In a move aimed at stemming the tide of deaths caused by the nation’s prescription drug epidemic, the Food and Drug Administration on Thursday approved a new device that would allow family members or caregivers to administer emergency medication to combat an overdose.

The product, Evzio, rapidly delivers a dose of naloxone, a long-used antidote to overdoses of a powerful class of painkillers known as opioids, which include legal drugs such as Vicodin and OxyContin, as well as illicit drugs such as heroin. The treatment would be administered through a hand-held automatic injector that, when activated, gives spoken instructions to the user and is small enough to carry in a pocket.

Federal officials fast-tracked the approval of Evzio — the FDA reviewed its application in less than four months — saying it could play a critically important role in preventing some of the estimated 16,000 annual deaths attributed to prescription drug overdoses, a problem that has grown steadily worse over the past decade.

Opioid overdoses are marked by slowed breathing, extreme fatigue and changes in heart rate. Because victims tend to lose consciousness and fall ill quickly, allowing nearby family members or caretakers to administer naloxone rather than waiting on paramedics or doctors could mean the difference between life and death.

“For years, the lack of a lay-friendly delivery system has made it difficult to make naloxone broadly available to the public and to foster its use in non-medical settings, where it is often most urgently needed,” FDA Commissioner Margaret A. Hamburg told reporters Thursday, calling Evzio “an extremely important innovation that will save lives.”

Regulators warned that Evzio should not be considered a substitute for medical care, that it works only temporarily to reverse overdose effects, and that it can trigger opioid withdrawal symptoms, including nausea, vomiting, sweating, uncontrollable trembling, and increased heart rate and blood pressure.

Still, the approval of Evzio will for the first time allow people with no medical knowledge to inject the drug into a patient’s muscle or under the skin during an emergency by walking them through each step verbally, much like an automated defibrillator.

Family members or caregivers will need to get a prescription for the product ahead of time. But doing so would allow them to have a portable dose of naloxone in an easy-to-use injector about the size of a credit card and the thickness of a cellphone.

“This is an important milestone for the millions of patients taking opioids who are trying to balance pain management with the safe use of opioids, as well as those who are struggling with abuse,” Eric Edwards, chief medical officer of Kaleo, the maker of Evzio, told reporters Thursday. “What we’ve realized is that opioid overdoses do not discriminate. . . . We want to make sure this product is made available to all who could benefit from it.”

Company officials said they have yet to set a price for the device, in part because the FDA approval came so rapidly. But chief executive Spencer Williamson said the company will try to make sure opioid users have access to it, “regardless of their ability to pay.”

The FDA used Thursday’s approval as an opportunity to underscore other actions the government has taken in recent years to combat opioid misuse and abuse that has crippled communities throughout the country. Those efforts include altering the labeling of certain opioid drugs, requiring manufacturers to conduct long-term studies about the safety of their drugs and encouraging development of tamper-resistant forms of existing opioids and new pain treatments that are not so addictive.

At the same time, the FDA continues to face faces criticism for not doing more, and for potentially allowing the overdose epidemic to grow worse. The agency encountered a wave of opposition to its approval last fall of a new opioid, Zohydro, the first prescription narcotic comprising a pure dose of hydrocodone. Officials in Massachusetts last month blocked sales of the drug, with Gov. Deval L. Patrick (D) citing a public health emergency.

Although the FDA agreed with the drug’s manufacturer that the pure hydrocodone formulation allows chronic pain sufferers to use the drug over the long term without the risk of liver damage, critics have warned that such a formulation makes the drug easier to abuse. Last month, the manufacturer of another opioid drug, Oxy­Contin, said it plans to seek FDA approval for a tamper-resistant form of hydrocodone that would be less prone to abuse.

Various states, their economies battered and their workers hampered by addiction, have taken aggressive measures in fighting prescription drug abuse. They include tighter drug monitoring programs, stricter “doctor shopping” laws, increased treatment and counseling and intensified law enforcement efforts to crack down the illicit sale of prescription drugs. Some police agencies have equipped officers with naloxone in an effort to get treatment to users suffering an opioid overdose before paramedics arrive.

Some medical providers have expressed worry that Evzio could create a false sense of security among heavy opioid users, but the reaction to Thursday’s approval by the FDA was overwhelmingly positive among health-care providers and addiction groups.

Knox Todd, a Texas emergency room physician who spoke on a call organized by Evzio’s manufacturer, said the approval will create an even better opportunity to prevent many overdoses from becoming deadly. “This will expand the availability of what we know is a life-saving drug,” he said, “to a larger population who can use it.”