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All about Indoor Allergies

Last updated on 20th December 2023

The UK has a very high prevalence rate of allergic conditions, reportedly one of the highest in the world according to Allergy UK. Indeed, an astonishing 44% of adults in the UK have at least one allergy, with the number of people affected growing each year. Around half of the people who have an allergy also have at least one more (48%).

Nearly a third of those affected have had to make changes to the way they live their lives due to their allergy. This includes 11% who say they must keep their home extra clean as well as 11% saying they need to use special bedding. Such changes are particularly prevalent among those with indoor allergies.

What is an indoor allergy?

Indoor allergies, as you may expect, are those that are most apparent when someone is inside their own home or when visiting other people’s homes. They step through the door and within minutes they have a scratchy throat, watery or itchy eyes, nasal congestion, a runny nose, or even itchy skin.

Indoor allergies are not particularly seasonal, unlike allergies that are linked with pollen. Sometimes they may be less obvious in the summer months when the air is dryer and doors and windows are open a lot, but generally, they’re always there. Because they’re an allergy that’s triggered inside people’s homes, it means they’re more difficult to avoid than some other allergies.

What are the types of indoor allergies?

Indoor allergies usually have a specific trigger but it can be difficult for a person to work out what that trigger is initially. Common allergens that are found in the home include dust mites, mould, pet dander and sometimes even insects like cockroaches!

The problem with indoor allergies is that every home and many indoor public spaces like hotels, libraries or restaurants all harbour potential allergens. It is very difficult to eliminate allergens even within the home.

Dust Mite Allergy

An allergy to dust mites is one of the most common indoor allergies. Dust mites are tiny creatures that are only about a quarter of a millimetre in length. Dust mites survive by eating the dead flakes of human skin that have been partially digested by mould. They thrive in warm, moist environments – i.e., the vast majority of homes in the UK. Dust mites are found around the home within carpets, soft furnishings, clothing and bedding.

For those with a house dust mite allergy, it’s not always the mites themselves that cause the reaction. Often, it’s the mites’ droppings that trigger the reaction. Every dust mite produces around 20 droppings each day with the droppings causing reactions well after the mite has died.

What can people do if they have a dust mite allergy?

There are several ways of trying to keep dust mites under control in the home. A combination of strategies is best to tackle these prevalent little arthropods.

  • Use anti-allergy bedding, mattress protectors, duvets and pillows.
    Exposure to dust mites and their droppings is often more significant when someone is in bed. Taking precautions to reduce dust mites in bedding and the bedroom is one way that many people try and mitigate their dust mite allergy. Using allergy-proof sheets and bedding and changing the bedding regularly can help.
  • Wash blankets, covers, soft toys and soft furnishings regularly.
    Washing sheets and other covers can help eliminate and reduce the droppings and the mites themselves. Washing at 60°C is recommended to kill the mites. The allergen is dissolved at lower temperatures but the mites survive and can continue to produce droppings even after you’ve put clean sheets on your bed.
  • Think about alternative flooring.
    Carpets are perfect environments for dust mites and their droppings. Changing flooring to tiles or wooden flooring will help to eliminate dust mites and droppings especially if you vacuum and clean regularly.
  • Use steam cleaners and high-powered vacuum cleaners.
    If you can’t remove carpets, cleaning them regularly with a steamer or a high-filtration vacuum will help to eliminate mites and their droppings better than a standard vacuum cleaner.
  • Wipe surfaces with a damp cloth regularly.
    Damp wiping of windowsills, bannisters and the tops of units or cupboards will remove mites, dust and droppings.
  • Use washable curtains and wash them regularly.
  • Increase ventilation.
    Increasing ventilation will reduce the humidity in the rooms and therefore the mites will not be able to survive for as long. Use trickle vents and open windows where possible. You could also use a dehumidifier to keep humidity between 30% and 50%.
  • Do not sleep on the bottom bunk of a bunk bed.
    If you have a child who’s allergic to dust mites, don’t have them sleep on the bottom bunk below someone else. This will increase the likelihood of dust and dust mites falling on them whilst they sleep.
  • Apply an allergen barrier around the nostrils.
    Allergen barrier balms can trap or block allergens to reduce or prevent reactions. Barriers include petroleum jelly like Vaseline or specific allergy nasal sprays and eye drops.
Dust mite on bed

Animal Dander Allergy

Animal dander allergies are another common cause of indoor allergies. These occur when someone comes into contact with a pet’s fur, dander or saliva.

Allergies to animals include:

  • Cats.
  • Dogs.
  • Rabbits.
  • Rodents (including mice, hamsters and guinea pigs).
  • Birds.
  • Horses.
  • Reptiles (such as iguanas).
  • An allergy to pet bedding (shredded paper, straw or mould).

