Allergic rhinitis Dr Adrian Morris Perennial allergic rhinitis is usually triggered by indoor allergens. It's similar to hay fever - the allergen causes inflammation and irritation of the delicate linings in the nose and eyes - but blockage is more of a problem than sneezing.

In this article

What causes it? What are the symptoms?

What's the treatment? Can it be prevented?

More and more people are developing allergic rhinitis because pets and central heating in winter encourage the growth of house dust mites. As a consequence, many people have symptoms all year round, while others have winter seasonal symptoms. As with asthma and eczema, it can run in atopic families.

Perennial allergic rhinitis starts in early childhood and occurs all year round. It's caused by allergy to the aerosolised droppings (faeces) of house dust mites and pet skin flakes (dander). Occasionally, indoor mould spores and, in rare cases, food allergy can be causes.

The following symptoms can be observed:

• Symptoms of a 'permanent cold'
• Blocked stuffy nose
• Headaches and earache
• Constant sore throats and postnasal drip
• Sleep disturbances and snoring
• Loss of taste and smell
• Poor concentration

Eye symptoms are uncommon.

Low-dose steroid nasal sprays and nose drops are the most effective treatment, but need to be used continuously on a daily basis throughout the year (unlike in hay fever, when the treatment is only necessary during the pollen season).

Decongestant tablets and sprays will help relieve a stuffy, blocked nose with catarrh, but can cause rebound blocking and should be used for short periods only .

Antihistamine medication may help, but it's more effective for hay fever. Low-dose steroid nasal sprays are more effective in perennial allergic rhinitis. An ipratropium nasal spray effectively treats the constantly 'dripping' nose seen in vasometer rhinitis.

Desensitisation immunotherapy, when available, might be considered in severe house dust mite allergic rhinitis. However, it is less effective than grass pollen desensitisation.

The only way to prevent perennial allergic rhinitis is to avoid the allergen that causes it, so allergy testing is important to identify the exact indoor allergen that provokes the allergy.

House dust mite eradication measures can help if special attention is paid to the bedroom:

• Synthetic pillows and duvets are better than feather fills
• Old mattresses harbour up to 10,000 house dust mites, so use mite impermeable barrier mattress covers
• Wash pillow cases and covers at 60°C
• Use a vacuum cleaner fitted with a HEPA filter
• Choose hardwood and laminate flooring, not heavy pile carpets
• Discourage soft toys and clutter
• Regularly air the bedroom to reduce humidity

For severe pet allergies, it's best to remove the pet from the home permanently

For severe pet allergies, it's best to remove the pet from the home permanently. Cat allergen spreads in the air throughout the home, even if the cat is restricted to specific areas.

Although short-haired and female pets carry less dander on their fur, any furry pets can trigger allergies, including rabbits, guinea pigs, hamsters, gerbils and mice.

This article was last medically reviewed by Dr Adrian Morris in September 2007.
First published in September 1999.