You may be wrong on this

If you used the whitening formula for one year and switched to other products, your allergenic reaction is from other products. The time to indue the T cell to response to an allergen is far less than a year. In clinic studies, the induce time is less than 6 weeks. One the mechanism is on you will response to the product you apply. In another word, you will have far less than a year to show sensitization. If you had allergenic reaction to other brands after the Shiseido, you only can say other brands have the allergens you are sensitive too. If Shiseido products indued you, they must have the same allergens in the products. Why did you have reaction when you were using their products, because their formulation skills are far better than other cheap brands. Every products have allergens you may response too, the key is how to formulate them to cause less reactions. Only large companies test their formulas for irritation and sensitization before launch. Not all the expensive brands do, because some brands are expensive but the company is very small. They are not regulated good enough.