Preservatives are substances that are used in food, beverages, medications, cosmetics, and others. It mainly functions to prevent or inhibits the growth of microorganisms in the product. This ensures the product can be kept longer without contamination and oxidation. These preservatives can be either natural or synthetic. Types of preservatives include antimicrobials, antioxidants, and chelating agents. Examples of antimicrobials are sodium benzoate, methylparaben, and butanols. Whereas examples of antioxidants are butylated hydroxytoluene, ascorbic acid, and sodium edetate. These antimicrobial preservatives are mainly used in semi-solid or liquid forms of medications such as topical creams, eye drops, ear drops, injectables, solutions, and suspensions as they are at higher risk of contamination. Preservatives also have their own side effects depending on the type of preservatives used in the medications. Some people may also have allergic reactions to the preservatives used in certain medications. However, not all drugs and medications contain preservatives.