WASHINGTON — Friends and family will be able to take the first step to save a loved one from an overdose of heroin or powerful painkillers called opioids.

The Food and Drug Administration (FDA) on Thursday approved an easy-to-use device that automatically injects the right dose of an overdose antidote named naloxone — commonly known by the brand name Narcan — before an ambulance arrives. Doctors could prescribe it for relatives or caregivers to keep on hand, in a pocket or a medicine cabinet.

Opioids include legal prescription painkillers, such as OxyContin and Vicodin, and illegal street drugs such as heroin.

The device, Evzio, contains naloxone, a long-used antidote for overdoses that is usually administered via syringe in ambulances or emergency rooms. But with the rise in drug-overdose deaths, there has been a growing push to equip more people with the protection.

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The FDA said Evzio’s design makes it easy for anyone to administer. Once Evzio is turned on, it provides oral instructions, much like defibrillators that laypeople frequently use to help those who collapse with cardiac arrest. It is about the size of a credit card or small cellphone.

The antidote is not a substitute for immediate medical care, the FDA said, as anyone who has overdosed will need additional treatment.

Still uncertain is how much the antidote will cost. Executives of the drug’s manufacturer, kaléo, of Richmond, Va., said it is too soon to say, but they are working with health insurers to get broad coverage.

FDA Commissioner Margaret Hamburg said 16,000 people die every year from opioid-related overdoses, and drug-overdose deaths are now the leading cause of injury death in the United States, surpassing motor-vehicle crashes. She said the increase in overdose deaths has largely been driven by prescription-drug overdoses.

“While the larger goal is to reduce the need for products like these by preventing opioid addiction and abuse, they are extremely important innovations that will help to save lives,” Hamburg said.

The use of Evzio is not without risks. Among the opioid-dependent, a shot of naloxone can cause sudden and severe opioid withdrawal, which can cause nausea, vomiting, accelerated heart rate, increased blood pressure, seizures and cardiac arrest.

Material from the Los Angeles Times is included in this report.