What is my body trying to do when it has an allergic reaction?

Overview

Why does my body overreact to something as simple as pollen or peanuts? It’s a common and valid question. Allergies can feel confusing, especially when everyday substances suddenly cause irritation, swelling, or discomfort.

Your immune system is designed to protect you, but sometimes it becomes overly defensive. When you’re exposed to something harmless, such as pollen or pet hair, your body mistakenly interprets it as a genuine threat.

This triggers a chain of immune responses that appear as allergy symptoms. Understanding what happens in your body during an allergic reaction can help explain why these reactions occur and how they can be managed.

What is an allergy?

An allergy occurs when your immune system mistakenly identifies a harmless substance as dangerous and reacts to it. Common allergens in Australia include:

• Grass and pollen
• Dust mites
• Pet dander
• Certain foods (e.g., peanuts, shellfish)
• Insect stings or bites
• Medications

How the immune system normally works

In everyday situations, your immune system protects you from real threats such as viruses, bacteria, and other harmful organisms. It uses antibodies to recognise and eliminate germs, helping to keep you healthy.

However, during an allergic reaction, the immune system misidentifies a harmless substance and mounts an unnecessary defence response.

What happens during an allergic reaction?

During an allergic reaction, your immune system overreacts to something that is usually harmless, triggering symptoms such as sneezing, itching, swelling, or breathing discomfort.

Exposure to the allergen

The process begins when your body encounters a harmless substance, such as pollen, but mistakenly interprets it as a threat.

• Your immune system wrongly identifies the allergen as dangerous.

Immune system response

To protect you, your immune system produces a specific antibody called immunoglobulin E (IgE).

• IgE binds to immune cells known as mast cells and basophils.

Histamine release

When you encounter the same allergen again, these immune cells release histamine and other chemicals into the bloodstream.

Histamine causes inflammation and leads to common allergy symptoms such as:

• Sneezing
• Itchy or watery eyes
• Runny nose
• Hives
• Swelling
• Coughing or wheezing

Visible symptoms

These symptoms are your body’s way of trying to flush out or block the allergen:

• Sneezing → helps expel irritants like pollen.
• Watery eyes → wash away allergens.
• Mucus production → traps and removes irritants.

Why does the body overreact?

Your body overreacts because the immune system becomes overly sensitive and begins treating harmless substances as threats. Instead of ignoring them, it activates defence mechanisms that lead to allergy symptoms.

Several factors influence why allergies develop, including:

• Genetics: Allergies often run in families.
• Environment: Pollution, diet, climate, and lifestyle may increase sensitivity.
• Changes in adulthood: Hormonal shifts, immune changes, or new exposures can trigger allergies later in life.
• Hygiene hypothesis: Reduced exposure to microbes during childhood may lead to a more reactive immune system.

Types

Allergic reactions can range from mild to severe and may present differently from person to person. Understanding the type of reaction you’re experiencing can help guide appropriate treatment and care.

• Mild: Sneezing, itching, rashes, and a runny nose.
• Moderate: Swelling, persistent coughing, or asthma-like symptoms.
• Severe (anaphylaxis): Difficulty breathing, a sudden drop in blood pressure, dizziness — a medical emergency.

Note: Always seek urgent medical help if you notice signs of anaphylaxis.

How allergies are diagnosed

Diagnosing allergies starts with identifying your symptoms and understanding potential triggers. A GP will usually review your medical history and may recommend further testing to confirm the cause.

• Discussion of symptoms and medical history
• Skin prick testing
• Blood tests to detect immunoglobulin E (IgE) levels

Recognising your specific triggers allows for more accurate management and tailored treatment strategies.

Treatment tips

Effective allergy management focuses on reducing exposure to triggers and controlling symptoms. Depending on the severity, your GP may recommend:

• Avoiding known allergens wherever possible
• Using antihistamines or nasal sprays for symptom relief
• Considering immunotherapy for long-term desensitisation
• Carrying an EpiPen for severe allergies, if prescribed
• Staying informed about high pollen days in Australia

How Hola Health can help

Hola Health makes allergy care simple, accessible, and tailored to your needs.

• Speak with an online GP to diagnose and manage allergy symptoms
• Receive prescriptions for antihistamines or allergy medications via eScript
• Get personalised allergy management plans from experienced doctors
• Access safe, convenient care Australia-wide

Conclusion

Allergies are your body’s way of overprotecting you — a “false alarm” from an immune system that responds too aggressively. With the right care and support, most people can keep their symptoms under control and maintain their usual daily activities.

If you’re experiencing frequent or worsening allergic reactions, speaking with a Hola Health GP online can help you identify triggers and find the most effective treatment plan.

FAQs

Why does my body suddenly react to things I wasn’t allergic to before?

Allergies can develop later in life due to hormonal changes, shifts in immune function, or new environmental exposures.

What does histamine do in an allergic reaction?

Histamine causes inflammation, swelling, itching, and mucus production — all part of the body’s attempt to defend itself.

Are allergies a sign of a weak immune system?

No. Allergies reflect an overreactive immune response, not a weakened one.

Can allergies go away over time?

Some allergies, especially in children, may improve or resolve over time, while others can persist or appear later in life.

How can I calm an allergic reaction naturally?

Rinsing your eyes or nose, showering after outdoor exposure, and avoiding known triggers may help ease symptoms. Always follow your GP’s advice, especially for moderate or severe reactions.