Courgette, or zucchini as it is known in the USA very rarely causes food allergies.
None of the allergens in courgette have been recognised by the World Health Organisation, but it thought that the allergen responsible for causing allergic reactions are plant profilins.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Courgette.php
The allergy resources page for courgette covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with courgette.
There is also regularly updated links to useful websites specifically for courgette allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.