Cream cheese is a dairy product often spread over bread. It is white and smooth-textured, according to the U.S. Department of Agriculture, and regular cream cheese has a milk fat content of no less than 33 percent. It needs to be refrigerated, but different things can happen to cream cheese if it's not.

The first American cream cheese was made by dairyman William Lawrence in 1872. According to Food Timeline, Lawrence overhead a Swiss man giving a cheese recipe. He ran home and promptly created cream cheese. Though originally made in New York, it adopted the name Philadelphia in 1880 because the city was considered to have the best food. The cheese was so popular other dairies began copying the product.

In 1928, Kraft merged with the Phenix Cheese Co., producer of Philadelphia Cream Cheese. The lifespan of the original product was a couple weeks, but after some patent changes in the mid-1940s, the cream cheese could last for four months in the refrigerator, according to Food Timeline. According to Shelflife Advice, refrigerated cream cheese stored below 40 degrees Fahrenheit should last one month past its expiration date.

According to the USDA, cream cheese is in the perishable foods category. If you are having a party and cream cheese is left out on a buffet, the USDA recommends a two-hour rule. After that time period, it should be discarded. Cream cheese normally has buttery taste. When it has spoiled, it develops a sour flavor. It can look watery, separated or dry.

Once cream cheese is no longer refrigerated, mold and bacteria will start to grow on it. According to the USDA, molds are microscopic fungi that reproduce through spores. Bacteria are one-celled creatures, while molds are multi-celled. Under the microscope, mold looks like mushrooms. To the naked eye, molds look fuzzy and come in different colors. Molds live everywhere and grow better in warm environments. Most molds are harmless and some common forms are Aspergillus and Botrytis. Mold growth is minimized by properly storing cream cheese in the refrigerator and using opened items within three to four days.