Whitney Houston
Whitney Houston would have celebrated her 50th birthday Friday. Reuters

Whitney Houston was submerged in a foot of bathwater for almost an hour before she was found dead at the age of 48 in February, according to the final coroner's report, released on Wednesday. Early reports suggested that a mix of cocaine, prescription medications and alcohol contributed to her death, and the newest report corroborates authority's suspicions.

Investigators found remnants of a fine white powder that tested positive for cocaine in the room with her, and toxicology reports showed that she also had marijuana, Xanax, Flexeril, a muscle relaxer, and Benyadryl, an allergy medication, in her system at the time of death.

We had approximately a 60 percent [obstruction] in the arteries, in the narrowing of the arteries, Craig Harvey, Los Angeles County Coroner's chief, told Good Morning America. So, that condition, complicated by the chronic cocaine use, all combined to result in her drowning.

The average woman has 12 percent artery obstruction.

Cocaine creates a euphoric feeling alongside increased energy and an elevated mood, but can have severe side effects.

In the short term, cocaine can interfere with the electrical system of the heart, according to WebMD. But years of cocaine use took its toll on her, Dr. Michael Fishbein, a physician at the University of California Los Angeles, told ABC News.

The long-term effect is that cocaine causes the heart to be enlarged, which increases the risk of sudden death, Fishbein said. It also causes scarring in the heart, which increases the risk of a sudden cardiac death, and it causes accelerated atherosclerosis, or a hardening of the arteries, which we associate with high blood pressure and smoking.

Cocaine can have a host of other effects as well. It is a vasoconstrictor, meaning it constricts the blood vessels throughout the body, which can lead to stroke, ulcers and sexual dysfunction, according to the National Institute on Drug Abuse. Long term cocaine use can also cause kidney failure and lung damage.

While water in her lungs proves Houston drowned, Fishbein said cocaine was likely the primary cause of death.

How does someone die in a bathtub? he said. It's not like they're swimming the English Channel. So she had to have been incapacitated. And I think that was due to the cocaine causing an abnormal cardiac rhythm.

Dr. Drew Pinsky, an addiction medicine specialist, told CNN that the combination of drugs could easily have caused Houston to drown.

To me, a sudden drop off in the Xanax level, a drop off in your alcohol consumption, add cocaine, that's a recipe for a seizure, he said. Somebody who's now upside down in a bathtub could easily seize and drown.

Houston's drug problem was no secret -- she admitted to using cocaine in 2002. However she vehemently denied ever using crack cocaine, a lower purity form of cocaine.

Crack is cheap. I make too much money to ever smoke crack, she said in a 2002 interview. Let's get that straight. OK? We don't do crack. We don't do that.

Houston battled addiction for years, she said in the interview.

The biggest devil is me, she said. I'm either my best friend or my worst enemy.

Her final project, a remake of the film Sparkle, is set to be released in August.