Patch testing using chives can cause false-positive reactions because of diallyl disulfide which is found in the garlic bulb. This chemical acts as an irritant on the skin. Diallyl disulfide is used as a garlic flavouring in food and garlic oil.
An allergy to chives after ingestion is more commonly linked to Non-IgE allergy than a true IgE allergy. It is important if you think you are allergic to complete a food diary to ensure you are not eliminating large groups of food unnecessarily. There are tips on how to make a Food Diary here.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Chive.php
The allergy resources page for chives covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with chives.
There is also regularly updated links to useful websites specifically for chive 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.