What Is Histamine and Why Does It Trigger Allergy Symptoms?

What Is Histamine and Why Does It Trigger Allergy Symptoms?

Sneezing, a blocked or runny nose, and itchy, watery eyes are familiar signs of hayfever.2 If you have ever wondered what is histamine and why it is linked with these symptoms, the answer starts with your immune system. For a broader introduction, our guide to what hayfever is and what causes it explains the condition and its common triggers.

Histamine is a natural chemical messenger made by the body. It has several normal roles, but during an allergic response it can be released in larger amounts and contribute to common hayfever symptoms.24

BreathMor® is a clinically trialled* nasal spray containing a naturally derived active ingredient from Cinnamomum verum (Cinnamon) stem bark extract. It is non-drowsy and helps to provide temporary relief from seasonal hayfever symptoms, including sneezing, nasal congestion, runny nose, itchy eyes, nasal itching and eye redness.

Important: ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Adults only. If symptoms persist, talk to your health professional. Contains Sulfites (Sodium bisulfite).

Key Takeaways

  • Histamine has several normal roles in the body.4

  • Allergens such as pollen can trigger histamine release from mast cells.24

  • Histamine contributes to common hayfever symptoms.24

  • Hayfever is different from histamine intolerance.5

  • Some antihistamines can cause drowsiness.3

What Is Histamine and How Does It Cause Allergy Symptoms?

Histamine is produced naturally and stored mainly in immune cells, including mast cells and basophils. It is not only involved in allergies. Histamine also plays a role in immune signalling, stomach acid production and the sleep-wake cycle.4

So, if you have ever wondered what histamine actually is, it is more accurate to think of histamine as a chemical messenger rather than an allergen itself.4

What Happens When Mast Cells Release Histamine?

In someone with an environmental allergy, the process can look something like this:24

  1. An allergen such as pollen24 reaches the nose or eyes.

  2. The immune system recognises it as a trigger.

  3. Mast cells become activated and release histamine and other inflammatory chemicals.

  4. Histamine acts on nearby nerves, blood vessels and tissues.

  5. Familiar hayfever symptoms can follow.

Antihistamines generally work by blocking the effects of histamine after it has been released.3

How Does Histamine Cause Hayfever Symptoms?

Once histamine and other inflammatory chemicals are released, they can contribute to several familiar symptoms:24

  • Sneezing: irritation of sensory nerves can trigger the sneeze reflex.

  • Runny nose: nasal secretions can increase.

  • Nasal congestion: swelling in the nasal lining can create a blocked feeling.

  • Itchy nose and eyes: histamine can stimulate sensory nerves.

  • Red or watery eyes: inflammation can contribute to redness, itching and watering.

Why Can Hayfever Feel Worse Some Days or Seasons?

If your hayfever seems manageable one day and more disruptive the next, changing allergen exposure may be part of the reason. Our guide to the early signs of hayfever can also help you recognise patterns over time.

Pollen levels can vary according to the season, location, weather and wind conditions.12 When more of the pollen you are sensitive to is in the air, symptoms may become more noticeable. This does not necessarily mean your underlying allergy has suddenly become more severe. You may simply be experiencing greater exposure.

BreathMor® is not an antihistamine. BreathMor® works earlier in the allergic response at the mast cell level, helping to reduce histamine release before symptoms such as nasal itching, sneezing and itchy eyes take hold.* BreathMor® is a clinically trialled* nasal spray for adults that helps to provide temporary relief from seasonal hayfever symptoms, including sneezing, nasal congestion, runny nose, itchy eyes, nasal itching and eye redness.

Histamine Allergy the Same as Histamine Intolerance?

Is a Histamine Allergy the Same as Histamine Intolerance?

People sometimes search for “what is histamine allergy”, but histamine itself is not usually what someone with hayfever is allergic to.

The trigger may instead be an environmental allergen such as pollen, dust mites, mould or animal dander. Histamine is one of the chemicals released by the body during the allergic response.2

Histamine intolerance is different and remains an evolving area of research.5

Category Allergic response Histamine intolerance
Main trigger An allergen such as pollen24 Often discussed in relation to histamine from foods5
What happens The immune system activates mast cells and histamine is released24 The body may have difficulty processing or breaking down histamine5
Typical context Sneezing, congestion, runny nose and itchy eyes2 Symptoms may overlap with digestive issues, headaches and food reactions5

Why Is Histamine Intolerance Still Debated?

There is currently no single universally accepted diagnostic test for histamine intolerance.5

Diamine oxidase, or DAO, is often part of the conversation because this enzyme helps break down histamine. However, DAO testing alone does not provide a simple answer, and symptoms can overlap with many other conditions.5

If you suspect food-related histamine may be affecting you, speak with a healthcare professional before making major dietary restrictions or trying to self-diagnose.

Why Do Some Antihistamines Make You Feel Drowsy?

