It is highly unlikely that you will experience an allergic reaction as our ingredients and formulations are designed to create a surge of hydration to purge the skin of micro-bacteria while also being anti-inflammatory and skin-building in nature. We do not have retinols or other acids (such as glycolic or lactic) in our products whatsoever. But if you experience an allergic reaction, please immediately stop use contact a medical professional. As a part of your skin care regimen we advise the below for best skin performance prior to applying products from Caire's skin care store:Apply Mask 1-3 times per week for an ultra hydrating boost to your mature and aging skinCleanse skin with a cleanser of your choice (for drier skin, Co-Founder Lorrie uses an oil based cleanser and during the summer when her skin is more hydrated, she uses a enzymatic cleanser to help purge the pores better)Apply a toner with natural botanicals that replenishing to your skin to help balance your skin's PHApply the Caire serum, allow to dry well and then you can apply other serums or moisturizers.  Caire Founder's Observation: you may notice that over time with use of the Caire serum that your skin may no longer need a moisturizer.Apply other serums (eg. Vitamin C, Retinols as advised by your doctor, etc.) and moisturizers