Allergy Guide: Prevention and Treatment Options

An allergy is an exaggerated immune response or reaction to substances that are generally not considered harmful. You can be allergic to pollen (see hay fever), dust, pet dander, mold, food and certain medications. Allergic reactions can also be caused by insect bites, jewelry, cosmetics, and almost any substance that contacts the body. Some people have allergic-type reactions to hot or cold temperatures, sunlight, or other physical stimuli, such as friction (rubbing or vigorously stroking the skin).

Allergies are relatively common, occuring in about 20 out of every 100 people (20% of the population). Both hereditary (family history) and environmental factors have been found to play a role in their development.

Some medical disorders and complications can be associated with allergies. These include:

  • eczema
  • hives
  • asthma
  • respiratory tract infections
  • life-threatening anaphylaxis.

Most allergies cannot be cured, but not all people have severe symptoms. However, treatment for allergies can dramatically improve a patient's quality of life.

What causes an allergy?

An allergy is caused by an oversensitive immune system, which leads to an improper immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. When an allergic reaction occurs, it is a result of the immune system reacting to substances (allergens) that are generally harmless and in most people do not cause an immune response.

In a person with allergies, the first exposure to the allergen triggers the immune system to recognize the substance. Any exposure after that will usually result in symptoms. When an allergen enters the body of a person with a sensitized immune system, histamine and other chemicals are released by certain cells. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms. These can vary in severity from person to person. Most people have symptoms that cause discomfort without being life-threatening.

A few people have life-threatening reactions (called anaphylaxis), which is a medical emergency.

Who is at risk of an allergy?

People with a greater chance of having an allergy may have these risk factors:

  • Family history of asthma or allergies (such as hay fever, hives, or eczema)
  • Younger age
  • Diagnosed with asthma


Allergy symptoms vary depending on what is causing the reaction and the part of the body where the reaction occurs. They can range from mild, annoying effects to severe, possibly fatal reactions.

  • Inhaled allergens such as pollen (hay fever) or mold cause allergic rhinitis with a runny nose, nasal congestion, seezing, an itchy nose and throat, mucus production, watery eyes, cough, or wheezing.
  • A food allergen like nuts of fish can cause tingling of the mouth, swelling in the throat, shortness of breath, hives, and a severe, life-threatening reaction (anaphylaxis) with shortness of breath or wheezing. Stomach reactions like cramps, vomiting, or diarrhea may be present.
  • Insect bite allergies, such as with bees or ants, can cause swelling at the site where the bite occurred, itching, hives, wheezing, cough, and shortness of breath, and anaphylaxis.
  • Plant allergies to certain grasses or trees can often cause red, watery eyes, skin rash, blisters, itching, and anaphylaxis.
  • Allergic drug reactions, like with penicillin, can cause shortness of breath, wheezing, swelling, rash, itching, fever, hives, and anaphylaxis.

Symptoms of anaphylaxis include:

  • fainting
  • low blood pressure
  • shortness of breath
  • rash
  • dizziness
  • fast heart rate
  • nausea and vomiting


The history of your symptoms is important in diagnosing all allergies, including whether the symptoms vary according to time of day, season, exposure to pets and other potential allergens, and diet changes. Severe reactions often develop very quickly after exposure, such as eating nuts or getting stung by an insect.

Allergy testing may be required to determine if your symptoms are an actual allergy or caused by other problems. For example, eating contaminated food (food poisoning) may cause symptoms that resemble food allergies. Some medications (such as aspirin, ampicillin, and others) can produce non-allergic reactions, including rashes, that resemble drug allergies but are not true allergies.

Tests that may reveal the specific allergens include:

  • Skin testing -- the most common method of allergy testing. This may include intradermal, scratch, patch, or other tests. A doctor or nurse will prick your skin with a small amount of the allergen, and if you are allergic, you'll develop a small bump (hive) at the test site on your skin. Skin testing may even be an option for young children and infants, depending on the circumstances.
  • Blood test -- RAST (radioallergosorbent) blood testing measures the levels of allergy antibody, IgE, produced when your blood is mixed with a series of allergens and sent to a laboratory. If you are allergic to a substance, the IgE levels may increase in the blood sample. The blood test may be used if you have existing skin problems like eczema, if you're on medications that are long-acting or that you cannot stop taking, if you have a history of anaphylaxis, or if you prefer not to have a skin test.
  • "Use" or "elimination" tests -- suspected items are eliminated and/or introduced while the person is observed for response to the substance. This is often used to check for food or medication allergies.