Histamine also works in the brain, where it plays a role in maintaining wakefulness. This helps explain why some medicines that block histamine can also make you sleepy.34

First-generation antihistamines can cross the blood-brain barrier and affect histamine receptors in the brain, which can cause sleepiness. Newer, less-sedating antihistamines are generally less likely to make you drowsy, although sleepiness can still occur with some products.3

How Do Antihistamines Work?

Antihistamines generally work by blocking the action of histamine at certain receptors after histamine has already been released.3

What Does “Non-Drowsy” Mean?

“Non-drowsy” does not describe one single type of hayfever product. Some newer antihistamines are considered less sedating or non-sedating, while other products use different approaches.3

BreathMor® is non-drowsy and contains no antihistamines, steroids or corticosteroids. It works earlier in the allergic response at the mast cell level, helping to reduce histamine release before symptoms take hold.*

Hayfever Symptoms can Be Managed?

How Can Hayfever Symptoms Be Managed?

Hayfever management often involves a combination of reducing exposure to triggers and choosing options suited to the symptoms you experience.23

Simple steps such as checking pollen forecasts, keeping windows closed on high-pollen days and showering after spending time outdoors may help reduce pollen exposure.2 Common symptom-relief options can also include antihistamines, intranasal corticosteroid sprays, saline nasal sprays and eye drops.23

BreathMor® is a clinically trialled* nasal spray containing a naturally derived active ingredient from Cinnamomum verum (Cinnamon) stem bark extract. It works earlier in the allergic response at the mast cell level, helping to reduce histamine release before symptoms such as nasal itching, sneezing and itchy eyes take hold, and helps to provide temporary relief from seasonal hayfever symptoms.*

Important: ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Adults only. If symptoms persist, talk to your health professional. Contains Sulfites (Sodium bisulfite).

What Should You Remember About Histamine and Hayfever?

What Should You Remember About Histamine and Hayfever?

Histamine is a normal chemical with several jobs in the body. During hayfever, however, allergens such as pollen can activate mast cells, leading to histamine release and symptoms such as sneezing, congestion, a runny nose and itchy eyes.24

Understanding this process also makes it easier to see why different hayfever options work in different ways. Antihistamines generally act after histamine has been released.3 BreathMor® works earlier in the allergic response at the mast cell level, helping to reduce histamine release before symptoms such as nasal itching, sneezing and itchy eyes take hold.*

Important: ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Adults only. If symptoms persist, talk to your health professional. Contains Sulfites (Sodium bisulfite).

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FAQs

What is histamine in simple terms?

Histamine is a natural chemical made by the body. It is involved in immune responses, digestion and wakefulness, and during an allergic response it can contribute to familiar allergy symptoms.4

Why does pollen cause histamine release?

In people with a pollen allergy, the immune system reacts to pollen and activates mast cells. These cells then release histamine and other inflammatory chemicals.24

Is histamine intolerance the same as hayfever?

No. Hayfever is an allergic response to environmental allergens. Histamine intolerance is a separate and still-debated concept relating to how the body processes histamine.25

Why do some antihistamines make you sleepy?

Some older antihistamines can enter the brain and interfere with histamine's role in maintaining alertness, which can cause drowsiness.3

How is BreathMor® different from an antihistamine?

Antihistamines generally block the effects of histamine after it has been released.3 BreathMor® does not contain antihistamines. It works earlier in the allergic response at the mast cell level, helping to reduce histamine release before symptoms such as nasal itching, sneezing and itchy eyes take hold.*

Important: ALWAYS READ THE LABEL AND FOLLOW THE DIRECTIONS FOR USE. Adults only. If symptoms persist, talk to your health professional. Contains Sulfites (Sodium bisulfite).

References

  1. 1. Australasian Society of Clinical Immunology and Allergy (ASCIA). Thunderstorm Asthma. https://www.allergy.org.au/patients/asthma-and-allergy/thunderstorm-asthma
  2. 2. Better Health Channel. Pollen Allergies. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/pollen-allergies
  3. 3. Healthdirect Australia. Antihistamines. https://www.healthdirect.gov.au/antihistamines
  4. 4. Frontiers in Immunology. The Role of Histamine and Histamine Receptors in Mast Cell-Mediated Allergy and Inflammation. https://pmc.ncbi.nlm.nih.gov/articles/PMC6099187/
  5. 5. Nutrients. Histamine Intolerance: Symptoms, Diagnosis, and Beyond. https://pmc.ncbi.nlm.nih.gov/articles/PMC11054089/

* Steels E, Steels E, Deshpande P, Thakurdesai P, Dighe S, Collet T. A randomized, double-blind placebo-controlled study of intranasal standardized cinnamon bark extract for seasonal allergic rhinitis. Complement Ther Med. 2019;47:102198.

Walanj A, Walanj S, Mohan V, Thakurdesai PA. Efficacy and safety of intranasal cinnamon bark extract in seasonal allergic rhinitis patients: a double-blind placebo-controlled pilot study. J Herb Med. 2014;4:37–47.

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