Caffeine is defined as a commonplace central nervous system stimulant drug which occurs in nature as part of the coffee, tea, yerba mate and other plants. It is also an additive in many consumer products, most notably beverages advertised as energy drinks and soda. However, as most of you may know, caffeine is most common (and abundant) in coffee. Caffeine is considered a psychiatric drug but works differently than most drugs; caffeine blocks adenosine receptors A and A2A. Adenosine is a by-product of cellular activity, and stimulation of adenosine receptors produces feelings of tiredness and the need to sleep. Caffeine’s ability to block these receptors means the levels of the body’s natural stimulants, dopamine and norepinephrine, continue at higher levels, which could result in paranoia, anxiety, and  insomnia. The worst of all is that it could lead to dependency on coffee, like with other drugs.

Mild physical dependence can result from excessive caffeine caffeine intake. Studies have shown that people who take in a minimum of one cup of coffee per day can acquire a physical dependence that would trigger withdrawal symptoms that include headaches, muscle pain and stiffness, lethargy, nausea, vomiting, depressed mood, and marked irritability, similar to that of most drug dependencies. According to Professor Roland Griffiths, neurologist at Johns Hopkins University, caffeine withdrawal should be classified as a psychological disorder. The research he conducted suggests that withdrawal symptoms began within 12–24 hours after stopping caffeine intake and could last as long as nine days.

So what does this mean? Caffeine isn’t dangerous. Abusing caffeine is dangerous. Just like pretty much anything else on the planet. It’s just easier to do with caffeine. A lethal amount of caffeine for the average person is 10 grams. The average 16 oz energy drink only has 180mg of caffeine. You would need to drink 50 energy drinks for a lethal amount. An energy drink a day won’t kill you, but it’s not healthy by any means. However, the most unhealthy part of an energy drink is the sugar, that 180mg of caffeine is fine, as it’s present in most other drinks such as soda and coffee. So take caution about simplifying the effects of caffeine use, addiction and withdrawal. Note, for instance, that there are enzymes that affect the rate of metabolism of caffeine, and the effectiveness of these enzymes can dramatically affect the duration of time that an individual is exposed to caffeine. People with less effective enzymes due to genetic differences as I have mentioned may have a stronger reaction to a single dose of caffeine than an individual who metabolizes the drug more quickly. This is not to mention that we could have genetic differences in the rates at which we increase adenosine receptors, or even the sensitivity of those receptors to adenosine, which could complicate factors even more.

It is easy for us to generalize about the effects and side effects of drug use, but more important that we understand the effects for each individual relative to their own genetic make up, their diet, their activity levels, the exposure to other substances that may influence metabolism of caffeine or its binding to serum proteins, etc.

I suppose if you are taking large doses of caffeine then the differences may not matter, because you’ll probably still have a bad headache if you don’t keep taking large doses, but for people taking less of a dose, these small variables become very important.