The deaths of three people are under investigation in connection with the NHS 111 non-emergency phone line, according to a report.
The general practitioners trade magazine Pulse reported that at least 22 possible "serious untoward incidents" (or SUIs) related to NHS 111 have been reported since the launch of the service.
Those incidents included three where a patient died, the magazine has claimed.
Two of the deaths occurred in the East Midlands, and one in the West Midlands.
The deaths reportedly include the case of a 47-year-old who died from a suspected overdose.
That death occurred after relatives contacted NHS 111 requesting mental health assistance, Pulse reported.
A further 19 possible SUIs have been recorded by providers or commissioners, the magazine added.
Rolled out across most of the country last month, the NHS 111 service is for people urgently seeking medical help or advice but who are not in a life-threatening situation.
The service was introduced to replace NHS Direct in England and is meant to ease pressure on emergency 999 call centres.
NHS England said it could not verify the data reported in Pulse, however it issued a statement in response to the magazine's report.
"The safety of patients must be our paramount concern and NHS England will keep a careful eye on the situation to ensure NHS 111 provides not only a good service to the public, but one which is also safe," the statement read.
Earlier this week, NHS England announced a review of the 111 service.
A spokesman said: "The performance standards which have been introduced for NHS 111 represent a gold standard which the majority of NHS 111 services in England are now meeting, though in some areas performance is still unacceptable, especially at weekends.
"Some local providers of NHS 111 have not provided the prompt, reliable service the public need and want.
"NHS England's board is determined to ensure that the public have access to a gold standard NHS 111 service wherever they live in England."
But Clare Gerada, chairwoman of the Royal College of General Practitioners, raised concerns about the free-to-call advice line.
"It is extremely worrying that there is still so much uncertainty around the delivery and reliability of the advice provided by NHS 111 in some areas.
"We are also concerned that patients are losing confidence in the new service before it is even fully up and running.
"We call on NHS England to provide more reassurance about its effectiveness and ability to deliver the necessary standards of care for all patients using the service, right across England."
Mrs Pooja Virk from Hornchurch, Essex, contacted Sky News after her nephew was taken ill recently. His ears ached, he had a high temperature and was feeling breathless.
She said: "I called my doctors and got the answer message to call 111.
"I explained his symptoms and the lady on the other end said 'oh take him to the chemist, not life threatening symptoms'."
When she got to the pharmacy she says the pharmacist laughed at the advice she had been given and said he needed to get urgent medical help.
Mrs Virk took him to a local hospital. She said: "They checked him straight away and said you are so lucky you brought him in on time he is suffering from an asthma attack.
"If you had left it any longer you would have been rushing in an ambulance with him!"
She added: "Soon there is going to be a very bad public clash with the NHS if it's not sorted."
Philip Hammond inspected the F-35 after meeting US counterpart Chuck Hagel
The F-35B after its first landing on an Atlantic Ocean aircraft carrier
Local county council election results
David Davis (L) lost the contest to become Tory leader to David Cameron (R)
UKIP leader Nigel Farage said the elections marked a 'game-changer'
Staff at the solicitors reported a bad smell before the body was found
April Jones in a leisure centre a couple of hours before she vanished
April, five, went missing on October 1 last year
Mark Bridger denies abducting and murdering April Jones
Sappers Patrick Azimkar (L) and Mark Quinsey were killed in the attack
13% of borrowers were unaware they needed an interest-only repayment plan
Mortgage lenders will contact homeowners considered most at risk
Mastiffs are heavily armoured in order to provide protection from bombs
The men were on a routine patrol in Helmand Province
April was last seen riding her bike close to her home in Machynlleth 
An officer walks down the driveway of Mr Roache's home following his arrest
Bill Roache, with Anne Reid, who played his first wife in the TV soap
The hotel is said to be used by a number of celebrities
Police arrive to investigate the deaths of the hotel guests
April Jones' family arrive at Mold Crown Court
Wrexham's former Bryn Estyn home, one where abuse is known to have happened
Clarke Carlisle said some were "disgusted" by the routine
Floral tributes have been left by friends and family
Forensic experts on the M9
Mr Cable says the issue is unlikely to be addressed by this Parliament
Dubai has become a major destination for tourism