Hay Fever (Allergic Rhinitis): Symptoms, Causes, Treatment and Prevention

Published: 23 July 2026

🩺 Medically reviewed by the Health Decoded Guide Editorial Team· Last reviewed: July 2026

🔍 Quick Summary

Hay fever (allergic rhinitis) is an allergic reaction that affects the nose and eyes when the immune system overreacts to harmless substances such as pollen, dust mites or animal dander.

It can affect both children and adults and may occur during certain seasons or throughout the year.

Although it is not usually dangerous, symptoms can interfere with sleep, work, school and daily activities if left untreated.

1️⃣ Introduction

Hay fever, also called allergic rhinitis, is a common allergy that causes inflammation inside the nose after exposure to allergens.

Depending on the trigger, symptoms may occur only during certain seasons or throughout the year.

• affects both children and adults
• not caused by bacteria or viruses
• cannot be spread from one person to another

👉 Hay fever is caused by the immune system reacting to harmless substances as though they were dangerous.

2️⃣ How it happens

When a person with allergies breathes in an allergen:

• the immune system mistakenly identifies it as harmful
• antibodies trigger the release of histamine and other chemicals
• these chemicals cause swelling, itching and increased mucus production

👉 Histamine is responsible for many of the classic allergy symptoms such as sneezing, itching and a runny nose.

3️⃣ Types

Seasonal allergic rhinitis

• triggered by pollen from trees, grasses or weeds
• symptoms occur during specific times of the year

Perennial allergic rhinitis

• symptoms occur throughout the year
• commonly caused by dust mites, mould, cockroaches or pet dander

👉 Identifying the trigger can help reduce symptoms and improve treatment.

4️⃣ Common causes

Outdoor allergens

• tree pollen
• grass pollen
• weed pollen

Indoor allergens

• dust mites
• mould
• pet dander
• cockroach allergens

5️⃣ Symptom explanation

• frequent sneezing
• runny or blocked nose
• itchy nose, throat or eyes
• watery or red eyes
• reduced sense of smell

👉 These symptoms occur because allergy chemicals cause inflammation and increased mucus production in the nose and eyes.

6️⃣ Associated symptoms

• postnasal drip
• cough, especially at night
• headaches or facial pressure
• poor sleep due to nasal blockage
• tiredness and reduced concentration

👉 Poor sleep is one reason hay fever can affect school performance, work productivity and overall quality of life.

7️⃣ When it becomes dangerous 🚨

Seek medical attention if:

• breathing becomes difficult or wheezing develops
• facial pain, fever or thick green nasal discharge suggests a sinus infection
• symptoms remain severe despite treatment
• symptoms significantly affect sleep or daily activities

👉 These may indicate:

• asthma or another allergic condition
• a complication such as sinusitis that needs further assessment

8️⃣ Management and treatment

• avoid known allergy triggers whenever possible
• keep windows closed during high pollen seasons
• shower and change clothes after spending time outdoors
• use saline nasal rinses to help clear allergens
• antihistamines, nasal steroid sprays or other medicines may be recommended by a healthcare professional

👉 Effective treatment often combines avoiding triggers with appropriate medication.

9️⃣ Diagnosis

Diagnosis is usually based on:

• your symptoms and when they occur
• physical examination
• allergy testing when the trigger is unclear

👉 Knowing exactly what causes your allergies can help guide treatment and prevention.