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Allergic rhinitis

Page last reviewed: 13/07/2011

Allergic rhinitis is a condition in which an allergen (something that causes an allergic reaction) makes the inside of your nose swell or become inflamed. This can cause cold-like symptoms, such as sneezing, itchiness and a blocked or runny nose.

Allergic rhinitis is one of the most common conditions in Ireland. Studies estimate that more than 30% of people experience the condition at some point in their life.

Hay fever is a type of allergic rhinitis that is caused by pollen. Allergic rhinitis may also be caused by other allergens, such as house dust mites or animal fur. See Allergic rhinitis - causes for more information.

Some people only experience allergic rhinitis for a few weeks or months at a time because they are sensitive to allergens (such as tree or grass pollen) that are only produced at certain times of the year. Others experience the condition all year round, because they are sensitive to non-seasonal allergens, such as house dust mite.


Allergic rhinitis is not usually harmful, but the symptoms can be irritating and affect your quality of life. Identifying the allergen that causes your rhinitis and, if possible, avoiding it is an important first step in managing the condition effectively.

Once diagnosed, mild cases of allergic rhinitis can usually be treated using over-the-counter medicines. However, more serious cases may require treatment with a corticosteroid nasal spray or antihistamines prescribed by a GP. See Allergic rhinitis - treatment for more information.

Non-allergic rhinitis

Not all types of rhinitis are caused by an allergic reaction. For example, some cases are caused by:

  • an infection such as the common cold
  • oversensitive blood vessels in the nose
  • overuse of nasal decongestants

For more information, see the Health A-Z topic on Non-allergic rhinitis.

Page last reviewed: 13/07/2011

The common symptoms of allergic rhinitis include:

  • sneezing
  • runny nose
  • itchy nose
  • blocked nose
  • many people will also have itchy eyes or throat

The symptoms of allergic rhinitis normally begin soon after exposure to an allergen. Some people only experience allergic rhinitis for a few months at a time because they are sensitive to allergens (such as tree or grass pollen) that are only produced at certain times of the year.

Others experience the condition all year round, because they are sensitive to non-seasonal allergens, such as house dust mite.

Most people with allergic rhinitis experience mild symptoms that can be easily and effectively treated. However, for some, the symptoms can be more severe and persistent, causing problems with sleep and interfering with everyday life.

Page last reviewed: 13/07/2011

Allergic rhinitis is caused by an oversensitive immune system (the body's natural defence system against infection) reacting to allergens, such as pollen, as if they are harmful. The immune system reacts by producing antibodies to fight off the allergen. Antibodies are special proteins contained in blood that are normally made by the immune system to fight off viruses and infections.

Allergic reactions do not happen the first time you come into contact with an allergen. The immune system has to recognise and memorise the allergen before making antibodies against it (a process known as sensitisation). The time taken to become sensitised to an allergen varies from days to years.

Once you have developed sensitivity to an allergen, whenever particles of the allergen come into contact with the inside of your nose and throat, antibodies called immunoglobulin E (IgE) are released. These cause blood cells to release chemicals (including histamine), which together cause the symptoms of allergic rhinitis.

The chemical histamine causes most of the symptoms that occur in allergic rhinitis, such as:

  • swelling of the mucus membrane (the inside layer of your nose), which blocks the airway and causes congestion
  • the production of excess mucus, which occurs as a result of the swelling and causes a runny nose and sneezing

Common allergens

Allergic rhinitis is triggered by breathing in tiny particles of allergens. The most common airborne allergens that cause rhinitis are: 

  • house dust mites (tiny insects that feed on the dead flakes of human skin). They can be found in mattresses, carpets, soft furniture, pillows and beds. Rhinitis is not caused by the dust mites themselves, but by a chemical found in their excrement. They are present all year round, though their numbers tend to peak during spring and autumn
  • tree and grass pollen. Tiny particles of pollen produced by trees and grasses can cause allergic rhinitis. Most trees pollinate between early to mid spring. Grasses pollinate at the end of spring and beginning of summer 
  • animals. Many people are allergic to animals and pets, such as cats and dogs, but animal fur does not cause the allergic reaction. It is caused by the flakes of dead animal skin, their urine and saliva. Dogs and cats are the most common culprits, although some people are affected by horses, cattle, rabbits and rodents, such as guinea pigs and hamsters
  • work-related allergens. Some people are affected by allergens that are present in their work environment, such as wood dust, flour dust or latex

Who is at risk?