Other tests that may reveal allergies include:

  • Antibody/immunoglobulin (particularly IgE) levels -- when these are elevated, it indicates a "primed" immune system.
  • CBC (complete blood count) -- may reveal an increase in eosinophils (a type of white blood cell).
  • Complement levels may be abnormal. The complement system aids the immune system in helping to fight off infection or disease.

Allergy Treatments

The best "treatment" is to avoid what causes your allergies. However, practically it may be impossible to completely avoid everything you are allergic to, especially if you have hay fever. You can often take steps to reduce your exposure, which is especially important for food and drug allergies.

The goal when treating allergies is to reduce the symptoms caused by inflammation of the affected tissues. The most appropriate medication depends on the type and severity of symptoms. Specific illnesses that are caused by allergies (such as asthma, hay fever, and eczema) may require other treatments, as well.

Common Allergy Medications

Nasal corticosteroid sprays (Table 1) are safe, effective and easily available for allergy treatment.

  • These nasal allergy sprays are available by prescription or over-the-counter (OTC) in pharmacies for adults and children. They can be combined with oral antihistamines if needed.
  • Are often used as a single, first-line choice for hay fever (allergic rhinitis). They may be slightly more expensive than oral non-prescription antihistamines, but have fewer side effects (such as drowsiness) and drug interactions.
  • Generic and store brand can be found to help lower your cost.

Longer-acting (second generation) antihistamines (Table 2) are considered non-sedating (or less sedating) antihistamines and are preferred over first generation antihistamines, especially in children. These medications do not require a prescription, and come as oral tablets. Antihistamine eye drops for eye allergies are also available.

  • Over-the-counter oral cetirizine (Zyrtec) and levocetirizine (Xyzal) may be the most likely second generation antihistamines to lead to drowsiness; if this occurs, the medicine can be taken at bedtime.
  • Most are available in once-a-day dosing, and do not interfere with learning in children like the sedating first generation antihistamines. They are affordable and can be bought at the pharmacy in generic or store brands to save money.
  • Some products also come as an antihistamine nasal spray, for example azelastine (Astelin, Astepro) and olopatadine (Patanase). Astepro was approved for OTC use in June 2021. Drowsiness may still occur with these nasal sprays.
  • Dosing recommendations for children are listed on the OTC Drug Facts Label; if you have questions check with your pharmacist or physician.
  • Injectable certirizine (Quzyttir) was approved by the FDA in October 2019 to treat acute urticaria (hives) in patients 6 months of older. Its use is not recommended in pediatric patients less than 6 years of age with impaired kidney or liver function

Shorter-acting (first generation) antihistamines (Table 3) are available primarily as OTC products and relieve mild-to-moderate allergy symptoms.

  • A major drawback of this class is that they can also cause significant drowsiness.
  • In addition, these antihistamines can blunt learning in children (even in the absence of drowsiness).
  • These antihistamines are available in generic or store brands and are inexpensive.

Decongestants (Table 4) may also be helpful in reducing symptoms such as nasal congestion, but have no effect on prevention of allergy symptoms.

  • These agents relieve congestion by reducing swelling and mucus formation within the nasal passages or around the eye.
  • Nasal spray decongestants should not be used for more than several days because they can cause a "rebound" effect and make the congestion worse. Decongestants in pill form do not cause this effect.
  • OTC pseudoephedrine has been restricted in the U.S. and customers 18 years and older must sign for it with a valid ID. There is a limit on daily and monthly purchase amounts, and it is kept behind the pharmacy counter. Pseudoephedrine can be used to make illicit methamphetamine. 

Cromolyn sodium (Table 5) is available as a nasal spray (Nasalcrom) for treating hay fever. Eye drop versions of cromolyn sodium are also available for itchy, bloodshot eyes.

Leukotriene inhibitors (Table 6) like montelukast (Singulair) are oral prescription medicines approved to help control asthma and to help relieve the symptoms of seasonal allergies. Singulair is used for allergic rhinitis only after other treatments have failed due to the possibility of neuropsychiatric side effects.