Of course, not all of these allergies are common and you wouldn’t particularly find someone with a horse allergy struggling in someone’s home! The most common indoor allergies are typically with cats and dogs, largely because these are the most common pets in our homes.

People are allergic to animals because the animals release a protein in the skin and saliva cells which are believed to be the cause. This protein is spread when pets groom themselves or when they moult their fur.

What can people do if they have an allergy to animal dander?

There are steps that people can take to reduce their reaction to animal dander or prevent it altogether. An allergy to animals is often one of the easier indoor allergies to manage unless of course you’re an animal lover and have pets!

  • Keep pets outside.
    This is a tricky one. But if you really can’t rehome your pets, keeping them outside as much as possible is one way you can reduce your exposure to the allergen. If you can’t keep the animals outside, try and keep them confined to one room within the home.
  • Do not let pets sleep on your beds or sofas.
    Animals should have their own beds to reduce them spreading their dander onto places where you sit and sleep.
  • Wash pet bedding regularly.
    Washing pet bedding will help to reduce the allergen. Use a hot wash to make sure that any allergen is fully destroyed. Clean any cages with hot water. Clean them outside if possible so that allergens are not spread further within the home.
  • Remove contaminated clothing before returning home.
    This one applies if someone in your home is allergic to horses (or other animals) that are not kept within the home. Taking off any clothing that has been contaminated and bagging it before bringing it home and washing it will help to reduce the allergen within the home.
  • Use an air purifier.
    Many people swear by using an air purifier to help eliminate pet allergens in the air.
  • Wash hands regularly.
    If you do have a pet, wash your hands regularly, particularly after stroking pets or handling their bedding.
Animal dander allergy is an indoor allergy

Mould Allergy

An allergy to mould is also a common indoor allergy. Mould and fungi grow within our homes and release spores that we inhale which then can cause an allergic reaction.

Spores are tiny particles that the moulds release. These spores make contact with people’s skin as well as the membranes inside their nose and lungs. Some well-known mould allergies have their own names such as ‘Sauna-taker’s lung’ and ‘Farmer’s lung’.

It is possible to be allergic to outdoor and indoor moulds. Moulds within the home cause reactions all year round. Common moulds include the black mould you’ll find on windowsills as well as others that grow on decaying food. The most common places within the home where mould is found are in damp, musty and moist areas such as in the bathroom, kitchen, cellar and garage.

What can people do if they have a mould allergy?

 There are several things that mould allergy sufferers can do to reduce their symptoms and their exposure to the allergen.

  • Ventilate the home well.
    Given that mould thrives in dampness, ventilating the home well will help reduce mould. You can do this by opening trickle vents on windows, opening windows, and also using a dehumidifier.
  • Wear a face mask.
    If you’re going to venture down into the cellar or the garage, wearing a face mask may help reduce the number of mould spores you inhale.
  • Clean damp spaces regularly.
    Kitchens and bathrooms should be cleaned regularly to reduce mould within these spaces. Bathrooms should be kept as dry as is reasonably possible to prevent the growth of mould.
  • Do not leave wet clothes hanging up to dry.
    It is better to line dry clothes or use a tumble dryer if you have a severe mould allergy.
  • Do not bring damp wood into the home.
    If you have an open fire or a log burner, try not to bring damp logs into your home. They will undoubtedly contain mould spores.
  • Reduce or remove house plants.
    As lovely as they are, house plants can harbour mould. Limit them and keep them in well-ventilated areas.
  • Clean out your fridge every week.
    Go through the drawers and make sure you throw out any dodgy-looking food. Mould thrives in the fridge!
Dehumidifier to reduce indoor allergy to mould

Cockroach Allergy

Perhaps not considered a common allergy in the UK, but a surprising number of people are allergic to cockroaches. The allergens are excreted by the cockroaches. Quite often, those with a cockroach allergy may also have a latex allergy as some species of cockroach have a protein called chitinase in them which is similar to those in latex.

Cockroaches are not all that common in UK homes as they usually prefer warmer climates. That said, they are sometimes found in the UK.

What can people do if they have a cockroach allergy?

Given that the UK’s climate is quite cool, cockroaches are not something that most of us have to worry about. But, if it is a worry, there are things that you can do to reduce your risk of exposure.

  • Keep rubbish bins secure with fixed lids.
  • Wash up dirty dishes quickly, including pet food bowls.
  • Clean any spills including water leaks as soon as possible.
  • Use traps or get in pest control if you’ve spotted cockroaches in your home.
  • Seal up any cracks in floors and walls to prevent any insects from entering.
  • Keep food stored in lidded containers that bugs cannot access.

All of the above will help you to keep cockroaches at bay.

Pest control to remove cockroaches

What causes an indoor allergy?

