a washcloth briefly in cool water mixed with a couple of tablespoons of baking soda. Wring out the cloth and then place it on the rash.




  • Tell any new doctor or specialist about your allergies. Allergies to medications can have serious and potentially lethal side effects. Don’t hesitate to bring up any potential or established allergies to medications at appointments, even if they seem to be unrelated to the cause.
  • Carry a medical information card with you at all times in case you are ever injured or ill and can’t explain your allergies to first responders and hospital personnel.


Since allergies are so common and there are an almost infinite number of possible allergens, allergies are not screened for in primary care practices. If you are experiencing any of the symptoms associated with allergies, schedule an appointment with your doctor. He or she will be able to conduct the appropriate diagnostic tests and/or refer you to an allergist or allergy specialist for further testing.


The root causes of allergies are unknown, so prevention of allergies is not typically possible. There is research into prevention of certain food allergies via introduction of the allergen in minute amounts, under the guidance of an allergist. This new form of treatment is reserved for those with a family history of life-threatening allergies, like to peanuts. You can, however, avoid triggering allergens and seek treatment to lessen the severity of your allergy attacks.

Medication And Treatment

The most effective way to treat allergies is to avoid the allergen. Since this can sometimes be difficult or impossible, other treatments are available. Treatments may include:


  • Antihistamines-stop the interaction between histmamine and the receptors; block the action of histmaine; usually taken as pills or syrup
  • Decongestants-decrease congestion by constricting blood vessels, taken as pills or as a nasal spray; use of the nasal spray may lead to rebound congestion
  • Mast cell inhibitors-nasal sprays that interfere with the chemical reactions leading to histamine release
  • Topical corticosteroids-nasal sprays that decrease swelling in the nasal passages

Immunotherapy (Allergy Shots) and Sublingual Therapy

With immunotherapy, very small amounts of allergens are injected over weeks, months, or even years. The goal is to make your body’s immune system less sensitive to those allergens.

There’s another, similar type of treatment called sublingual immunotherapy. It involves placing small amounts of allergens under the tongue. This treatment is more popular in Europe. While it has shown to reduce symptoms in some studies, more research is needed.

If you are diagnosed with allergic rhinitis, follow your doctor’s instructions.

Complementary and Alternative Treatment

If you choose to use any herbs or supplements, remember to let your doctor and your pharmacist know. Prescriptions drugs and your alternative treatments may have adverse interactions with each other. Also, a recent study found that many herbal supplements contain fillers and some have none of the herbs and other ingredients lists on the labels. The Food and Drug Administration does not regulate herbal and other “natural” supplements.

The National Center for Complementary and Alternative Medicine (NCCAM) recommends the following alternative treatments for allergy symptoms:

  • Butterbur (petasites, purple butterbur) is a shrub that grows in Europe and parts of Asia and North America. There are several patented standardized extract forms, such as Petadolex. An NCCAM-funded literature review reports that in a clinical trial of 125 participants, butterbur was just as effective as a commonly used oral antihistamine for allergy symptoms such as itchy eyes. There is some evidence that butterbur extract can decrease the symptoms associated with nasal allergies, but there is not enough evidence to show efficacy and safety of butterbur for allergic skin reactions. In a study published in the British Medical Journal, Swiss researchers showed that butterbur four times daily was as effective as an antihistamine medication in controlling hay fever. The raw, unprocessed butterbur plant can cause liver damage, but several studies have reported that processed butterbur products that are free of pyrrolizidine alkaloids (Pas) are safe and well tolerated, for up to 12 to 16 weeks, according NCCAM. The safety of longer-term use has not been established. Butterbur can cause belching, headache, itchy eyes, gastrointestinal issues, asthma, fatigue, and drowsiness. Also, using Butterbur as an allergy treatment may backfire if you’re allergic reactions to plants such as ragweed, a close relative to butterbur.
  • Milk Thistle (Mary thistle, holy thistle) is a flowering herb native to the Mediterranean region. Milk thistle is also sometimes called silymarin, which is actually a mixture of the herb’s active components, including silybinin (also called silibinin or silybin). Some sources, including the Mayo Clinic, claim that this herb may lessen the symptoms of allergic rhinitis (hay fever), but NCCAM does not mention using the herb for this purpose.
  • Neti Pots. A neti pot is a small vessel with a spout, which you fill with a mixture of warm water and salt (filtered water is best here), to wash the inside of your nose and nasal passages (nasal lavage). How does it work? You pour the water into one nostril and it comes out of the other. A safe, easy, and cheap alternative to commercial nasal sprays and other medications. An effective treatment on its own, but may work best in combination with other allergy treatments.
  • Acupuncture treatments may be able to calm the parts of the immune system that are overactive, reducing the severity of allergy symptoms. While there is widespread anecdotal evidence about the effectiveness of acupuncture as a treatment for allergies, there are a limited number of studies to back it up.
  • Homeopathic remedies. Some believe that homeopathic remedies, which contain diluted amounts of plant extracts, may be effective in treating allergies. The following substances are endorsed by many homeopathic practitioners, though little research data is available to support their claims:
    • Allium Cepa for itchy, watery eyes
    • Nux Vomica for itchy nose and throat
    • Kali Bichromium for sinus irritation, sneezing, runny nose