If you already take Singulair to prevent asthma or allergy symptoms, do not use an extra dose to treat exercise-induced bronchoconstriction. Always have a short-acting beta-agonist inhaler, such as albuterol, on hand for sudden breathing emergencies.

Immunotherapy for Allergies

Oralair (mixed grass pollens allergen extract) sublingual tablets are an oral immunotherapy used to treat allergic rhinitis that is caused by certain grass pollens (sweet vernal, orchard, perennial rye, timothy, and Kentucky blue grass) in people ages 10 through 65 years. Oralair is used to treat sneezing, a runny or itchy nose, congestion, or itchy, watery eyes due to these grass pollens.

  • Oralair is the first sublingual (under the tongue) allergen extract tablet approved in the U.S. Oralair is taken for about four months before the expected start of the grass pollen season and is continued throughout the grass pollen season.
  • The first dose of Oralair is given in the clinic; after the first dose it can be taken at home.
  • People affected by hay fever may suffer from repetitive sneezing, nasal itching, runny nose, nasal congestion, and itchy and watery eyes and may need allergy shots; however, for those with certain grass allergies Oralair may be an alternative.

Other prescription oral (sublingual) immunotherapy agents for allergic rhinitis include:

  • Grastek (timothy grass pollen allergen extract)
  • Odactra (house dust mite allergen extract)
  • Ragwitek (ragweed pollen allergen extract)

Immunotherapy injections (allergy shots) are occasionally recommended if the allergen cannot be avoided, oral treatments are not effective, or symptoms are hard to control. Regular injections of the allergen are given, with each dose slightly larger than the previous dose. Allergy shots keep your body from over-reacting to the allergen. They do not work for everybody and require frequent visits to your doctor.

Tables: Common Allergy Treatments* 

Table 1: Nasal Corticosteroid Sprays

Generic name

Brand name 


Beconase AQ, Qnasl


Rhinocort, Rhinocort Allergy


Omnaris, Zetonna


Children’s Flonase, Flonase Allergy Relief, Flonase Sensimist, Flonase, Xhance




Nasacort Allergy 24HR

Table 2: Second Generation Antihistamines (non-sedating or less-sedating)

Generic name

Brand name

azelastine nasal spray

Astelin, Astepro (OTC) 

azelastine and fluticasone

Dymista (an antihistamine and nasal corticosteroid combination spray)


Zyrtec, Children's Zyrtec Allergy, Quzyttir (prescription injection for hives)


Clarinex, Clarinex Reditabs


Allegra, Allegra ODT, Allegra Allergy, Aller-Ease,


Xyzal Allergy 24HR


Alavert, Claritin, Claritin RediTabs, Claritin Allergy

olopatadine nasal spray


Table 3: First Generation Antihistamines (sedating)

Generic name

Brand name


Bromax, Veltane

carbinoxamine maleate

Karbinal ER Oral Suspension









Table 4: Decongestants (oral, nasal, and ophthalmic)

Generic name

Brand name

naphazoline nasal drops


naphazoline / pheniramine ophthalmic 

Naphcon-A, Opcon-A, Visine

naphazoline ophthalmic

Clear Eyes

oxymetazoline nasal

Afrin Sinus

oxymetazoline ophthalmic

Visine LR, Upneeq


Nasop, Sudafed PE, Neo-Synephrine, Triaminic


Benzedrex Inhaler


Nasofed, Sudafed


Triaminic decongestant

*Note: products can be a component of a combination product, not all brands listed. **Federal regulations require that pseudoephedrine is kept behind the pharmacy counter, and you will need to sign for it. Pseudoephedrine has been used illegally to make methamphetamine. 

Table 5. Cromolyn

Generic name

Brand name

cromolyn sodium

Nasalcrom Nasal Spray

Table 6. Leukotriene inhibitors

Generic name

Brand name




Severe allergic reactions (anaphylaxis), for example due to bee stings or nut allergies, usually requires epinephrine injection.

Epinephrine (Adrenaclick, Auvi-Q, EpiPen) can be life saving when administered soon after exposure by patients, caregivers, or bystanders. Recently, less expensive, generic products have become available on the market.