The official cause of death was acute toxicity from MDMA, the chemical name of Ecstasy, said Mike Sutcliffe, supervising coroner investigator for the San Bernardino County Sheriff's Department.
The death of John Hoang Dinh Vo, 22, of San Diego, was the second since 2013 attributed to Ecstasy of a person attending a rave at the San Manuel Amphitheater in Devore. Vo went into cardiac arrest after suffering a possible seizure at Insomniac's Beyond Wonderland rave held at the amphitheater, a venue owned by San Bernardino County. Insomniac is a subsidiary of Live Nation Entertainment.
Vo was in his senior year at UC Irvine and studying biology.
There have now been at least 23 confirmed drug-related deaths nationwide since 2006 among people who went to raves organized by Los Angeles-area companies. Eleven have died in Southern California — four in San Bernardino County and seven in Los Angeles County — and five in the Las Vegas area.
Vo was taken from the rave to Loma Linda University Medical Center and was pronounced dead after 11 p.m. March 20.
Insomniac began holding raves at the San Manuel Amphitheater in 2013, following complaints of drug use at the company's previous concerts at the nearby National Orange Show Events Center in San Bernardino. Insomniac has since resumed holding events at the National Orange Show center.
After Vo died last year, an Insomniac spokeswoman said that the company extended its "thoughts and prayers" to his family.
Beyond Wonderland returns to the San Manuel Amphitheater later this month for a two-day run on March 18 and 19.
Drug overdoses have been a major problem at electronic dance music festivals, where the use of Ecstasy and similar substances is closely tied to the rave experience.
Ecstasy can trigger dangerously sharp increases in body temperature, to as high as 109 degrees, which can cause organ failure and death. Ravegoers are often told to drink plenty of water, but some drink too much, which can cause their sodium levels to crash and trigger a seizure that makes it hard to breathe. Some people have slipped into fatal comas.
The drug can also cause the breakdown of muscle into a chemical that damages the kidneys, which can be fatal.
Doctors have said overdosing ravegoers have come into the emergency room with convulsions and heart attacks, leaving some who survived with brain damage as well as impaired speech and walking ability.