What Causes Allergies? A Guide to What's Going On Inside Your Body

We sprung the calendars ahead this week and it's officially allergy season, the perfect time to nail down what causes allergies and how to avoid them, because, let’s be honest:

No one wants seasonal allergies. No one.

So let’s get to it! In this post:

  • What causes allergies
  • The Allergic Response (aka what happens in your body when you have an allergy)
  • Histamine and antihistamines
  • How to avoid seasonal allergies

What Causes Allergies?

Allergies are immune responses to external substances that don’t generally cause a reaction in other people exposed to the same material. For example, pollen, peanuts, bee venom, and more.

These substances or “triggers” are identified by your immune system as a “harmful” agent and it creates a chain reaction where it produces antibodies to “protect” you from the foreign substance. This results in inflamed sinuses, skin, airways or the digestive tract and system.

What causes allergies is then a combination of your genetic predisposition to a certain trigger or allergen and your body’s immune system response to it.

The severity of the allergy isn’t depending on the allergen but on the individual immune response, going from a minor irritation or sneeze, to a potentially life-threatening condition called “anaphylaxis.”

What Causes Allergies: Common Triggers

There are multiple types of allergens, but these are the most common ones causing allergies in the US.

  • Airborne: pollen, dust mites, mold,  perfume, animal fur. Asthma, a common consequence of airborne allergens affects 24 million people in the US.
  • Insect Stings: bees, wasp or mosquito bites 5% of the population presents insect bite allergies
  • Medications: penicillin or penicillin-based antibiotics in most cases. 10% of Americans report a penicillin allergy.
  • Foods: nuts, peanuts, soy, wheat, soy, shellfish, fish, eggs, and dairy. Over 4.4 million children in the US have been diagnosed with food allergies.
  • Latex: or other substances relative to touch. 1 to 6 percent of Americans have a latex allergy

What Causes Allergies: Environment vs. Genetics

There is no definitive answer as to what causes allergies and why some people are affected by a particular allergy, while others live allergy-free lives, even if they have markers for it.

However, studies show that both genetics and environmental factors are important in the development and rise of allergies.

It is possible that the first time a person comes in contact with an allergen their body may not produce a reaction, but save the information gathered by the immune system and label a harmless element as a threatening one. Once the individual is sensitized to that specific allergen future exposures will produce an allergic reaction, ranging from mild to serious.

  • Genetics and Hereditary Conditions: a child has a 30 to 50% chance of inheriting a tendency to be allergic if one of their parents are allergic. Interestingly enough, the allergens that affect said child do not have to be the exact same one.

    For example, a person with asthma may have a child with a peanut allergy and vice-versa. 
    If both parents are allergic the likelihood of presenting allergy sensitivities increased to 80%. Genetics predisposition may also be related to gender, with the mother being a more likely agent in passing allergy sensitivities to a female child and fathers to a male child.
  • Environmental Factors: the “environment” you live in will expose your immune system to a particular set of triggers that will increase or decrease the likelihood of developing or uncovering an allergy.

    For example, individuals living in a household with animal fur may find that they are more prone to allergic reactions to dog hair than someone never exposed to it.
  • Previous Medical Conditions: one of the least expected factors that may potentially be what causes an allergy in a family with no known allergies - is an upper respiratory infection. Respiratory system infections in six-month-old babies are more likely to become allergies or asthma later on in life, regardless of whether they are bacterial or virus-related.

There is no known final cure for allergies, but a healthy diet, preventative medicine and health practices may reduce and completely avoid allergic attacks. Additionally, there are multiple treatment options to manage these conditions, depending on what causes allergies and their severity in your body.

Everyone is different but here's what's happening when you see allergy symptoms - and some of our natural solutions.

What Happens in Your Body When You Have An Allergic Reaction

In order to keep your body safe, your body triggers a chain reaction that ends in either mildly discomforting allergy symptoms or life-threatening ones. We break it down for you:

  • The immune system reacts to a substance and mislabels it as “harmful” in a process called “sensitizing”
  • When exposed to said substance on a new occasion, the immune system produces immunoglobulin E also known as IgE and antibodies for each identified
  • The antibodies “attack” the allergen
  • Chemicals called “histamines” are released from “mast cells” rejecting and flushing out the allergen. People often think this is what causes allergies.
  • Histamines cause inflammation so that the immune system can “repair” the damage
  • You experience symptoms in the one or more areas of the body including physical reactions in the skin, throat, nose, lungs, throat, ears, sinuses, stomach lining, etc.

