Hypoallergenic mattresses - or, more simply, "anti-allergy" mattresses - are designed to resist the accumulation of allergens and facilitate a comfortable night's sleep for those who need them.
How they work
There is no prescribed material for a hypoallergenic mattress, but generally they are layered with non-sticky fabrics like silk and latex. The purported advantage of this is that these materials are less likely to attract dust mites (which are a huge no-no if you have sensitive allergies).
These types of mattresses are also better equipped to absorb moisture, which can help to keep you dry on a sticky summer night (again, this makes you less likely to attract pollutants in the atmosphere). The caveat to this is that you also need to have matching sheets, duvet and pillow covers in order to truly reap the benefits.
Try to avoid cotton
While it's difficult to completely take a staple material like this out of the equation completely, studies have shown sensitive allergies can be affected by cotton due to the chemical treatment process it undergoes before it's ready for the consumer.
Let your bed breathe
It's a good idea to look for the more porous materials that "breathe" well; this helps to ventilate your sleeping area and prevent the accumulation of sticky moisture.
Matching bedding is a must
It's no good having a hypoallergenic mattress if you don't also take the time to pick out some equally resistant sheets, duvet covers and (perhaps most importantly) pillow cases.
Old-fashioned cleaning helps too
Remember that, although an anti-allergy mattress can help to keep pollutants away, there is no substitute for elbow grease and a watchful eye. This means regularly changing the sheets and ensuring you keep grubby hands (and pets) away from your sleeping area.
Buying your mattress
Unfortunately, there aren't many companies which specialise in selling anti-allergy mattresses. On top of this, it can often be difficult to identify which materials are affecting your allergies - this means there is a lot of trial and error involved.
Major retailers like Dreams, SilentNight, Ikea stock mattresses of all materials, but remember that they often place emphasis on comfort and luxury rather than health. "Hypoallergenic" or "anti-allergy" are not always listed among their categories, so it's a good idea to go the store itself rather than shop online. That way you can get a feel for the mattress and ask around if you need any assistance.
For expert advice, it's also worth consulting your local GP (don't be afraid to go in for something like this; it's what they are there for). They may be able to figure out what is triggering your allergies and give you some advice on what to avoid when shopping for your new mattress.