Pathophysiology of Allergies

Allergy comes from the Greek words “Allos” and “Ergon.” Allos means other and ergon means reactivity. Essentially, allergies are reactions to molecules from outside of your own body. These are things you can breathe or take in (i.e. foods, dander, bee stings, mold, medication, pollen, etc), or come in contact with skin (i.e. latex, lotions, and soaps).  Allergies are caused by an immune-mediated response from antigens. Antigens that cause an allergic reaction are called allergens. 

An allergic reaction essentially happens in two steps with first exposure, or sensitization, and subsequent exposure, which can get a lot more serious. People who generally have these allergic reactions have a genetic predisposition to unknown allergens. This means they have specific genes that cause their T-helper cells to be more hypersensitive to certain antigens. Since production of T-helper cells is genetically linked, allergies tend to run in families. 

One of the major mediators in an allergic reaction is called histamine. The immune system consists of mast cells that release histamine. Ever have difficulty breathing during allergy season? This is because histamine binds to H1 receptors in the bronchi which then causes smooth muscles to contract in our lungs. Or how about itching and swelling? Histamine attaches to receptors in the blood vessels which causes blood vessel dilation and increase vascular permeability. Essentially what this means is due to the blood vessel dilating or expanding, there is increase blood flow in the cells that lead to leakage into the interstitium (the space between the cells). This surge in blood flow and “leakage” is the cause of swelling and itching.

Allergy Symptoms

Some common signs and symptoms include:

  • Nasal congestion
  • Itchy and watery eyes
  • Sneezing
  • Stuffy or runny nose
  • Scratchy or sore throat
  • Cough due to postnasal drip

Types of Allergic Reactions

There are 4 types of allergic reactions:

  • Type I: Immediate Hypersensitivity
  • Type II: Cytotoxic Reaction (Antibody-dependent) 
  • Type III: Immune Complex Reaction
  • Type IV: Cell-Mediated (Delayed Hypersensitivity)

With seasonal allergies in full bloom, Type 1 allergic-reactions is an IgE-mediated response that causes these immediate symptoms for most seasonal allergy sufferers. They are both systemic or localized, and in worst-case-scenarios may lead to anaphylaxis if not treated. 


Now that we know histamine is the major player in allergies, it makes sense to take anti-histamines to help prevent allergy symptoms from occurring or worsening. 

  • Claritin/Alavert (Loratidine)
  • Zyrtec (Cetirizine)
  • Allegra (fexofenadine)
  • Bendaryl (Diphenhydramine)
  • Xyzal (Levocetirizine)

OTC Anti-Histamine Side-Effects

These OTC antihistamines may help alleviate some of your symptoms, but they come with associated side effects:

  • Drowsiness
  • Dizziness
  • Nausea
  • Restlessness
  • Dry mouth
  • Confusion
  • Moodiness

CBD for Allergy Relief

A clinical study showed CBD may stop our cells from releasing histamines. Another study published in ‘The Journal of Leukocyte Biology ‘ suggested that cannabinoids impaired T-cell activation. When we come in contact with allergens, our immune system activates our T-helper cells which in turn cause histamine release. By impairing T-cell activation, you’re essentially stopping histamine production. Allergens come in contact with skin also. This study showed that CBD may help calm the skin by reducing inflammation.  It is known that people with pre-existing skin issues tend to have more skin allergies and unfortunately coming in contact with specific allergens can trigger a flare up. CBD may be a more natural solution in keeping allergy-mediated flare-ups at bay with its anti-inflammatory properties.

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