The popular stimulant, caffeine, is frequently making the headlines, and not always for the most encouraging reasons. Indeed, it was recently linked to two deaths due to its excessive volume in a since withdrawn lemonade offering from Panera Bread, a well-known bakery chain. Additionally, it has caught the attention of lawmakers given its presence in energy drinks predominantly marketed to children.

Still, this has failed to dampen its popularity in numerous products avidly consumed by the American public. Consider this - a staggering 70% of U.S. adults in a recent survey revealed they had sipped a cup of joe in the past 24 hours, the highest recorded figure in daily coffee consumption over the past twenty years. Moreover, the average American reportedly indulges in a sizable 10 pounds of chocolate annually.

Medical professionals, however, stress the importance of being aware of what exactly it is you're ingesting when you consume caffeinated items, and why excess can be detrimental. They explain that caffeine influences your central nervous system, generating a feeling of alertness and energy. As Rob M. van Dam, nutrition researcher and professor at The George Washington University states, "Caffeine reduces the effects of adenosine, a signal that makes you feel sleepy, by blocking the adenosine receptors."

It is also worth noting that caffeine can lead to increased urine output, trigger the release of acid in your stomach, disturb calcium absorption in your body, and raise your blood pressure. It reaches its peak in your blood an hour after consumption and its effects can last up to six hours.

Its impact isn't uniform across individuals. As Jamie Alan, an associate professor at Michigan State University, points out, persons with ADHD, for example, may feel sleepy after consuming caffeine and others might be more sensitive to its effects. Conversely, continued usage may result in reduced sensitivity and potentially, tolerance to the drug.

While doctors believe that all caffeine sources have a similar impact, they agree that some components in coffee may partially temper caffeine's effects - a topic warranting further research. It is, however, instrumental to monitor your total caffeine intake to prevent excessive consumption, van Dam adds.

Commonly consumed caffeine sources and their respective caffeine levels include coffee, tea, chocolate, soda, and energy drinks. More formidable offerings like special energy shots and certain types of candies often boast a particularly high caffeine content.

Take dark chocolate for instance, with 70% to 85% cocoa content, it contains over 22 milligrams of caffeine per ounce, as per the U.S. Department of Agriculture. Consuming more than an ounce can significantly up your caffeine intake unbeknownst to you.

So, how much caffeine is too much? The Food and Drug Administration (FDA) considers 400 milligrams of caffeine to be within the safe limit for the average adult. However, the rate of caffeine metabolism can greatly differ amongst individuals, according to van Dam. Pregnant women and persons with specific heart and cardiovascular conditions are advised to keep their caffeine intake considerably lower.

Exceeding your caffeine limit can cause discomfort and even severe symptoms such as seizures, hallucinations, and agitation. Rapid or irregular heart rates also warrant a visit to the ER. But in most cases, simply reducing future caffeine consumption should suffice, van Dam explains.

In case you're feeling okay after having too much caffeine, Alan suggests settling your stomach with an antacid or mild foods such as oatmeal or a banana. Light exercise can also help alleviate caffeine's effects. @@@ Protip: Moderate your future caffeine intake.