The way coffee is portrayed in the media, you would think it's the lifeblood of the entire American working force, and to a certain degree, it is. While a large number of working Americans can barely function in the morning without that first cup of Joe, prolonged use of coffee can have more negative benefits than positives -- damaging your teeth, breath and even your skin.
Tannin is a chemical that is found in both coffee and tea. Commercially, tannin is used in tanneries when processing leather to make the leather soft and shiny, which is a good indicator that you shouldn't be drinking it. Tannin blocks the pores of cells, preventing them from receiving nutrients provided by food. Other adverse aspects of tannin that make it great for leather treatment are its hydration-removal properties, which can cause your skin to become rough and brittle over time.
A common skin problem found primarily in older people is liver spots. These dark splotches are caused by a high level of toxicity and congestion in the liver. Your liver acts like a filter for your body, purifying your blood so your cells can receive oxygen and nutrients. Long-term coffee use may block your liver with toxins, preventing your liver from purifying your blood, according to Chet Day's Health and Beyond Online. This impure blood then taints the cells in your body, including skin cells, which may result in the development of liver spots as you age.
In addition to the dehydrating effects that tannin has on your skin, the caffeine in coffee, when taken in high amounts, also acts as a diuretic, which further dehydrates your body. Diuretics cause you to urinate more frequently, which can dry out your body as well as your skin. While drinking only a few cups of coffee won't dehydrate you too badly, when you get up to 4 to 7 cups a day, it may become problematic.
The connection between caffeine and acne has been a topic of hot debate over the years, with inconclusive results on both sides of the argument. However, some experts believe that while caffeine may not be a cause of acne, it could worsen the already existing condition, says AbsoluteAcneInfo.com. The toxic effects that coffee can have on your liver can also lead to acne, as the liver is unable to purify your blood, resulting in tainted skin cells.