50 million people in the U.S. suffer from allergies annually. Caused by the body’s over-response to harmless outside stimuli, such as pollen, fruits, vegeta

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Table of content

Allergy Causes

There are several causes of allergic reactions; each cause depends on your body’s response to an outside stimulus. 

During an allergic reaction, your immune system overreacts to harmless substances, usually through your respiratory, digestive, or integumentary (skin) system. When the ‘unknown’ substance comes in contact with one of these systems, your body creates Immunoglobulin E (IgE) antibodies to defend itself against a seeming ‘attack’.

This production of antibodies instead ends up attacking the body itself, causing uncomfortable symptoms in the respiratory, digestive, and integumentary systems (and in some cases anaphylaxis). 

Airborne Allergens

Airborne allergens are the most common causes of seasonal allergies. Allergens such as pollen particles can enter your respiratory system as you breathe. These pollens can also get in your eyes, causing watery, burning, itching eyes. 

In the spring, when pollen spore counts are high, allergy symptoms can be especially uncomfortable. 

Some people also suffer from summer and autumn seasonal allergies, and allergy severity may differ depending on location; people that live in New England may experience allergies to oak and maple trees in the fall, whereas people living in the U.S. South may experience oak and pine allergies in the winter. 

Many people are also allergic to airborne environmental allergens, such as mold, dust, and bed bugs. Allergy symptoms caused by environmental allergens can arise pretty much all year long. 

Food Allergens

It’s estimated that 32 million people in the U.S. suffer from food allergies. This is when your body has an allergic reaction to foods you eat or comes in contact with (via rubbing your eyes or contact dermatitis, such as skin rashes).

The most common food allergies are nuts, shellfish, and dairy (though some people also suffer from fruit and vegetable allergies, too).

Some children may outgrow food allergies, but not all will. Most people don’t develop shellfish allergies until adulthood. 

When foods enter the body, antibodies are released, causing swelling, pain, and difficulty breathing. Severe allergic reactions to food may cause anaphylactic shock. 

Animal Allergens

Animal allergens are absorbed into the body via the respiratory, digestive, and integumentary systems. People can inhale allergens (such as animal dander) or ingest them (such as eating chicken or eggs). Airborne allergens can also become lodged in the eyes. 

Sometimes touching an animal can also cause contact dermatitis (allergic reaction through the skin). Simply being exposed to animals or coming close to animal feces can cause an allergic reaction for some. 

Types of Allergies

There are six main types of allergies, including seasonal, environmental, drug, food, latex, and contact dermatitis. All allergies are simply the immune system overreacting to small particles of unrecognized matter entering the body. 

Some people may experience symptoms from breathing in allergens, from digesting them, and or from touching them. Or, some may experience symptoms from all three. 

Seasonal Allergies

Seasonal allergies are one of the most common types of allergies. In the spring, summer, and autumn, plants spread pollen; this pollen becomes airborne and can more easily enter the respiratory system and eyes, causing uncomfortable symptoms. 

The most common seasonal allergens include:

  • Birch trees

  • Cedar trees

  • Grasses 

  • Hay fever

  • Lamb's quarters

  • Oak trees

  • Pigweed

  • Ragweed 

  • Sagebrush

  • Tumbleweed

  • Weed 

Seasonal allergies usually only affect people during certain seasons. (Though some people in warmer climates may experience seasonal allergies year-round). 

Environmental Allergies

Environmental allergies are similar to seasonal ones; yet, these allergies can cause uncomfortable symptoms pretty much any time of year — as they aren’t caused by pollination. These allergens can be found around the home or in nature.

If you suffer from uncomfortable symptoms year-round, you may want to get tested for environmental allergens in addition to seasonal allergens. 

Animal Allergies

Animal allergies are another common type of allergic reaction. The most common types of such allergic reactions include pet dander, contact with farm animals, and insect stings and bites. 

Allergic reactions to animal hair, products, venom, and proteins can be moderate to severe. They can result in symptoms, such as hives, respiratory issues, or even anaphylactic shock in some severe cases. 

Pet Allergies

Allergies to pet dander are very common. 

Researchers estimate that 15-to-20% of Americans are allergic to dogs and cats. Other common pet allergies may include rodents, insects (and insect bites), and birds. 

