Hypoallergenic eyeliner is a cosmetic product marketed to cause fewer allergic reactions. Typically, companies that offer hypoallergenic eyeliner emphasize that it is gentler, safer and ideal for use by contact-lens wearers, people with allergies and those with sensitive eyes.
As of 2014, there are no federal regulations that mandate the use of the term "hypoallergenic." It is completely up to the manufacturer of a product whether or not to label the product as such.
Labeling cosmetics as "hypoallergenic" first became popular in the 1970s. In 1975, the Food and Drug Administration attempted to regulate use of the term by issuing a rule stating that a product could only be labeled "hypoallergenic" if there were scientific studies conducted that proved it caused fewer adverse reactions than non-hypoallergenic products. That rule was later declared invalid by U.S. courts, allowing manufacturers to use the term freely and without obligation.
The term "hypoallergenic" is used primarily for marketing purposes as there is no way to eliminate the possibility of allergic reactions to products completely. All ingredients are required to be listed on cosmetic product labels, so people with allergic tendencies to known ingredients must read labels carefully before using products. It is best to test products on the inner forearm for several days to see if an allergic reaction occurs.