Overworked family doctors have admitted they sometimes misdiagnose patients because appointment times are far too short.
Some 35% of GPs said that they have missed symptoms while assessing cases and 80% said they do not always have time to diagnose properly.
And 55% fear they have missed serious health issues while 37% believe they have prescribed the wrong course of treatment.
Around half of the 200 family doctors polled by law firm Slater and Gordon said they are expected to keep appointments under 10 minutes.
Others said they were pressured to reduce this even further.
Dr Eleanor Holmes, 39 qualified as a GP in 2008. She worked for 10 years in Newcastle and Northumberland.
She said: “I’m now on a sabbatical because working as a GP within the NHS had become so bad for my health.
“No matter what changes I made I couldn’t make it healthy or safe to continue working.
“A ‘typical’ workload is 30 patients each day, over 10 to 12 hours. Normally this would look like 14 patients in the morning, followed by two home visits, then 14 patients in the afternoon. Appointments are generally 10 minutes long but can vary between practices.
“If you’re ‘on-call’ and triaging patients on the phone you could speak to double that in a morning. When I was ‘on call’ I could have contact with 50 or 60 patients, or more, a day. This is not safe working.”
On average, patients get nine minutes and 12 seconds with their GP. In the poll, 94% of NHS doctors said short appointments put patients at risk and a minimum “safe” time is 16 to 20 minutes.
One GP said: “Recently it took three weeks and repeat appointments to get to the bottom of a patient’s medical condition and offer the correct solution. It made me feel terrible."
Prof Helen Stokes-Lampard, chair of the Royal College of GPs, said: “We have called for 15-minute appointments as a standard, with longer for those patients with complex health needs who need it.”
NHS England said: “Doctors decide on the length of appointments. If a patient needs longer, they should be given it.”