The cause of rodent and bird allergies is often hair, fur, feathers, and feces. Less common are allergies to snakes and other reptiles. 

Pet allergies can cause more extreme symptoms than other animal allergies, as pets are usually kept in confined spaces (inside a house, specific room, cage, etc.). Airflow is almost always more restricted indoors than outdoors. 

Pets can also leave fur, dander, and droppings on furniture; this can be especially problematic with upholstered furniture. 

Farm Animals

Farm animal allergies are also common; yet, they’re less problematic than pet allergies. Most of us aren’t required to spend long amounts of time with farm animals, so avoiding these animals is often pretty easy. 

Yet, many people that have allergies to farm animals may also have food allergies, too. Eating chicken, eggs, beef, and other animal proteins may cause an allergic reaction. 

The easiest way to avoid allergic reactions to farm animals is to avoid exposure to the animals themselves and avoid eating animal proteins should you have adverse reactions to these foods. 

Some vaccines contain eggs, so you’ll want to tell your doctor of any allergies before getting vaccinated. 

Bee Stings

Bee stings are possibly the most common animal allergy next to pets is insect bites and stings. While only 1-to-3% of people are allergic to bee stings, most people simply don’t know they’re allergic because they haven’t been stung yet.

Bee sting allergies can result in hives, raised skin, red skin, itching, difficulty breathing, and anaphylactic shock. Bee, wasp, and hornet stings result in more animal-related deaths than for any other reason (including animal attacks and rabies). 

If your family members are allergic to bee stings, you may want to get tested to see if you’re also allergic. If so, you’ll want to avoid bees and carry an epinephrine pen in case of emergency. 

Mold Allergies

Another common allergen is mold. 

Mold allergies can cause severe symptoms, such as shortness of breath and anaphylaxis. This type of allergy can be even more severe in patients that suffer from asthma and other lung conditions. 

Some types of mold (such as black mold) can result in more severe symptoms, while other types of mold may only result in mild or moderate symptoms. The amount of mold and its location may also be a factor in symptom severity. 

Dust Mites/Cockroach Allergies

Bugs such as dust mites and cockroaches can lead to severe allergic reactions as well. Symptoms of both dust mite and cockroach allergies can be exacerbated by lung conditions, such as asthma. 

Cockroach allergic reactions are most common in children. 

Dust mite allergies are very common in both children and adults. People allergic to this type of allergen are allergic to both the mites themselves and their excrement. Symptoms of dust mite allergies are similar to those of seasonal allergies.

Cigarette Smoke Allergy

Some people also suffer from cigarette smoke allergies. These allergic reactions are usually the result of allergies to chemicals found in cigarettes — not the active ingredient (nicotine) itself. 

An allergic reaction can be the result of inhaling cigarette smoke or from contact dermatitis. When particles from cigarette smoke land on the skin, they can cause rashes, skin redness, and itching for those suffering from cigarette allergies. 

Children that are exposed to secondhand smoke are also more likely to suffer from allergic reactions — not only to tobacco products and chemicals but also to other allergens — throughout their lives. 

Drug Allergies

Drug allergens are absorbed through the digestive system but may also enter the body through the respiratory system or through the dermis. The most common drugs that may result in severe allergic reactions include:

  • Antibiotics

  • Antibiotics sulfa drugs

  • Anticonvulsants

  • Aspirin

  • Chemotherapy drugs

  • Ibuprofen 

  • Morphine

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Penicillin

Talk to your doctor about risk factors associated with allergic reactions to the above drugs. 

Food Allergies

Food allergies have become more common in the past few decades. 5.6 million children suffer from food allergies in the U.S. These allergies are the result of the body’s response to harmless foods that enter the system. Most symptoms happen as the food enters the body — not during digestion. 

Common Food Allergies

Food allergies differ from food sensitivities and intolerances. Food sensitivities and intolerances usually affect the digestive system after the food has entered the stomach. Most sensitivities and intolerances affect the intestinal system.

Allergy symptoms happen when the food enters the mouth and esophagus; most symptoms are related to the upper-digestive system, including the mouth and throat.

