Eyeliner is a cosmetic product that is used to apply color to the area around the eyes to accentuate and highlight the appearance of the eyes. Eyeliners are used to emphasize the eyelids and/or to change the perceived shape of the eyes. They come in a variety of hues, from classic black to more adventurous options with glitter-flecked colors. Eyeliners contain special ingredients that apply color where it is needed in a precise and controlled manner. The products are specially formulated to ensure that potentially harmful microorganisms cannot grow and multiply. The safety of eyeliners is established by selection of ingredients that are safe and suitable for this purpose. In addition, eyeliners are assessed for their potential to cause skin irritation or cause allergic reactions. Product safety is also established through strict adherence to the principles of Quality Assurance and Good Manufacturing Practices.

Eyeliners contain the same basic kinds of ingredients, including film formers, thickeners, and pigments. Film formers deposit a thin layer on the skin, while thickeners help stabilize the formula so it will stick to the lids. Pigments include iron oxides to create blacks and browns, ultramarine for blue, chromium oxide for green, and titanium dioxide for white.

Some eyeliners contain lead, which is prohibited in cosmetics or personal care products in the U.S. The FDA has issued a warning for eye makeup products such as kohl, kajal, al-kahl, surma, tiro, tozali or kwalli, typically applied as eyeliner, as these products often contain lead.

There are also natural eyeliner formulas available that are free of harsh or harmful ingredients. These formulas may include fruits, minerals, and natural waxes like beeswax or carnauba wax. Some natural eyeliners are infused with plant-based ingredients like aloe and rosemary to soothe the delicate eye area.

In summary, eyeliners are cosmetic products that contain special ingredients to apply color to the area around the eyes. They are formulated to ensure that potentially harmful microorganisms cannot grow and multiply. Some eyeliners contain lead, which is prohibited in cosmetics or personal care products in the U.S. Natural eyeliner formulas are also available that are free of harsh or harmful ingredients and may include plant-based ingredients.