How Dangerous Is Caffeine for People With Severe Arrhythmias?

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A recent lawsuit may serve as a reminder about how problematic caffeine can be for people with severe arrhythmias.

The parents of 21-year-old college student Sarah Katz are suing Panera Bread, alleging its “Charged Lemonade” played a role in her death. Katz had long QT syndrome type 1, so she avoided energy drinks, the complaint stated. The drink had up to 390 mg of caffeine in 30 fluid ounces, along with other stimulants and a lot of sugar — but lawyers argue Panera didn’t properly disclose its caffeine content and it wasn’t advertised as an energy drink.

Panera has since issued a warning that the drink should be used in moderation and isn’t recommended for “children, people sensitive to caffeine, [or] pregnant or nursing women.”

Guy Mintz, MD, of Northwell Health Sandra Atlas Bass Heart Hospital in Manhasset, New York, told MedPage Today that individuals with long QT are strongly advised to limit caffeine intake.

“The recommendations are either avoiding it or extreme caution in patients [and] young people with long QT syndrome who are drinking energy drinks,” Mintz said.

Studies of energy drink consumption among patients with long QT syndrome have showed a “significant increase in blood pressure, both the systolic and the diastolic numbers, and these correlated with the amount of caffeine that was in the blood,” Mintz said.

Mintz noted that caffeine can increase blood pressure, heart rate, and can cause palpitations. It can also lead to dehydration and has vasoconstricting properties that can actually lead to reduced blood flow, he said.

“Let’s say you have underlying heart disease and you drink a lot of caffeine, and then you’re going to go exercise, like a walk, you actually may decrease the blood flow within the heart,” Mintz said.

All of these factors can put more stress on an individual’s heart, which can be especially problematic for those with arrhythmias and other heart conditions.

Mintz suggested that individuals with long QT syndrome should moderate caffeine intake. Some medications — including antibiotics, antipsychotics, and antifungals — can also prolong the QT interval; adding caffeine to that mix can increase risks, he said.

The FDA considers 400 mg per day — about 4 to 5 cups of coffee — to be a safe amount of caffeine for the average person. Toxic effects such as seizures are possible with consumption of around 1,200 milligrams in a short period of time, the agency says. “People can consume 200 to 300 milligrams of caffeine a day and be perfectly fine,” Mintz added.

Still, people should be cautious about caffeine consumption, especially if they have an underlying heart condition.

“Energy drinks can raise blood pressure based on caffeine content, they can cause volume decrease, they can cause extra heartbeats, and people with underlying heart disease — and patients may not know they have underlying heart disease — should be cautious in consuming large quantities of caffeine,” Mintz said. “And patients should always maintain good hydration to counteract the diuretic effects of caffeinated beverages.”

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    Michael DePeau-Wilson is a reporter on MedPage Today’s enterprise & investigative team. He covers psychiatry, long covid, and infectious diseases, among other relevant U.S. clinical news. Follow

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