New London — An overdose victim in Stonington on Friday apparently was the ninth local person treated at Lawrence + Memorial Hospital since Wednesday night as a result of using a particularly potent batch of heroin being sold in the city.

In response to the spike in overdoses, the state Department of Public Health and the Connecticut Poison Control Center on Friday sent a statewide alert to hospitals, outpatient clinics and substance abuse treatment centers about the dangerous heroin in New London, according to William Gerrish, public health department spokesman.

The alert asks health care providers to warn their patients about the drug, he said.

In a news conference on Friday, L+M officials said the emergency department had treated seven patients who had overdosed on the lethal supply on Wednesday and Thursday.

An eighth person overdosed and died Thursday before being brought to the hospital.

Dr. Oliver Mayorga, chief of emergency medical services at L+M, said the emergency room also saw an additional six patients on Wednesday and Thursday who had overdosed from causes not related to the tainted heroin.

“What we’ve seen is a rash of overdoses, specifically heroin overdoses,” he said. “Most of the users were in their 20s and 30s. They were from all walks of life.”

The victims of the tainted supply were residents of New London, Waterford and other area towns. Mayorga said they were “veteran users” taking their regular amounts of the drug, but could not tolerate the particularly potent batch.

Ron Kersey, chief of emergency medical services at L+M, said EMTs administered Narcan, a medication that counteracts the effects of opiates, to all the patients where the overdoses occurred, then brought them to the hospital.

The patients all were experiencing breathing difficulties, among other symptoms.

“But the effect (of Narcan) doesn’t last as long as the opiate,” Kersey said. “After Narcan, you still need medical attention.”

Once Narcan takes effect and the patient resumes normal breathing, they often start vomiting and become agitated, among other effects, said Karen Butterworth-Erban, regional director of emergency services for the Eastern Region of Hartford HealthCare, which includes The William W. Backus Hospital in Norwich.

“One dose of Narcan is not necessarily enough to reverse the effects,” she said.

Mayorga said some patients needed one or more additional doses of Narcan at the hospital, in addition to other treatment. Some of the patients left the hospital “against medical advice” before they were stable.

“We’re not allowed to keep patients against their will,” he said.

Before the patients left the hospital, he said, emergency department staff provided them with information about local addiction treatment services and urged them to get help.

They also spoke with family members about getting help for their loved ones, he said.

“We would certainly welcome additional community resources,” he said.

Even before the spike in overdoses this week, L+M had been seeing an increase in the number of patients overdosing on heroin showing up at the emergency department.

L+M spokesman Mike O’Farrell said that in all of 2014, there were 74 heroin overdose patients. From January through November of 2015 — the most current data available — there were 93 heroin overdose patients at the emergency room, he said.

A similar increase at The William W. Backus Hospital in Norwich prompted the start of a pilot program to get more addicts into treatment, Butterworth-Erban said.

Backus treated 17 overdose patients in October and November, more than twice as many as the same two months in 2014.

This past fall, the hospital began a program with the state Department of Mental Health and Addiction Services in which emergency room nurses contact the department’s mobile outreach crisis workers whenever an overdose patient is brought to the hospital.

The workers normally interact mainly with mental health patients, Mason said, but are now expanding their outreach to addicts.

The crisis workers come to the hospital and give the patients information about treatment services, then follow up by phone or in person the next day, said Mary Kate Mason, spokeswoman for the department.

Thus far the crisis workers have seen 32 overdose patients. She said the program is thus far only being offered at Backus.

“We’ve been able to connect them with resources,” she said. “This is a new and very appropriate use of our mobile crisis teams.”

j.benson@theday.com

Twitter: @BensonJudy