The most common food allergens include:

  • Dairy

  • Eggs

  • Fish

  • Legumes (peanuts)

  • Nuts

  • Shellfish

  • Soy 

  • Tree nuts

  • Wheat

The most common food allergy symptoms include swollen mouth, lips, tongue, and throat. Food allergies can result in blue face and lips, throat closing, and anaphylaxis. 

Oral Allergy Syndrome

Similar to food allergies, oral allergy syndrome happens when your body has an allergic reaction to a protein in uncooked fruit or vegetables. 

Most people that suffer from this condition have seasonal allergies; the proteins in food are similar to the proteins in seasonal allergens, such as pollen, grass, and ragweed. Just as the body doesn’t recognize the seasonal allergen, it doesn’t recognize the protein in the uncooked fruit or vegetable. 

Oral allergy syndrome can affect both the upper and lower digestive systems. It usually results in swelling, itching, and esophageal swelling and pain. While most people with this condition don’t experience serious symptoms, oral allergy syndrome can cause severe discomfort and pain for others.

If you think you may have oral allergy syndrome, you’ll want to get tested for seasonal allergies. Doctors recommend avoiding raw fruits and veggies, cooking problem foods (the proteins get broken down in the cooking process), and taking antihistamines. 

You may also want to carry an epinephrine pen in case of anaphylactic shock. 

Latex Allergy

Some people are also allergic to natural rubber latex products. Allergic reactions can happen when you come in contact with latex via your skin or through foods (some latex reactive foods, such as avocado and some tree nuts contain rubber tree sap.

The most common cause of a latex allergy is coming in contact with a latex glove or condom. 

Reactions can be moderate-to-severe and symptoms include red skin, hives, itching, and anaphylactic shock.  

Contact Dermatitis

Contact dermatitis is an allergic reaction that happens through the skin. 

Skin reactions can be caused by allergens such as latex, animal dander, animal feces, poison ivy, and more. Symptoms are similar to those of other allergens. 

Treatments may include steroid creams, steroid injections, oral antihistamines, and epinephrine. 

Allergies Symptoms

Allergy symptoms often vary from person to person. Some people may experience mild-to-moderate symptoms, such as dry eyes, itchy eyes and nose, coughing, sneezing, runny nose, sneezing, or skin redness. 

Others may experience moderate-to-severe symptoms, such as extreme itching, swelling, and hives. 

Some people may experience life-threatening symptoms such as anaphylaxis.  

Moderate Symptoms

The most common symptoms of allergies are similar to cold and flu symptoms. Airborne allergens may attack the respiratory system or epidermis first, while food allergens often attack the mouth and esophagus. 

The most common moderate allergy symptoms include:

  • Chest tightness

  • Cough

  • Esophageal swelling 

  • Hives

  • Itchy eyes 

  • Itchy lips

  • Itchy mouth

  • Itchy nose

  • Itchy skin

  • Rashes

  • Red skin

  • Runny nose 

  • Shortness of breath

  • Sinus pressure/pain

  • Sneezing 

  • Stuffy nose (allergic rhinitis)

  • Swollen eyes

  • Swollen face

  • Swollen lips

  • Swollen tongue

  • Watering eyes (conjunctivitis)

  • Watery nose

  • Wheezing

Severe Symptoms

Depending on the severity of your allergy, you may experience more severe symptoms.

Some people suffer from extreme allergic reactions to foods, pet dander, bee stings, and environmental allergens. Some of the most common severe symptoms of allergens may include difficulty breathing, esophageal swelling, blue lips or face, and anaphylaxis.

If your symptoms are severe, you’ll want to keep an epinephrine pen (EpiPen) on hand for emergencies. Severe symptoms may lead to anaphylactic shock, a closed esophagus, and even death. 

Allergies Treatment

Luckily, there are plenty of treatment options for all three types of allergies (food, seasonal, and environmental). 

Before you start any type of allergy treatment, you should get tested. Testing ensures you understand the severity of your allergy and all possible allergies — not only the ones you’ve experienced symptoms with. 

The most common treatments for allergies include antihistamines, nasal sprays, eye drops, and immunotherapy. 

Allergy Testing 

Before taking any medications, you’ll want to know what allergies you suffer from. Allergy testing is available for food, seasonal, and environmental allergies. Your doctor can refer you to a specialist, or you can make an appointment with an allergist for testing.

