Oct. 24, 2012 -- A wrongful death lawsuit against Monster Beverage Corp., and the release of Food and Drug Administration incident reports indicating that Monster Energy drinks might have been responsible for five deaths since 2009, have brought questions about death by caffeine back into the national spotlight.
Although death by caffeine is possible, it generally takes 5 to 10 grams of the stimulant to kill someone, toxicologists say. Anais Fournier, the 14-year-old Maryland girl at the heart of the lawsuit, whose parents allege the energy drinks caused her death, consumed 480 mg of caffeine over two days, or less than a gram of the stimulant.
"This dose would not be expected to be fatal in a normal person of that age," said Dr. Christopher Holstege, director of toxicology at the University of Virginia School of Medicine.
Then again, what's lethal depends on several factors, including a person's weight, medications and underlying health conditions. A 41-year-old woman lived after consuming 50 grams of caffeine, up to 10 times more than what's considered a lethal dose, according to a 2003 Journal of Toxicology article.
"It is very difficult to predict one's response to caffeine. Some people are more sensitive than others," said Bruce Goldberger, the director of toxicology at the University of Florida College of Medicine. "Therein lies the problem. If someone has an undiagnosed medical condition, they may ingest caffeine not knowing it may have a deleterious effect, such as a cardiac arrhythmia, hypertension or anxiety."
Fournier drank two 24-ounce cans of Monster Energy during two consecutive day trips to the mall last December, before going into cardiac arrest at her home on Dec. 17, according to the criminal complaint filed in California Superior Court last week. She never regained consciousness and was taken off life support two days before Christmas.
Medical examiners determined that Fournier died of "cardiac arrhythmia due to caffeine toxicity complicating mitral valve regurgitation in the setting of Ehlers-Danlos syndrome."
In other words, the caffeine caused her irregular heartbeat, but Fournier had a heart valve that was already leaking because of an underlying genetic disorder before she consumed the energy drinks.
"It would be difficult to specifically attribute caffeine as the primary cause of an aneurysm rupture and subsequent death in such a patient, even following high doses," Holstege said, adding that Ehlers-Danlos syndrome has several complications, including aortic and cerebral aneurysms.
Doctors never analyzed the caffeine in Fournier's blood, according to the autopsy report. The 480 mg figure stated in court documents comes from the knowledge that Fournier drank two 24-ounce cans, containing 240 mg of caffeine each.
It's possible that her caffeine consumption was underreported, which is a problem in the field of toxicology with teenagers and adults, said Marcel Casavant, the chief of toxicology at Nationwide Children's Hospital in Ohio.
Fournier's parents claim in their lawsuit, among other allegations against Monster Beverage Corp., that the energy drink giant failed to warn consumers about the dangers of the high caffeine content in its beverages, and that the company uses names like "Assault" and "Dub Edition" to market its drinks to young people.
Labels on Monster cans do not say how much caffeine is inside, but they warn that the product is not recommended for children or people who are sensitive to caffeine. Depending on the size of the can, labels suggest limiting the number of cans consumed per day to two or three.
In its response to the lawsuit, Monster Beverage Corp. said in a statement that it was "saddened by the untimely passing of Anais Fournier. ... Over the past 16 years, Monster has sold more than 8 billion energy drinks, which have been safely consumed worldwide. Monster does not believe that its beverages are in any way responsible for the death of Ms. Fournier. Monster is unaware of any fatality anywhere that has been caused by its drinks."
Since energy drinks are classified as dietary supplements, they are not limited to the FDA's 200 parts per million caffeine limit on sodas. (Coca Cola Classic has 30 to 35 mg of caffeine per 12-ounce can, but 12 ounces of the Monster drink Fournier consumed would have four times that.) The FDA, however, still keeps track of deaths and hospitalizations attributed to products, FDA spokeswoman Shelly Burgess told ABCNews.com.
Since 2004, 18 hospitalizations and five deaths have been reported in connection with Monster Energy drinks, according to reports obtained by ABCNews.com from the American Association for Justice. It is not clear from the reports whether the victims had underlying health conditions.
AAJ got the "adverse event" reports from Wendy Crossland, Fournier's mother, who submitted a Freedom of Information Act request to the FDA for Monster-related health problems after her daughter's death. Other energy drink brands are not included in the reports.
The FDA has not launched a formal investigation of Monster Beverage Corp., Burgess said.
Monster Beverage Corp. stock fell by 10 percent this afternoon, after it fell by more than 14 percent on Monday, following news stories about the deaths.