Medication that have label indications mean that they were approved by the FDA. This means that they are clinically significant for the indication and manufacturers are allowed to market their drug for the indication. A drug can have more than one FDA labeled indication, this means they can be used for multiple medical conditions. As the evidence and consensus for use of the drug increases and strengthens, its class of indication is improved. Preferred drugs (and other treatments) are also referred to a "first line" or "primary" while others are called "second line", "third line" etc. A drug may be indicated as an "adjunct" or "adjuvant", added to a first line drug.