What killed Bruce Lee? 4 leading theories medical and martial arts experts proposed after his shock death 50 years ago in July, 1973

Fluid build-up on the brain was given as the official cause when Bruce Lee died in 1973, but there was always doubt as to what exactly killed the martial artist
We look at some of the leading theories put forward at the time and more recently, from the actor’s use of cannabis to heatstroke to drinking too much water

American cinema

Mabel Lui

Published: 4:18pm, 19 Jul 2023

Why you can trust SCMP

Bruce Lee’s unexpected death on July 20, 1973 sent shock waves across the world.

Today, fans continue to mourn and pay emotional tributes to the martial arts legend, but people still don’t really know why he died.

At the time, doctors cited a fluid build-up in Lee’s brain as the official cause of death, but they did not give a clear explanation as to why the excess accumulation of fluid occurred.

Ahead of the 50th anniversary of Lee’s death, we recall some of the theories put forward to explain his death.

1. Cannabis use

When Lee died in 1973, he was just 32 years old. At the time, doctors at Queen Elizabeth Hospital in Hong Kong attributed his death to cerebral oedema – brain swelling. The condition, which is life-threatening, is the body’s way of reacting to trauma, a stroke or infection.

Bruce Lee in a still from “Fist of Fury” (1972).

Traces of cannabis were found in Lee’s stomach and small intestine when he died, according to a Post article dated September 19, 1973. As a result, some Hong Kong doctors believed that the brain swelling could have been brought on by ingesting marijuana.

Lee had previously been diagnosed with cerebral oedema on May 10 – just two months before his death – after he collapsed at a film studio and was in critical condition, according to Post articles from July 22 and September 21, 1973.

At the time, Lee had been dubbing the film Enter the Dragon. The actor had ingested some hash, fainted in the bathroom, and later vomited and fainted again before he was taken to hospital.

Bruce Lee ‘never before seen’ footage to be shown 50 years after his death

There, he was treated by neurosurgeon Peter Wu, who believed that cannabis use was a potential factor in Lee’s brain swelling.

However, this was, and remains, speculation – no causal link has ever been documented between cannabis use and and cerebral oedema.

2. Hypersensitivity to aspirin or meprobamate

Lee with Taiwanese actress Betty Ting Pei. The two spent time together soon before Lee’s death.

Shortly before Lee died, he was in actress Betty Ting Pei’s home on Beacon Hill Road, in Kowloon, Hong Kong, and complained of a bad headache.

He smoked some marijuana and Ting gave Lee an Equagesic pill, which contains meprobamate and aspirin, to relieve his pain. He then lay down to rest, but Ting was unable to revive Lee in the evening.

Leading pathologist Robert Donald Teare, who was a professor of forensic medicine at the University of London at the time, proposed that it was a hypersensitivity to the aspirin or meprobamate in the drug, or a combination of the two, that led to the cerebral oedema.

Bruce Lee in a still from “Enter the Dragon” (1973). Photo: TNS

This theory was corroborated by Ray Richard Lycette, a pathologist at Queen Elizabeth Hospital who performed the postmortem on Lee, according to Post articles from September 1973.

But, as with the cannabis theory, aspirin or meprobamate could not be definitively confirmed as the cause of death because neither are known to cause brain swelling. Ting also noted that Lee had taken Equagesic previously.

3. Heatstroke

In his biography Bruce Lee: A Life, author Matthew Polly posited another theory – heatstroke – for why Lee died.

In the two months before his death, Lee had lost 15 per cent of his body weight because of overwork, and weighed only 54kg (119lb).

The actor had also had his sweat glands removed from his armpits a few months earlier to avoid having sweaty armpits on screen, so his body’s ability to dissipate heat would have been lower than typical, Polly writes.

Is Fist of Fury Bruce Lee’s best film? The story behind its making

On May 10, when Lee collapsed while dubbing Enter the Dragon, the air conditioning in the dubbing room had been turned off to avoid sound issues with the recording. At the time, the actor exhibited high temperature, weakness, vomiting, loss of consciousness and more – all symptoms consistent with heatstroke.

Polly believes that Lee’s second collapse could have happened as a result of similar circumstances, and overheating could have been the cause of the headache that Lee mentioned having on the day of his death.

4. Drinking too much water

In December 2022, a study published in the Clinical Kidney Journal claimed that the real cause of Lee’s death could have been hyponatraemia, which occurs when there is a low concentration of sodium in the blood.

Is Fist of Fury Bruce Lee’s best film? The story behind its making

The study’s researchers, a group of doctors from the Autonomous University in Madrid, in Spain, claim that Lee may have drunk too much water, which could have led to low levels of sodium in his blood and meant that he was unable to excrete enough water to maintain water homeostasis (balance).

When he died, Lee’s lifestyle had put him at risk of hyponatraemia.

He had “chronic fluid intake” by virtue of his alcohol- and juice-based diet, smoked marijuana, and had also damaged his kidneys previously.

Lee circa 1970. He had “chronic fluid intake” by virtue of his alcohol- and juice-based diet. Photo: Getty Images

“We hypothesise that Bruce Lee died from a specific form of kidney dysfunction: the inability to excrete enough water to maintain water homeostasis,” the researchers wrote.

“This may lead to hyponatraemia, cerebral oedema and death within hours if excess water intake is not matched by water excretion in urine.

“Given that hyponatraemia is frequent, as is found in up to 40 per cent of hospitalised persons, and may cause death due to excessive water ingestion even in young healthy persons, there is a need for a wider dissemination of the concept that excessive water intake can kill.”