Speculation surrounding the cause of pop star Whitney Houston's death highlights what many forensic experts have known for years -- many prescription drug overdoses happen because people fail to realize how deadly combining medications can be.
An estimated 27,000 people died from accidental drug overdoses in the U.S. in 2007, one death every 19 minutes, according to the U.S. Centers for Disease Control and Prevention.
The U.S. death rate from drug overdosing has tripled in the past decade, making prescription drug abuse the nation's fastest growing drug problem.
Some of the commonly abused drugs include pain medications, anti-anxiety medications and stimulants. Most drug overdoses involve some combination of these medications, and some include alcohol.
Bottles of prescription drugs said to have been found in Houston's hotel room included Xanax, Valium and Ativan – all of which are prescribed to treat anxiety.
According to TMZ.com, officials said Houston had water in her lungs at the time of her death, but they haven't determined how much water was present previously, so they can't yet say whether the singer, whose body was found in a bathtub with her face reportedly underwater, drowned.
Dr. Cyril Wecht, a forensic pathologist and former coroner in Allegheny County, Pa., said if Houston did drown, she would likely have been heavily under the influence of numerous drugs to not wake up after she slipped underwater. He explained that the body has a physiologic need to breathe and will respond reflexively if the head is submerged underwater.
"If you are deeply unconscious to the point of a deep stupor, then it is conceivable that there was a heavy concentration of drugs," he said. Wecht said he had performed about 300 autopsies in the past year, and a significant percentage of the deaths stemmed from drug overdoses.
The average number of drugs involved in those cases, he said, was about five or six, which were mixed.
Addiction experts believe that Houston's struggles with substance abuse may have played a role in her death, and although Houston had entered rehab multiple times, she likely could not break the cycle of relapse and recovery that traps many addicts.
Relapse is very common, especially with alcohol and cocaine, which Houston admitted she'd abused.
"What often happens with illegal drug addiction is that the treatment involves legal drugs, which can be even more challenging to quit," said Alesandra Rain, a co-founder of Point of Return, an organization that helps people recover from prescription drug addiction. "Because Xanax is legal, it gives much the false sense that they are safe."
Previous studies that looked at the relapse rate among addicts found that between one-third and two-thirds of people who sought treatment for cocaine addiction used the drug again. A number of studies also found that most alcoholics who were in treatment programs drank again.
Studies also suggest that some people may be genetically predisposed to addiction. Experts can distinguish who may be at greater risk for addiction by looking at a patient's family history and monitoring the patient's reaction to the medication, said Dr. Daniel Angres, medical director of resurrection addiction services at Rush University College of Medicine. Many spiral into prescription drug abuse without realizing it.
"People may go to different doctors and receive different [medications], or even go to the same doctor and add on," said Angres. "These things have significant potential effects."
According to TMZ, Houston was seen leaving two different doctors' offices days before her death.