^Of course nothing is 100% safe, I thought what wiggi meant was that a particular person doing something risky and not dying doesn't mean it can't kill you. When you say I did it all the time and I was fine, people on here might assume that means that it's not dangerous, or that they will have the same results as you. People have definitely died from using cocaine while drinking alcohol.
There
is a consensus that cocaine + alcohol is much more likely to kill you than either cocaine or alcohol alone. As wiggi said, we can't know the precise likelihood of someone dying from their very first time combining cocaine and alcohol though, there is no data on that.
Cocaethylene has been found in high levels in the blood of victims of fatal drug overdose, in fact more fatalities involving cocaine have detectable levels of cocaethylene than do not. When cocaine and ethanol are taken together, effects are both stronger and longer, and heart rate is significantly increased, compared to administration of cocaine or ethanol alone
[source]. This subjects the heart and liver to a prolonged period of stress - some of the recorded deaths from cocaine+alcohol occur up to 12 hours after use.
The main causes of sudden death from cocaine use are central nervous syndrome seizures and hyperthermia, or cardiotoxicity.
Different sources have different statistics on the likelihood of sudden death from cocaethylene in comparison to cocaine alone, saying it is anywhere from 2 times as likely to cause death to 30 times as likely. Most say around 15-20 times.
A study on acute cocaine/ethanol administration in mice says:
In the combined cocaine-ethanol group, the total frequency of death was significantly increased (86%) as compared to the cocaine group (40%).
[Source]
This report says:
TThe most commonly recited effect of cocaethylene, as given in a 1990 New Scientist article, asserts that “When cocaine and alcohol are taken together, the combination is 21 times more likely to kill people with severe heart problems than cocaine on its own.” Whilst this statistic has been disputed, there is broad consensus that the effect of cocaethylene increases the risk of cardiac problems and other possible effects such as seizures and liver damage. It has also been linked to an increased risk of violent and impulsive behaviour.
*check that last report out for a whole bunch more good info on combining cocaine and alcohol.