What are the negative effects of caffeine?

Addiction

Caffeine is a drug, and people can become dependent on it. As with other drugs, long-term use of caffeine results in an increased tolerance, meaning that more caffeine is eventually needed to produce the desired effects. Taking caffeine away from an addict can produce withdrawal symptoms including headache, fatigue, irritability, poor concentration and muscle aches.

Dehydration

Caffeine is a diuretic, which means that it causes increased urination and can lead to dehydration. For that reason, it's a good idea to drink plenty of non-caffeinated fluids, especially in warm weather or when exercising.

Anxiety

Caffeine acts as a stimulant and, in high doses, can result in jitters, tremors and feelings of anxiety. At doses of about 600 milligrams or more (about six cups of coffee), people show signs of anxiety, including nervousness, sweating, upset stomach and tension.

Calcium Loss

Caffeine can cause depletion of calcium, an important mineral used to build bones. Over time, decreased bone density caused by lack of calcium can lead to osteoporosis, a disease in which bone loss occurs and bones are more easily broken or fractured.

Insomnia

In quantities greater than two grams per day, caffeine can cause insomnia by over stimulating the central nervous system. The effects of insomnia can be particularly pronounced in night shift workers who use caffeine to stay awake, but then find it difficulte to sleep during the day.

Miscarriage

Though the connection is still uncertain, several researchers believe that there is a link between miscarriage and excess consumption of caffeine. A 2006 study published in the American Journal of Obstetrics & Gynecology reported that pregnant women who consume more than 200 milligrams per day of caffeine double their risk of miscarriage. Caffeine consumed by a pregnant woman crosses the placenta to enter the bloodstream of the fetus. While this amount of caffeine may not have a great effect on the mother, the smaller size of the fetus magnifies the effect. Extremely limited intake of caffeine - two cups of coffee or fewer per day - during the first trimester is especially important.

Death

A caffeine overdose is not an easy feat, but it is possible. A lethal dose of caffeine is more than 10 grams, which is equivalent to drinking 80 to 100 cups of coffee consecutively.