"You may need to take medicines every day or only once in a while, and you want to make sure that they are safe and will help you get better. In the United States, the Food and Drug Administration is responsible for assuring the safety and effectiveness of prescription and over-the-counter medicines. Even safe drugs can cause unwanted side effects or interactions with food or other medicines, and they may not be safe during pregnancy. Taking medicines correctly can reduce the risk of reactions and help ensure that you get better. Generic drugs are important options that allow greater access to health care. They are copies of brand-name drugs and are the same in dosage form, safety, strength, route of administration, quality, performance characteristics, and intended use. FDA-approved generic drugs must meet the same rigid standards as innovator drugs and have the same high quality, strength, purity, and stability. Generic manufacturing, packaging, and testing sites must also meet the same quality standards as brand-name drug sites. A generic drug is identical or bioequivalent to a brand-name drug in dosage form, safety, strength, route of administration, quality, performance characteristics, and intended use. Although generic drugs are chemically identical to their branded counterparts, they are typically sold at substantial discounts. Generic drugs are usually less expensive because their manufacturers do not develop the drug from scratch, although they must show that the product performs in the same way as the brand-name drug. Generic drugs are as effective as brand-name drugs in dosage, safety, strength, quality, how they work, how they are taken, and how they should be used. Not every brand-name drug has a generic version. New drugs are initially protected by patents, most of which last 20 years. When a patent expires, other companies can sell a generic version after testing and FDA approval."