It is not fully understood why some people develop oversensitivity to allergens.

However, some people are more likely to develop an allergy because it runs in their family. If this is the case, you are said to be atopic or to have atopy. People who are atopic are more likely to develop allergies because their body produces more IgE antibodies than normal.

Environmental factors also play a part in the development of allergic disorders such as rhinitis. The exact role of the environment is unknown, but studies have shown that a number of factors seem to increase the chance of a child developing atopy, such as:

  • growing up in a house with smokers
  • exposure to dust mites
  • exposure to pets
  • using antibiotics

Page last reviewed: 13/07/2011

Your GP can usually diagnose allergic rhinitis by asking about your symptoms and your personal and family medical history. They will also ask about any triggers that seem to cause a reaction, and whether it happens at a particular place or time.

Your GP may examine the inside of your nose to check for nasal polyps. Nasal polyps are fleshy swellings that grow from the lining of your nose or your sinuses (the small cavities inside your nose). They can be caused by the inflammation (swelling) that results from allergic rhinitis.

You may be asked a couple of questions to rule out other possible causes of rhinitis, such as an infection or exposure to chemicals.

Diagnosis of allergic rhinitis is normally confirmed at the beginning of treatment. If you respond well to antihistamines, it is almost certain that your rhinitis is caused by an allergy. If the exact cause of your allergic rhinitis is uncertain, you may be referred for allergy testing.

Allergy testing

Two tests that may be carried out are:

  • skin prick test. This is usually the first test to be carried out when trying to determine which allergen is causing your allergic rhinitis. The allergens are placed onto your arm and introduced into the skin by pricking it with a short pin. If you are allergic to the substance, your skin will become itchy, red and swollen
  • blood test. This is used to measure the amount of immunoglobulin E (IgE) antibody in your blood that has been produced by your immune system in response to a suspected allergen

The use of commercial allergy testing kits is not recommended. The testing is often of a lower standard than that provided by the health services. Also, it is important that the results of the test are interpreted by a qualified professional who has detailed knowledge of your symptoms and medical history.

When to seek medical advice

See your GP if your allergic rhinitis is:

  • disrupting your sleep
  • impairing your ability to carry out everyday activities
  • adversely affecting your performance at work or school
  • not responding to over-the-counter medications

Page last reviewed: 13/07/2011

If the symptoms of allergic rhinitis are mild, you should be able to treat the condition yourself by:

  • avoiding the particular allergen that triggers the condition (see Allergic rhinitis - prevention for more advice)
  • taking over-the-counter medications such as antihistamines , steroid nasal sprays and decongestants to relieve congestion and a runny nose (see below)
  • nasal douching (rinsing your nasal passages regularly with salt water to keep your nose free of irritants)

If your symptoms are more severe, affecting your quality of life, and self-help measures are not effective, see your GP. The treatment options are described below.


Medication will not cure your allergy, but it can be used to treat the common symptoms of an allergy, such as a runny nose, itchy mouth and sneezing.

If your symptoms are caused by seasonal allergens, such as pollen, you should be able to stop taking your medication after the risk of being exposed to the allergen has passed. However, if your allergic rhinitis is caused by non-seasonal allergies, such as dust mites, you may require ongoing treatment.

Treatment for allergic rhinitis is generally the same for adults and children. If you are pregnant, you can take some antihistamines and corticosteroids. It is usually recommended that you use a nasal spray rather than taking tablets to minimise any risk to your unborn baby.

See your GP if your symptoms do not respond to medication after two weeks.


