I can recommend Schwarkopf Igora Senea (Salon). This is the first professional colour range that is recommended by world dermatologists. Launched in May 2011, this product is ammonia and paraben free.
For first time colour application on virgin hair growth after treatment, please do not try colouring at home. Schwarzkopf Professional will give you salons stocking this product if you ring them on 01 4046424. Skin tests will apply.
From experience, health store products are unreliable and vary from product to product. Most still have some form of oxident. IMHO , Allergies are far more common with "organic type" colourants that in normal products as the ingredients are very intense. A professional Salon will always skin test.