After a healthy 16-year-old lost his life from a caffeine overdose, many are wondering how much caffeine is too much.

News 12 spoke with to Dr. Ernest Patti, an emergency medicine doctor at St. Barnabas Hospital to get answers.

Patti say too often he sees people go to the emergency room after taking too much caffeine at one time, especially in young adults.

He says caffeine overdose signs to look out for include jitters or restlessness, nausea, increased heart rate and a very serious symptom known as cardiac arrhythmia.

“Arrhythmia prevents your heart from pumping blood in its normal fashion," Patti says.

He says caffeine is OK in moderation, so people should stick to around 300 to 400 milligrams a day and to remember to stay hydrated.