Indoor allergies are caused by allergens that are present within our homes and many indoor public spaces too. When a person with an indoor allergy comes into contact with an allergen, their immune system reacts to the perceived threat.

The immune system then releases certain chemicals to try and counteract the threat. One of the chemicals is histamine.

Histamine and other chemical substances in the body cause allergy symptoms to appear. Their eyes may water, their nose may run or they may start to itch or even cough. Antihistamine medications can help to alleviate the body’s reaction to the allergen.

No one knows why some people’s immune systems overreact to allergens but there are some arguments that there are some hereditary links. Indoor allergies are also particularly associated with other conditions such as asthma and eczema, which also have strong genetic links.

What are the signs and symptoms of an indoor allergy?

Those of us with an indoor allergy will be very familiar with the symptoms.

They include:

  • Runny nose.
  • Sneezing.
  • Nasal congestion.
  • Itchy throat.
  • Itchy eyes.
  • Skin rashes or hives.
  • Fatigue.
  • Cough.

For people with a severe allergy, there are some more worrying and troublesome symptoms:

  • Shortness of breath.
  • Wheezing.
  • Frequent, severe sinusitis.
  • Malaise.

Many of these symptoms are similar to those of other allergies or the common cold. However, the signs and symptoms of an indoor allergy are very much associated with being in your own home (or in other people’s) and typically endure the entire time you’re inside.

How is an indoor allergy diagnosed?

If someone is troubled by the signs and symptoms of an indoor allergy, they often visit their GP. The GP may prescribe medications such as antihistamines to see if they help to reduce the symptoms. If they do help, the GP can diagnose an indoor allergy, but it may not always be obvious what their allergen is.

As a result, some people with indoor allergies are referred to the hospital for allergy testing and sometimes for treatment. At the hospital, an immunologist performs tests that identify allergens. They can perform blood tests that check for IgE (immunoglobulin E) antibodies as well as skin prick tests where a small amount of an allergy is put into the skin to see if a reaction occurs.

When the immunologist has all of the results, they can diagnose a specific indoor allergy such as an allergy to house dust mites or a combination of allergies. From there, treatments and prevention are often the next step that is discussed.

How is an indoor allergy treated?

Indoor allergy treatment is often in combination with preventative measures such as those described earlier.

Common medications for indoor allergies include:

  • Cetirizine (Zyrtec/Piritieze) or other non-sedating antihistamines like Acrivastine, Fexofenadine (Allegra) and Loratadine (Claritin).
  • Chlorphenamine (Piriton) or other antihistamines that make you drowsy such as Cinnarizine, Diphenhydramine (Benadryl), Hydroxyzine and Promethazine.
  • Nasal steroids such as Flonase or Advair.
  • Nasal or oral decongestants such as Pseudoephedrine (Sudafed). These can be used for a few days if antihistamines aren’t working but shouldn’t be used on a long-term basis.
  • Leukotriene receptor antagonists like Montelukast (Singulair) are occasionally prescribed where no other treatments have worked. They do have adverse effects in some people such as psychiatric or neurological symptoms, so should always be taken with caution.

Unfortunately, for some people, medications such as those above are not as effective. If this is the case, an immunologist may recommend immunotherapy. This is often in the form of an injection therapy but sublingual medications (medicines placed under your tongue) have now been trialled too.

Immunotherapy exposes you to a tiny amount of an allergen over an extended period. This is in the hope that it will desensitise the immune system. Because of the risks, immunotherapy is always carried out under hospital supervision and is a big commitment.

Taking tablets to treat indoor allergy

How to manage an indoor allergy – asthma

Asthma associated with indoor allergies is trigged by the allergen and causes the immune system to go into overdrive. The allergen (such as the house dust mite) causes the immune system to respond by constricting the bronchi which, in turn, causes coughing, wheezing and other typical asthma symptoms.

Allergic asthma is often a distinct diagnosis of an allergy as the symptoms are specifically different. It is managed by avoiding triggers as well as preventative treatments and medications such as inhalers in addition to separate treatments when an attack occurs. These medications are often known as maintenance medication and rescue medication.

Allergy UK has a section on allergic asthma which may be useful if your allergies trigger an asthma attack. The Asthma & Lung UK page also has information on this topic.

Final thoughts on indoor allergies

Indoor allergies are persistent and annoying for sufferers. Thankfully, there are many measures you can take to prevent or reduce reactions as well as many available treatment options. If you need support for your indoor allergies, websites such as Allergy UK are a valuable source of information. They also have a helpline too.

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About the author

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Laura Allan

Laura is a former Modern Foreign Languages teacher who now works as a writer and translator. She is also acting Chair of Governors at her children’s primary school. Outside of work, Laura enjoys running and performing in amateur productions.

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