At-home testing kit companies like EverlyWell now offer allergy testing at home. Simply order your test, follow the instructions, and mail your sample to the lab. You should get your results in a few days.

You can also take allergy tests directly through some allergy medication providers now, too, making testing and treatment a seamless experience.  

Oral Antihistamine

One of the most common treatments for seasonal and environmental allergies (including pets, mold, insects, and more) is oral antihistamines. These are available in both over-the-counter (OTC) and prescription strength.

Antihistamines block histamines (the organic compound that attacks allergens but also causes inflammation and itching). They can relieve redness, itching, swelling, and other symptoms. 

Antihistamines are available in prescription and OTC strengths. OTC antihistamines are commonly thought to be less expensive than their prescription counterparts, but this isn’t necessarily the case.

Prescription antihistamines contain personalized amounts of active ingredients, meaning you’ll never get too much or too little of an active ingredient. OTC antihistamines can cause adverse side effects or may not work as effectively as prescription doses. 

Online allergists like Picnic sell personalized prescription antihistamines; pay for your prescription and consultation in one fee, and medications are delivered right to your home or office. 

Intra Nasal Spray

Nasal sprays usually target nose-related symptoms, including congestion, stuffy nose, itchy nose, post-nasal drip, and sneezing. They often also address other symptoms (often related to eye discomfort), such as itchy eyes, puffiness, and watery eyes. 

Some nasal sprays are simply liquid antihistamines (including OTC sprays), while other sprays contain steroids to combat allergy symptoms. All steroid-based nasal sprays are available by prescription only. 

Nasal sprays are fast-acting medications that can relieve symptoms on the spot (but work best when taken up to two months before allergy season). 

These sprays have a bad reputation for having a bad taste or smell, so some nasal sprays are also taste-and-aroma-free. 

Eye Drops

If you suffer from itchy, dry, irritated, puffy eyes, you may want to opt for prescription or saline-based eye drops.

Medicated eye drops contain antihistamines that help to reduce puffiness, irritation, and itchiness. They are usually taken preemptively or on the spot to ease symptoms. Most people don’t opt for prescription eye drops as they shouldn’t be used on a daily basis, and most doctors recommend only using them for severe allergic reactions.

Some medicated eye drops can be used in conjunction with oral or nasal allergy medications. Saline drops are sold over the counter and offer fast-acting relief from eye allergy symptoms; they can also be used with other types of medicated allergy medications.  


Immunotherapy is when you introduce very small amounts of allergens to your system to allow it to become accustomed to these allergens. Over time, your body won’t see the allergen as a threat and won’t release antibodies into your system. 

Allergy Shots

A somewhat newer allergy prevention and treatment option are allergy shots. These shots are administered by a doctor over the course of a few years (usually between three-and-five years). 

Allergy shots introduce a small amount of the allergen into your system. Your body gets used to the allergen, realizes it’s not a threat, and gradually stops releasing antibodies to fight the allergen. 

The downside is that these shots must be administered a few times a year, and it may take up to five years to see results. They’re also pretty expensive, as they run around $5,000 (or $1,000 per year) and aren’t covered by most health insurance plans. 

Immunotherapy Drops

Immunotherapy drops are similar to allergy shots. The biggest benefit to the drops versus the shots is that you can take them in the comfort of your own home. 

Developed by doctors at NYU, Berkeley, and Johns Hopkins, these drops are as effective as allergy shots. They contain small amounts of allergens to help your body build up an immunity to whatever you’re allergic to.

Simply place a few drops underneath your tongue, and your body should start to build resistance to the allergen over time. Before taking the drops, you’ll need to get tested for allergies to determine your dosage and formula. 

These drops cost between $65 and $95 a month; you may need to take them for up to three years. 


If you suffer from severe allergies to foods, insects, and other allergens, you probably carry an epinephrine pen with you at all times for emergencies.

Epinephrine is a drug that, when injected into the system, constricts muscles and relaxes the muscles of the lungs, allowing air to flow freely.

Using such a drug is reserved for emergency use only (meaning it isn’t preventative or designed to be used on a regular basis).

If you suffer from serious allergies, you’ll simply want to avoid allergens.

You don’t need to suffer from seasonal and environmental allergies; there are plenty of treatment options available — many at an affordable or low cost through online pharmacies and allergists.