Sachin Mehta with the Belmont Center for Comprehensive Treatment says battling addiction is a lifelong and gruesome struggle for some people.
"It is extremely addictive physically as well as psychologically," he said.
Dr Mehta says addicts crave the highly euphoric feeling involved with drug use for as long as 6 months into sobriety.
"They continue to feel a little depressed; feel like something is missing in them, and this often leads to a relapse.
Garrett Reid had been struggling with drug abuse since 2001.
He was seemingly doing better last summer while working at Eagles training camp as a strength coach, until his life abruptly ended in an accidental heroin overdose while in his dorm room at camp.
Dr. Mehta says drug overdoses can occur after a period of sobriety.
"If they are able to stay clean for a period of about 6 months to a year, their bodies have gotten used to not being on drugs," said Dr. Mehta.
A weaker dose can push a user to increase drug increments; a bad batch can throw the body off.
"There might be heroin contamination with something else, and it's not as effective and it can produce a severe high and fatal outcome," he said.