Related Issues:

Severe allergic reactions may develop into further complications, these are the top related issues to known allergies:

  • Anaphylaxis:  an allergy-induced reaction where breathing is restricted and/or excessive swelling of the lips, throat, tongue or fingers (as well as other body parts) occurs. It may also lead to dizziness and loss of consciousness. Anaphylaxis is mostly linked to food, medication, touch-based, and insect sting allergies than to airborne allergens
  • Asthma: immune system reaction where the airways and breathing are constricted, leading to air loss, choking and coughing. Asthma is usually connected to airborne allergens.
  • Sinusitis: inflammation of the cavities around the nasal passage, it may become a chronic condition. Some people believe that sinusitis is what causes allergies, but it is usually the other way around.
  • Ear and Lung Infections: ear ringing and clogging as well as upper respiratory (lung infections) may be connected to an allergic reaction where sinus is affected and impeding correct air passage as well as mucus release.

If you're asking yourself: Can allergies cause sore throat? Can allergies cause coughing? or Can allergies cause fever or hay fever?

The answer is yes: these are all part of the immune response to allergens, where the sore throat is the result of irritation, coughing the consequence of nasal leaking or histamine reaction (for expulsion), as well as itchiness in the skin and/or in some cases fever.

What are Histamines and Antihistamines?

The immune response to allergens brings out histamine production and we combat it with prescription and over the counter antihistamines. Here’s a brief definition of both:


An organic nitrogenous compound that participates in the immune response against allergens, but that also regulates physiological function in the gut and acts as a neurotransmitter for the brain, uterus, and spinal cord. It is a critical factor in the control and regulation of the itching sensation.

Histamines are told by the immune response that there is an allergen and act as club bouncers to get the “undesirable” element out of your system, via the mucus of the nose or skin. Essentially what causes allergies to feel uncomfortable and make us take notice.

Histamines have multiple action mechanisms:

  • Vasodilation: histamine causes blood vessels to open up and release pressure.
  • Blood Pressure Drop: due to its vasodilation properties, blood pressure may drop under increased histamine presence.
  • Nasal Mucus: vascular permeability allows mucus fluid to escape, leading to runny noses, hyper-mucus secretion, watery eyes, and nasal/sinus congestion.
  • Gastric Acid Reflex activation and acid production
  • Protects against convulsion, stress, denervation and ischemic lesions
  • May have a role to play in sleep and wake cycles


Histamine binds with specific receptors located in various cells around the body to cause the immune response we know as “allergy” symptoms. Antihistamines are chemicals that reduce the uncomfortable effects of histamine in those cell receptors, ultimately providing relief for anything from nasal congestion to hives.

Antihistamines, simply put, create an opposing reaction to histamine receptors. These drugs are usually available OTC and are very effective (they’re what causes allergies to go away!)

The most common prescription an over the counter antihistamines are:

  • Desloratadine
  • Azelastine
  • Hydroxyzine
  • Cyproheptadine
  • Levocabastine

However, there are also natural antihistamines you may want to consider as an alternative option if you don’t know what causes allergies in your specific case.

  • Vitamin C
  • Flavonoids like Quercetin available in citrus fruits, apples, parsley, tomatoes, broccoli, lettuce and even onion and garlic.
  • Omega-3 Fatty Acids
  • Bromelain (usually found in pineapples!)
  • Probiotics

How to Avoid Seasonal Allergies

Say healthy and avoid those pesky reactions with these simple steps you can implement today:

  • Avoid Known Allergens: if you know what causes allergies for you, then simply make sure you avoid the triggers that lead to an allergic reaction. If you don’t know what your triggers are consider getting tested.
  • Remove Outerwear: if you’ve been outdoors practicing sports, going for a walk or just being exposed to the elements, you may reduce the chances of an allergy attack by simply removing the items of clothing you were wearing outside; the longer the exposure the more an environmental factor may come into play.
  • Wear a Mask: when gardening or doing chores outside as the seasons change to reduce pollen and airborne allergen contact.
  • Clean Filters: regularly schedule air conditioning filter cleaning to make sure clear air is circulating.
  • Neti-Pot or Nasal Spray: clean your nose as needed using a simple saline solution with a nasal spray, or a neti pot.
  • Take a Probiotic: research shows that a probiotic may have an important role in the prevention of allergies like rhinitis (or hay fever.) Taking an extra probiotic supplement can help your body fight off this year's allergies.
  • Take Vitamin C: to boost your immune system during those changing season weeks.

If you find that over the counter medication and natural remedies are not helping you keep allergies under control, please consider consulting a physician and getting help as you may need prescription medication.

Fight off seasonal allergies armed with the necessary knowledge to determine what causes allergies for you in particular, boosting your probiotic and Vitamin C intake, and keeping that histamine in check!

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