A previously healthy 28-year-old man wound up in the emergency room with heart problems after drinking two energy drinks a day, as well as alcohol, for months, according to a new report.
The man experienced a very fast heart rate and an irregular heart rhythm (called arrhythmia), and the report supports a connection found in many previous studies: that there is a link between energy-drink consumption and heart problems.
Although the new report cannot prove that the energy drinks caused the man's abnormal heart rate, this case, combined with other previous reports, shows the abnormal heart rhythm "could be a complication" of energy-drink consumption, the researchers, from the University of Florida, reported in the July/August issue of the Journal of Addiction Medicine.
Given the popularity of energy drinks, doctors should consider asking patients about their energy-drink consumption if they have an unexplained heart rhythm problem, the researchers said. [5 Health Problems Linked to Energy Drinks]
Previous studies have found that consuming just one energy drink can increase blood pressure, sometimes to unhealthy levels. And there have been several reports of young people who have suffered heart attacks after consuming energy drinks, including a 2015 report of a 26-year-old who drank eight to 10 of these highly caffeinated beverages a day.
In the new report, the researchers wrote that the man went to the hospital after he started vomiting blood. He told the doctors that he had consumed two Monster energy drinks that day, each of which contained 160 milligrams of caffeine, for a total of 320 mg of caffeine that day. (For comparison, an 8-ounce cup of coffee contains about 95 to 200 mg of caffeine, according to the Mayo Clinic.) He also reported having consumed two to three beers that day.
A physical exam showed normal results, except that the man's heart rate was very fast — 130 beats per minute. (A normal heart rate is usually between 60 and 100 beats per minute.) A test of his heart's electrical activity showed he had atrial fibrillation, or an abnormal heart rhythm. The problem is not usually life-threatening, but it can increase the risk of stroke and other heart complications, according to the Mayo Clinic.
The man was treated with two heart medications (diltiazem and metoprolol), and his heart rate returned to normal within 24 hours. He was released from the hospital three days later, and as of one year after the incident, he had not experienced any more problems with his heart rhythm, the report said.
Monster energy drinks contain about four to five times the amount of caffeine per serving as caffeinated soft drinks. Caffeine can cause heart cells to release calcium, which may affect heartbeat, and high amounts of caffeine can cause heart palpitations and vomiting, the researchers said.
Between 2004 and 2012, the Food and Drug Administration received 40 reports of people experiencing health problems after drinking Monster energy drinks, including abnormal heart rate, increased blood pressure, loss of consciousness and cardiac arrest, the report said.
Still, up to 400 mg of caffeine per day is considered safe for healthy adults, according to the Mayo Clinic.
It's possible that other ingredients in energy drinks, along with caffeine, contribute to the development of heart problems, the researchers said. For example, taurine, a common ingredient in energy drinks, may heighten the effects of caffeine, the researchers said. Another ingredient, called guarana, also usually contains caffeine and may boost the caffeine content of the whole beverage above what's listed on the label, they said.
Further studies of the ingredients in energy drinks are needed for experts to better understand how the beverages may be linked with heart problems, the researchers noted.
Consuming alcohol along with energy drinks might also increase the effects of caffeine, allowing the compound to stay in the blood longer, the researchers said. Caffeine also could lower the sedative effects of alcohol, allowing people to continue drinking longer and consume more alcohol, which, in turn, could increase intoxication and lead to arrhythmias, they said.
Although the long-term effects of energy-drink consumption are not known, "it may be reasonable to limit their use, especially in combination with alcohol or illicit substances and in patients predisposed to arrhythmias," the researchers concluded.
At the time of publication, Monster Energy had not responded to an email request from Live Science for comment on the study.
Original article on Live Science.