Allergy Testing

Skin testing

Skin testing is the best way to find out what, if anything, is causing a person's allergic problems. It involves putting a small drop of a solution containing allergens (for example rye grass, or dust mite) on the skin. The skin is then scratched and if you are allergic, a small hive comes up (like a mosquito bite). It is very safe if performed properly and not painful.

Skin testing provides more information than the blood test (RAST), and is more sensitive, occasionally someone can be negative to the blood test but does have an allergy confirmed on skin testing and vice versa.

It works very well for food allergies, particularly if they are immediate; hay fever; asthma; eczema and some drug allergies.

Your General Practitioner will be able to advise you as to whether you need these tests. The tests are done on the day you attend and we usually get a result within 10-15 minutes, except for penicillin and bee venom testing which takes up to 3 hours.

Patch testing

This is useful for patients with delayed reactions. For example, it can determine what chemicals you are allergic to. In general it is only used if you have skin reactions to certain chemicals, such as to jewellery, or hair dyes.

Because it is looking for a delayed reaction, the patch is usually applied on one day and then you need to return 2 days later to have it removed and again the following day to have your results read and interpreted.


Desensitisation is a treatment that "tricks", or "re-educates" the immune system to think that the allergen is a normal part of the environment (which it is!). It works better than nasal steroids and an antihistamine combined and is the only available treatment that can go close to curing an allergy.

It works exceptionally well for people with allergic rhinitis, but can also work for those with asthma and eczema. In children it can stop new allergies developing (ie if allergic to dust mite, it can stop you becoming allergic to cat etc). Even more importantly, it has also been shown to prevent the development of asthma in children.

Treatment involves either injections, or drops or tablets under the tongue (sublingual). Each person who has desensitisation needs to have a mix of allergens tailored to their individual needs. The tablets are often only available for single allergens.

Injection immunotherapy is given weekly for 15 weeks, then monthly for the next 3 years. It is a big time commitment, but worth it! It is generally given for 3 years total, but we should know if it is going to work within the first year. Injections have to be given at a doctor’s surgery and you must wait for 30 minutes after every injection which may make it somewhat inconvenient, but it is very effective.

Sublingual desensitisation (drops or tablets under the tongue) is new. It has been used widely in Europe for many years and is now available in Perth. This works the same as injections and needs to be taken for 3-4 years. It is very safe and more convenient because it can be given in your own home. There are only mild side effects such as itching in the mouth but there are no needles involved. It works very well for Spring pollens and for dust mite.