You probably don't use OTC medications every day, so that jumbo bottle of pain reliever from the big-box store might expire before you can finish it. Choose a regular-size bottle of a generic brand at your local drugstore or supermarket. Don't miss these other things you should never buy at Costco.
Skip: Cleaning Supplies
Liquid cleaners typically lose some effectiveness after six months to a year (certain powders may have an indefinite shelf life if stored in a cool, dry place). Unless you have a large family, purchase household supplies like window cleaner, dish detergent, laundry soap, and bleach in regular-size containers at retail stores.
Skip: Paper Goods
Common household items go on sale so often that supermarket discounts may be deeper than big-box store price cuts. Pairing store sales with manufacturer coupons can dramatically shrink your bill.
6 Things to Absolutely Always Buy at Big-Box Stores (and 4 to Get at Retail), Source:https://www.rd.com/advice/saving-money/what-to-buy-at-big-box-stores/