How Th2 Dominance Impacts Allergies and Immune Health

If you’re struggling with chronic immune system issues such as persistent allergies, frequent infections, or skin conditions, your immune response might be dominated by a dominant “Th2 response.” In this post, I’ll explain what “Th2 dominance” is, how it affects your health, and how to address it through functional medicine.

Understanding T Cells and How They Differentiate

T cell differentiation refers to how your naïve T cells mature into specialized effector T cells that carry out different immune functions. In the chart below, you can see how the blue naïve T cell in the middle, called a CD4 T cell, can branch out in different directions. Think of the naïve T cell as a blank slate baby saw that can grow up into different types of specialized T helper cells. Here on this chart, we show the four main types of “grown-up” T helper cells and how they function immunologically.

Ideally, your naïve CD4 T cells can mature into any of these specialized T helper cells (Th1, Th2, Treg, or Th17) as needed. They all perform important functions. Problems arise when your immune system gets stuck in one mode, such as Th2, common in people with allergies and chronic infections.

Many patients come to me with conditions that are driven by an overactive Th2 immune response, making it difficult to fully resolve their symptoms without addressing this underlying issue. Understanding and treating Th2 dominance is crucial for lasting improvement in chronic allergies, infections, and inflammation, particularly in exposed areas like the skin, nose, lungs, bladder, vagina, and GI tract.

Th2 Dominance and Chronic Inflammation: Breaking the Cycle

Th2 cells produce inflammatory cytokines, such as interleukin-4 (IL4), in response to infections or inflammation in body areas exposed to the external environment. The problem arises when these infections or inflammations persist, leading to excessive IL4 production. This signals naive T cells to create more Th2 cells, resulting in Th2 dominance—a vicious cycle of ongoing inflammation. As a result, your body remains inflamed in these areas, increasing susceptibility to infections and chronic conditions. This is why I call Th2 cells “overprotectors.”

The bottom line: To heal from these conditions, it’s essential to address Th2 dominance and get IL4 production under control. I discuss how to do this in my article How to Prevent Allergies Naturally and Feel Like Yourself Again.

Signs You Might Be Stuck in Th2 Dominance

If you experience chronic infections or inflammation in your lungs, sinuses, gut, bladder, or vagina, you may be stuck in Th2 dominance. This “overprotector” immune response just can’t quit and causes symptoms like:

• Lungs: Asthma, frequent respiratory infections, bronchitis
• Nose/Sinuses: Allergies, congestion, frequent colds
• Gut: Food intolerances, small intestinal bacterial overgrowth (SIBO), leaky gut
• Bladder: Frequent infections, interstitial cystitis
• Vagina: Recurrent yeast or bacterial infections, vulvodynia
• Skin: Excema, rashes, hives

Factors That Drive Th2 Dominance

Various triggers can push your immune system toward a Th2 response, including:

• Mold toxins
• Viral infections (herpes, shingles, Epstein-Barr virus)
• Chronic infections (like Lyme disease)
• Stress
• Environmental toxins
• Allergies and histamine overload
• Aging and cancer
• Gut microbiome imbalances

The Link Between Th2 Dominance, Chronic Infections and Autoimmune Disease

When your immune system is stuck in Th2 dominance, it inhibits the production of Th1 cells, which is not a good thing. You must mount a robust Th1 (“warrior”) response to defend against bacteria, viruses, and other pathogens. If Th1 is inhibited, it can result in:

• Frequent colds, flu, and slow recovery from infections
• Chronic viral infections like shingles or Epstein-Barr
• Recurring gut issues like SIBO or candida
• Persistent vaginal or bladder infections

Th1 cells also help suppress autoimmunity. When T1 is inhibited, your ability to combat autoimmune flares is significantly weakened. With Th2 dominance in play, unless this is addressed, it’s difficult to control autoimmune reactions. I explain this in more depth in my article T-Cell Regulation for Autoimmunity: A Functional Medicine Approach.

How to Shift Out of Th2 Dominance

In our functional medicine practice, we take this approach to helping people move out of Th2 dominance:

• Managing stress
• Cleaning up diet and gut health
• Clearing environmental toxins
• Reducing pathogen loads (such as chronic infections)
• Taking natural supplements to down-regulate the Th2 response

By addressing these factors, you can regain your health and reduce chronic inflammation from Th2 dominance.

We dive into some of the supplements for allergies in our article How to Prevent Allergies Naturally and Feel Like Yourself Again. However, if your Th2 dominance shows up in another area, such as the lungs, skin, gut, bladder, or vagina, you may need a different supplement approach.

Take Action Today

If you suspect you’re stuck in Th2 dominance or have chronic immune issues, I can help you understand and address these concerns. As an immune specialist, I’ve aided hundreds of women with strategies for restoring balance in their immune systems. Please contact me directly for assistance.

Any questions about this topic? Please ask in the comments below.