Antihistamines relieve symptoms of allergic rhinitis by blocking the action of the chemical histamine, which the body releases when it thinks it is under attack from an allergen. Antihistamine tablets are available over-the-counter (OTC) without prescription from your pharmacist, but antihistamine nasal sprays are only available with a prescription.

Antihistamines can occasionally cause drowsiness, so if you are taking them for the first time, see how you react to the medication before driving or operating heavy machinery. Antihistamines can cause drowsiness if you drink alcohol while taking them.


If your symptoms are frequent or persistent and you have a nasal blockage or nasal polyps, your GP may recommend that you use a nasal spray or drops containing corticosteroids.

Corticosteroids help reduce inflammation (swelling). They take longer to work than antihistamines, but their effects last longer.

Side effects from inhaled corticosteroids are rare, but can include nasal dryness and irritation, and nosebleeds.

If you have a particularly severe bout of symptoms and need rapid relief, your doctor may prescribe a short course of corticosteroid tablets for 5 to 10 days.

Long-lasting steroid injections are a treatment of last resort and are only recommended in exceptional circumstances due to the significant risks associated with their use, which can include weight gain, diabetes, osteoporosis, high blood pressure, and increased risk of serious infections.

Nasal decongestants

Decongestants are usually available over the counter and can help relieve a blocked nose. They can be taken as tablets, capsules, nasal sprays or liquids.

Nasal decongestants should not be used to treat allergic rhinitis for more than five to seven days. Using them for longer can make your congestion worse.

If you are taking a type of antidepressant known as a monoamine oxidase inhibitor (MAOI), do not use nasal decongestants.

Add-on treatments

If your allergic rhinitis does not respond to the above medications, there are several medicines that your GP can 'add on' to your original treatment. Your GP may suggest you try any of the following:

  • increasing the dose of your corticosteroid nasal spray
  • using a short-term course of a decongestant nasal spray to take with your other medication
  • combining the use of antihistamine tablets with corticosteroid nasal sprays and possibly decongestants
  • using an inhaler containing a medicine called ipratropium, which will help reduce excessive nasal discharge

If you do not respond to the add-on treatments, you will be referred to a specialist for further assessment and treatment.

Hyposensitisation (immunotherapy)

Another form of treatment for some allergies is hyposensitisation, also known as immunotherapy. It is only suitable for people with certain types of allergies, such as hay fever, and is only usually considered if your allergy is severe.

Hyposensitisation gradually introduces more and more of the allergen into your body to make it less sensitive to the allergen.

The allergen is usually injected under the skin of your upper arm. In the initial stages of treatment, you will be given injections at intervals of a week or less, while the allergen doses are gradually increased.

When you reach the 'maintenance dose' (a dose that is effective in reducing your normal allergic reaction), you will need to continue to have injections of this dose every few weeks for at least two years. This type of treatment must only be carried out under the close supervision of a doctor, because there is a risk it may cause a serious allergic reaction.

Immunotherapy for grass pollen using an oral medicine is also available for those with severe symptoms

Page last reviewed: 13/07/2011

Nasal polyps

Nasal polyps are fleshy swellings that grow from the lining of your nose or your sinuses (the small cavities inside your nose). They are the result of inflammation (swelling) of the membranes of the nose, and are sometimes caused by rhinitis.

A nasal polyp is shaped like a teardrop when it is growing and looks like a grape on a stem when fully grown. Nasal polyps may be yellowish, grey or pink in colour and vary in size. They can either grow on their own or in clusters, and usually affect both nostrils.

If they grow large enough or if they grow in clusters, nasal polyps can:

  • interfere with your breathing
  • reduce your sense of smell
  • block your sinuses, leading to sinusitis (see below)

Smaller polyps can be shrunk using corticosteroid nasal sprays so that they do not cause any obstructions in your nose. Large polyps may need to be surgically removed.

See the Health A-Z topic on for information on the causes and possible treatments.Nasal polyps


A common complication of rhinitis is sinusitis. This is inflammation or infection of your sinuses.

