Some skins are sensitive, and applying even natural products can lead to rashes. The cause could be genetic or hormonal, or sustained and long-term exposure to chemicals in cosmetics, or in food or the environment.
People with sensitive skins should take care before applying anything on their skin - they should check the product by applying in minute quantities in the inside of their elbow or the wrist.
We have a host of products that are appropriate for sensitive skins. Even for these, the amount/frequency of use should be carefully monitored.