Before using any products you need to make sure that you have studies both its effects and also its side effects properly. Many products have harmful side effects but they do not state it explicitly. Do your research properly.
One thing which has side effects but no benefit is the preservative which is found in so many anti aging serums and creams.
Preservatives are added purely for the benefit of the seller and not the buyer. The objective of the preservative in anti aging serum is to increase the shelf life of the product.
Stop putting preservatives on your skin, they might have many side effects you might not be aware of. There are few zero preservative products available, check them out and make an informed purchasing decision.