What it is: Caffeine in its pure form is a bitter, white substance that acts as a stimulant drug. Its other properties make it an increasingly popular ingredient in beauty products.

Where it comes from: Found in the beans, leaves, and fruit of some plants, caffeine acts as a natural pesticide, killing insects that feed off these plants. Most of the caffeine we consume comes from the coffee bean, which is the seed of the coffee plant.

Properties: Pure caffeine is an odorless white crystal or powder that is intensely bitter. In humans, it stimulates the central nervous system, temporarily warding off drowsiness and restoring alertness.

What it’s good for: Caffeine is the main ingredient in anti-cellulite creams, temporarily dehydrating fat cells and making them smaller and the skin look smoother. As a vasoconstrictor, it’s used in de-puffing eye creams to temporarily tighten skin and reduce dark circles. By constricting blood vessels, it helps temporarily deflate puffy eyes, reduce the appearance of dark circles, and minimize facial flushing. The acid in it functions as an antioxidant, and studies have found that caffeine may protect against sun damage to skin cells, and even repair damaged cells. Ground coffee beans are also an excellent exfoliant in scrubs.

Where you’ll find it: It can be found in eye creams and anti-cellulite creams, sunscreens, and beauty products such as body washes, soaps, lip balms, and scrubs. It’s also found in popular drinks, including coffee, tea, the mate drink popular in South America, colas, and other soft drinks.

Other uses: Often added to over-the-counter medications like pain relievers and cold remedies, caffeine additives make pain relievers 40% more effective. It’s a common ingredient in headache medicine as it helps the body absorb the drug quicker so it brings faster relief.

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