Care Guide

Though there is no cure for allergies, there are things that you can do to help manage your symptoms:

  • Identify your triggers and stay away from them. Keep a diary so you’ll have a record of what it is that triggers your symptoms. Avoid what you know will cause your symptoms when possible.
  • Notify others about your allergies when necessary. This is especially relevant to food allergy sufferers when dining out at restaurants, and to those with pet/animal dander allergies when visiting friends or family. Don’t feel guilty about asking for special accommodations – your health depends on it!
  • Think ahead. Read the pollen count ahead of time along with the weather forecast. If you know you are going to encounter an allergen, take medicine before you feel symptoms coming on to have the most control over your allergy symptoms.
  • Stay indoors when the pollen count is high if you’re a spring seasonal allergy sufferer. Be careful of open windows and house guests coming from the outside, which can be sources of pollen.
  • Use an air filter to help remove dust, pollen, and mold spores from the air in your home.
  • Skip flowery perfumes and use insect repellant to make yourself less desirable to insects if you have insect sting allergies.
  • Spend time outdoors each day if you are allergic to indoor allergens (dust, mold, pet dander, etc.). The fresh air may help to clear up your symptoms. Beware of urban smog and high pollen counts outdoors, which can both worsen your symptoms.

When To Contact A Doctor

If you have severe allergies and risk going into anaphylactic shock during an attack, call emergency services (911) if you experience any of the following symptoms of anaphylaxis:

  • Abnormal breathing
  • Skin Redness
  • Hives
  • Wheezing
  • Cough
  • Difficulty swallowing
  • Swelling of the face, eyes, or tongue
  • Abdominal pain
  • Diarrhea
  • Nasal congestion
  • Slurred speech
  • Unconsciousness

You should also call your doctor if:

  • The medication you’ve been prescribed is not working
  • Your symptoms seem to be getting worse instead of better
  • You are having trouble breathing
  • Your heart is racing or beating irregularly
  • A rash such as one from poison ivy is spreading near your eyes
  • You are vomiting and/or have diarrhea and might be getting dehydrated. (Please note, dehydration is serious and may require a hospital stay.)
  • You suspect for any reason at all that your symptoms might be cause for concern. Each person’s allergic reactions are different and symptoms can vary even for the same person. Don’t be embarrassed if you go for a check-up and your worry turns out to be a false alarm. Better safe than sorry –and your doctor will agree!

Questions For A Doctor

Before your visit to your Primary Care Physician for an initial exam and then again after you schedule an appointment with an allergist, write down all your questions and concerns. Bring them with you as a printout or on your tablet. Also, consider asking a friend or family member to come along and help you get all your questions answered in case you start feeling flustered or embarrassed and forget a key issue you wanted to discuss.

Here are some questions you may want to ask your doctor:

  • Could my allergy be life threatening? If so, are there any steps I can take to protect myself in an emergency?
  • Is exercising safe for me? Are there any exercises I should or shouldn’t be doing?
  • Even if I don’t have food allergies, are there dietary restrictions or recommendations that you have for me?
  • What treatments do you recommend for me?
  • Are there possible side effects to the treatments?
  • Are there any alternative treatments that are safe and effective for my condition?
  • If you prescribe medication, how long will I need to take it?
  • Is the medication in the formulary of my insurance plan?
  • How much will the medication and treatments cost?
  • Is there any chance I will need surgery?
  • Could my allergy just go away on its own?
  • Are there any lifestyle changes I should make to help control my allergy?
  • Could my allergy make me more susceptible to any diseases or conditions?
  • Is there any way to prevent getting more allergies as time goes by?


May is National Asthma and Allergy Month, and May 11th to 17th is Food Allergy Awareness Week.

For more information on allergies and resources for allergy sufferers, visit:

For the latest research and information on the asthmatic component of allergies, visit:

For the latest research on food allergies and for resources for food allergy sufferers, visit:

For more information on the role of environmental factors in allergies, visit:

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