科學家報告一個咖啡因功能性飲料現在市場上應該有顯著的標識來標明咖啡因的含量以及對消費者健康的潛在影響
功能性飲料中咖啡因的含量差距可以達到十倍，其中一些功能性飲料含有相當于14聽可樂飲料的咖啡因。現在咖啡因的含量經常會沒有標識并且很少警告咖啡因所帶來的潛在的健康風險。文章的作者之一Roland Griffiths談到
沒有足夠的顯著的標識，消大多數費者可能將不明白他們將得到一點或是很多咖啡因。“它就像你在飲用酒精類飲品，但是你不知道它是啤酒還是威士忌” Griffiths談到。
一個普通的十二盎司可樂飲料含有大約35毫克咖啡因， 6盎司一杯的咖啡含有80-150毫克咖啡因。因為很多市場上的功能性飲料好像“定量的補充”，食品藥品管理局要求軟飲中的對咖啡因在界限（每罐12盎司聽裝飲料71毫克）沒有得到實行。咖啡因在功能性飲料中的含量從50毫克到500毫克不等作者寫道。
咖啡因中毒，是一個被確認的臨床綜合征，是被包括診斷和精神混亂統計指南和國際衛生組織認定的國際分類疾病，它的特點是神經過敏，焦慮，休息不良，失眠，腸胃失調，戰栗，心動過率，精神亢奮在少數情況下會導致死亡。
據美國毒品控制中心得到的報告，一些功能性飲料會顯示濫用咖啡因的不良反應。在2007年的一項調查中496例大學生接受了調查，51%的報告者稱在過去的一個月中他們至少消費了至少一種功能性飲料。在這些功能性飲料的飲用者中29%報告“搖擺和不穩定”，19%報告稱因飲用功能性飲料產生心悸癥狀。在相同的調查中顯示27%的受到調查的學生說在過去的一月中他們至少一次將功能性飲料和酒精類飲品混合飲用。“酒精增加危險的級別” Griffiths談到“因為高劑量咖啡因會給使用者判斷力造成錯覺這樣會導在致駕車時或其他方式讓他們自己處于危險中。”

Caffeine: Warning Labels for Energy Drinks
Scientists report that a slew of caffeinated energy drinks now on the market should carry prominent labels that note caffeine doses and warn of potential health risks for consumers.
“The caffeine content of energy drinks varies over a ten-fold range, with some containing the equivalent of 14 cans of Cola drinks, yet the caffeine amounts are often unlabelled and few include warnings about the potential health risks of caffeine intoxication,” says Roland Griffiths, one of the authors of the article.
Without adequate, prominent labelling, consumers most likely will not realise whether they are getting a little or a lot of caffeine. “It is like drinking a serving of an alcoholic beverage and not knowing if its beer or scotch,” says Griffiths.
A regular twelve-ounce cola drink has about 35 milligrams of caffeine, and a six-ounce cup of brewed coffee has 80 to 150 milligrams of caffeine. Because many energy drinks are marketed as “dietary supplements”, the limit that the Food and Drug Administration requires on the caffeine content of soft drinks (71 milligrams per twelve-ounce can) does not apply. The caffeine content of energy drinks varies from 50 to more than 500 milligrams, the authors write.
Caffeine intoxication, a recognised clinical syndrome included in the Diagnostic and Statistical Manual of Mental Disorders and the World Health Organization’s International Classification of Diseases, is marked by nervousness, anxiety, restlessness, insomnia, gastrointestinal upset, tremors, rapid heartbeats (tachycardia), psychomotor agitation (restlessness and pacing) and in rare cases, death.
Reports to U.S. poison control centers of caffeine abuse showed bad reactions to the energy drinks. In a 2007 survey of 496 college students, 51 percent reported consuming at least one energy drink during the last month. Of these energy drink users, 29 percent reported “weekly jolt and crash episodes ”, and 19 percent reported heart palpitations from drinking energy drinks.
This same survey revealed that 27 percent of the students surveyed said they mixed energy drinks and alcohol at least once in the past month. “Alcohol adds another level of danger,” says Griffiths, “because caffeine in high doses can give users a false sense of alertness that provides incentive to drive a car or in other ways put themselves in danger.”