Singer Demi Lovato attends the 2015 MTV Video Music Awards at Microsoft Theater in Los Angeles, Aug. 30, 2015. Getty Images/ Jason Merritt

In many of the reports about singer Demi Lovato being rushed to the hospital for drug overdose, after allegedly being found unconscious at her Hollywood Hills home on Tuesday, the medicine Narcan was mentioned, administered to the artist by one of her friends, which could have potentially saved her life.

When TMZ updated their original article — in which they reported the 25-year-old “Skyscraper” artist was transported by the Los Angeles Fire Department for allegedly overdosing on heroin — they revealed further information about the incident, according to which, Lovato was given Narcan, before the paramedics arrived at her house.

Apparently, "one of her friends had Narcan on hand in case something like this happened," a source told Us Weekly. "Her friends knew this was coming because she’s been using so much again."

A source close to the singer told People Magazine later on that she was in a “stable” condition, and heroin was not the drug that she overdosed on.

Demi’s representative later released a statement that said: “Demi is awake and with her family who want to express thanks to everytone for the love, prayers and support. Some of the information being reported is incorrect and they respectfully ask for privacy and not speculation as her health and recovery is the most important thing right now."

So what is Narcan?

According to the drug’s own website, “nasal Spray is a prescription medicine used for the treatment of an opioid emergency such as an overdose or a possible opioid overdose with signs of breathing problems and severe sleepiness or not being able to respond.”

Also, the Substance Abuse and Mental Health Services Administration (SAMHSA), called it a nasal medicine that is effective in countering the effect of opioid overdose, which is approved by the Food and Drug Administration.

Narcan, also known as naloxone HCl, can also be injected straight into the veins. Once inside the body, it works by binding to opioid receptors to block or reverse the effects of opioids like heroin, morphine, and oxycodone, according to National Institute on Drug Abuse.

“It works instantly, almost like a smelling salt, returning the body to a pre-opiate state,” Cali Estes, founder of The Addictions Academy, told Yahoo Lifestyle. “However, its use is controversial because EMTs aren’t required to give it a certain number of times — some try twice, others three times, and that makes a difference in whether someone lives or dies.”

Estes added while it was mostly used to counter the ill effects of heroin in the past, “over the past three years, we’re seeing more cases of heroin laced with fentanyl.”

However, it is important to remember Narcan is not designed to take the place of emergency care and the patient is advised to get “emergency medical help right away after giving the first dose of NARCAN Nasal Spray, even if the person wakes up.”

Also, there are no guarantees with the drug as it fails to be effective, especially if the patient has too many drugs in his or her system or the medicine is administered too late.

Narcan is available for over-the-counter purchase in 46 states and can be bought with a prescription everywhere in the United States.