All products can not be exchanged or refunded after they are opened. Even if the skin is affected by allergies, it can not be exchanged, refunded or compensated.
Allergy is an abnormal reaction that is caused by individual ingredients, so it is impossible to prevent allergic reactions from the seller's perspective.
If you are allergic to certain ingredients, make sure to check the cosmetics before using them. If the product does not have any opening stickers, the delivery date will be considered the opening date.