It has become an all-too-familiar story in schools across the country: A child eats a peanut or is stung by a bee and suffers an immediate, life-threatening allergic reaction known as anaphylaxis.

If parents and school authorities know about the allergy and a doctor’s prescription is on file, a nurse can quickly give an injection of epinephrine, saving the child’s life.

But school nurses in many districts face an agonizing choice if a child without a prescription develops a sudden reaction to an undiagnosed allergy. Should they inject epinephrine and risk losing their nursing license for dispensing it without a prescription, or call 911 and pray the paramedics arrive in time?

After a 7-year-old girl died in January in a similar case in Virginia, the state passed a law that allows any child who needs an emergency shot to get one. Beginning this month, every school district in Virginia is required to keep epinephrine injectors on hand for use in an emergency. Illinois, Georgia and Maryland have passed similar laws, and school nurses are pushing for one in Ohio. A lobbying effort backed by Mylan, which markets the most commonly used injector, the EpiPen, made by Pfizer, led to the introduction last year of a federal bill that would encourage states to pass such laws.

Mylan has also lobbied state legislatures around the country directly and is passing out free EpiPens this fall to any qualifying school that wants them.

"When a child is having an anaphylactic reaction, the only thing that can save her life is epinephrine," said Maria L. Acebal, chief executive of the Food Allergy and Anaphylaxis Network. "911 doesn’t get there fast enough."

The efforts are an acknowledgment of the rising rates of food allergies among children and a handful of deaths from allergies across the country. In many schools, children carry their own epinephrine injectors in their backpacks to use themselves, if they’re old enough, or the devices are stored on their behalf in nurses’ offices.

The initiative also has a commercial underpinning: It is part of an effort to raise the profile of EpiPen. Over the last two years, Mylan has invested millions of dollars in consumer advertising and hired almost 100 extra sales representatives to help promote the product. EpiPen sales are on track to bring in $640 million this year, a 76 percent increase over last year, according to one analyst.

Heather Bresch, the chief executive of Mylan, said charity and profit should not be mutually exclusive.

"I think this goes to the heart of being able to do good and do well," she said.

Although no one knows exactly why, the rate of food allergies among children appears to be on the rise. One recent survey found that in 2008, one in 70 children was allergic to peanuts, compared with one in 250 in 1997.

"I don’t think it’s overdiagnosis," said Dr. Scott H. Sicherer, the author of the report and a researcher at the Jaffe Food Allergy Institute at Mount Sinai Medical Center in Manhattan. "There really seems to be a difference."

A study last year in the journal Pediatrics found that about one in 13 children had a food allergy, and nearly 40 percent of those with allergies had severe reactions. A recent survey in Massachusetts, where schools are permitted to administer epinephrine to any student, found that one-quarter of students who had to be given the drug for a reaction did not know they had an allergy. But in many schools, employees are not allowed to use epinephrine injectors on children who do not have a prescription.

That’s what happened in January when Amarria Johnson, a first-grader from Chesterfield, Va., developed a severe allergic reaction. Her mother, Laura Pendleton, said Amarria’s allergy to peanuts was known, but the school did not have an EpiPen that was prescribed to her. At the time, school employees were not allowed to use injectors that were prescribed to other children.

Another student gave Amarria a peanut during recess, and by the time paramedics arrived, Amarria had stopped breathing and could not be resuscitated, according to the Chesterfield County police. In April, Virginia’s governor signed a law that lifted those restrictions and required all schools to carry injectors for emergency use.

Pendleton said parents could not police everything their child ate.

"You need to have the EpiPens there just in case," she said.

Epinephrine is known as a relatively safe drug, with few adverse effects if the drug is given when it is not needed.

"Our motto has always been in training our staff, if you think epinephrine, you give epinephrine," said Nancy Markley, who oversees the school nurses and health clinics in the Loudoun County schools in Virginia.

Bresch said schools were just the first step in a plan to make emergency epinephrine injectors more widely available in restaurants, airplanes and other public places, much as external defibrillators are today. Mylan has hired consultants who once worked for the device maker Medtronic when it was trying to make defibrillators more widely available.

"It’s a complex undertaking and complicated," Bresch said. "But I think it’s doable."

Acebal’s group has not taken a position on placing injectors in public places other than schools. Sicherer said the issue became less clear in settings like restaurants, where a waiter might not be able to differentiate between choking, a heart attack or anaphylaxis.

"I think that gets to be a little more controversial about upsides and downsides," he said.

EpiPen commands more than 95 percent of the market for epinephrine injectors and is so dominant that its name has become synonymous with the category itself. But until recently, Mylan did not do much to sell the product. The company acquired the brand in 2007 as part of deal with the German company Merck.

"It became very apparent that there was a lot more we could be doing with EpiPen," Bresch said, adding that just 7 percent of people at risk for severe reactions carry a prescription for one.

Mylan began working with allergy advocates and lobbying state and federal politicians to enact laws permitting the broader use of EpiPens. Politics are nothing new to Bresch: She is the daughter of Sen. Joe Manchin, D-W.Va. The company also invested in consumer advertising, spending close to $15 million in the last two years on television commercials and other advertising, according to Nielsen.

Gary Nachman, an analyst for Susquehanna Financial Group, said EpiPen was "extremely important" to Mylan. He estimated that EpiPen would account for $640 million of Mylan’s $840 million sales this year in brand-name products, and that sales would continue to grow in the double digits for the next few years.

"This is basically the workhorse for them in their branded business," Nachman said.

Doug Tsao, a pharmaceuticals analyst for Barclays, said Mylan’s efforts in schools had an added benefit.

"When the school nurse uses EpiPen, what does the nurse refer parents to?" he said. "I think that is absolutely part of the motivation."

Two coming events may be giving Mylan pause: In November, Sanofi plans to introduce a rival device, and in 2015, Teva may win approval of a cheaper, generic version of the EpiPen.

Sanofi’s product, the Auvi-Q, has a rectangular shape and the added feature of voice instructions to help a user use the device. Teva’s product, if approved by the FDA, would closely mimic the EpiPen design and, like a generic drug, could be substituted by pharmacists even if doctors prescribed the EpiPen.

Sicherer said the Auvi-Q had potential advantages over the EpiPen, which is shaped like a felt-tip marker and can be awkward to carry. Sanofi has boasted that the Auvi-Q is shaped like a cellphone and can slip into a pocket.

In addition, "it’s voice-guided," Sicherer said. "This is a whole new world."

Bresch said that because so few people at risk for allergic reactions use EpiPens, there was room in the market for a competitor.

"There’s still a lot of people that we need to get to," she said.

Ken Cacciatore, an analyst at Cowen & Co., questioned whether parents would be willing to switch to a different brand in such life-or-death situations.

"Parents may want the real thing," he said.