Usually, if your sinuses become filled with mucus, the fluid drains away. However, if the fluid cannot drain away, for example as the result of a blockage, it can become infected with bacteria.

Sinusitis is a common problem for people with rhinitis because an excess of mucus or nasal polyps can stop the sinuses from draining properly.

Common symptoms of sinusitis include:

  • pain and tenderness of the infected sinus. You may experience a throbbing pain in your sinuses and toothache or pain in your jaw when you eat
  • a blocked or runny nose. Your nose may produce a greenish or yellowish mucus. If your nose becomes blocked with mucus, any pain and tenderness in the affected area may become worse
  • high temperature over 38C (100.4F)

The symptoms of sinusitis can be relieved using over-the-counter painkillers, such as paracetamol, ibuprofen or aspirin. These will relieve a headache, high temperature and any pain or tenderness that you have around the infected area.

Children under 16 years of age should not take aspirin. Ibuprofen is not recommended for asthmatics or people who have (or have had) stomach conditions, such as ulcers. Speak to your GP or pharmacist if you are unsure whether you should take it.

Antibiotics may be recommended if you develop a secondary infection in your sinuses. If sinusitis remains a long-term problem (chronic sinusitis), you may require surgery to improve the drainage of your sinuses.

See the Health A-Z topic on Sinusitis for further information on the causes and possible treatments.

Page last reviewed: 13/07/2011

The best way to prevent an allergic reaction is to avoid the allergen that causes it. However, this is not always easy. Allergens, such as dust mites, can be hard to spot and can breed in even the cleanest house. It can also sometimes be difficult to avoid pets, particularly if they belong to friends and family.

Follow the advice below to avoid some of the most common allergens.

House dust mites

Dust mites are one of the biggest causes of allergies. Dust mites are microscopic insects that breed in household dust. Below are a number of ways that you can limit the amount of mites in your house:

  • Choose wood or hard vinyl floor coverings instead of a carpet.
  • Fit roller blinds that can be easily wiped clean.
  • Clean cushions, soft toys, curtains and upholstered furniture regularly, either by washing or vacuuming.
  • Use synthetic pillows and acrylic duvets instead of woolen blankets or feather bedding.
  • Use a vacuum cleaner fitted with a HEPA (high efficiency particulate air) filter, because it can remove more dust than ordinary vacuum cleaners.
  • Wipe surfaces with a damp, clean cloth as dry dusting can spread the allergens further.

Concentrate your efforts on controlling dust mites in the areas of your home where you spend the most time, such as the bedroom and living room.


It is not the pet fur that causes an allergic reaction, but exposure to flakes of their dead skin, saliva and dried urine.

If you cannot permanently remove a pet from the house, you may find the following tips useful:

  • Keep pets outside as much as possible or limit them to one room, preferably one without carpet.
  • Do not allow pets in bedrooms.
  • Wash pets at least one a fortnight.
  • Groom dogs regularly outside.
  • Wash all bedding and soft furnishings your pet has been on.

If you are visiting a friend or relative with a pet, ask them not to dust or vacuum on the day you are visiting, as this will stir up the allergens into the air. Taking an antihistamine medicine one hour before entering a pet-inhabited house can help reduce symptoms.


Different plants and trees pollinate at different times of the year, so when you get allergic rhinitis will depend on what sort of pollen(s) you are allergic to. Typically, people are affected during the spring and summer months because this is the time of year when most trees and plants pollinate. To avoid exposure to pollen, you may find the following tips useful:

  • Check weather reports for the pollen count and stay indoors when it is high.
  • Avoid line-drying clothes and bedding when the pollen count is high.
  • Wear wraparound sunglasses to protect your eyes from pollen.
  • Keep doors and windows shut during mid-morning and early evening, when there is most pollen in the air.
  • Shower, wash your hair and change your clothes after being outside.
  • Avoid grassy areas, such as parks and fields.
  • Get someone else to cut the grass for you if you have a lawn.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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