Coffee Health Risks

Caffeine is classified as a minor central nervous system stimulant. According to Harvard Health Publications, the effects of caffeine can be felt as fast as 15 minutes, and some of these effects can last up to six hours. In modest amounts, caffeine can have positive effects such as increasing alertness and concentration; Harvard Health Publication also states that it can protect against certain types of cancer. However, caffeine is addictive, and can cause serious health problems such as high blood pressure and cholesterol levels.

Overdose and Addiction

"The Diagnostic and Statistical Manual of Mental Disorders IV" explains that a caffeine overdose can cause such symptoms as anxiety. Some patients have even died after such an overdose, but it should be noted that a lethal caffeine level is the equivalent of approximately 80 cups of coffee. The American Heart Association states that drinking more than 4 cups of coffee per day can cause dependency and addiction, with withdrawal symptoms such as headache, anxiety, depression, drowsiness and irritability. These symptoms typically begin 12 to 24 hours after a person last had caffeine, and last approximately 2 to 3 days.

High Blood Pressure

According to MayoClinic.com, caffeine can cause a dramatic increase in blood pressure, even if the person does not normally suffer from this condition. Usually, this increase does not last long, and many people do not experience it at all. Although it is not quite clear what causes this increase in some patients, MayoClinic.com states that caffeine may block a hormone that widens the arteries. It has also been suggested that the increase may be due to the increase in the adrenaline release that caffeine causes. However, Harvard Health Publications states that moderate daily coffee consumption does not increase blood pressure in the long term.

Increased Cholesterol

Two substances found in coffee, cafestol and kahweol, have been shown to raise cholesterol levels in regular coffee drinkers, says Harvard Health Publications. Fortunately, paper filters have been shown to capture these substances. Interestingly, people drinking decaffeinated coffee are also at risk for an increase in cholesterol levels due to the type of bean that is used in such decaffeinated coffees.

Insomnia

MayoClinic.com states that after drinking coffee, it may take a person a longer time to fall asleep and reach deeper sleep stages. Since it takes a fairly long time for the caffeine to leave the body, any coffee drank less than 6 hours before going to sleep can cause insomnia.

Heart Attack and Arrhythmias

Some older studies claimed to have found a link between coffee and heart attacks as well as arrhythmias, or irregular heartbeats. Yet, according to Harvard Health Publications, there is very little evidence that coffee can cause either one of these conditions. An extensive longitudinal study among over 1,000 elderly people even found a lowered risk for different heart problems for the coffee drinkers. Some of the findings were reported by Dr. J.A. Greenberg and colleagues in the "American Journal of Cardiology" in December 2008.