Systems have gone down at Morecambe GP surgeries as part of a worldwide IT outage also affecting airlines, railways, media and banks.
Cybersecurity firm Crowdstrike says a "defect" in one of its software updates hit Windows operating systems on Friday.
"This is not a security incident or cyberattack...the issue has been identified, isolated and a fix has been deployed," said a spokesperson for the firm.
A post on the Bay Medical Group Facebook page on Friday said: "BMG patients, like the rest of the world we are experiencing technical issues with our computer systems today 19th July 2024.
"This is causing major disruption to our services. We have limited phone lines and we may not be able to access your medical record so please bear with us.
"Please can we ask that if your call can wait, please telephone later.
"If you have an appointment please attend as normal.
"We will update you when we know more.
"If you need medical assistance or advice, please come into surgery or call 111.
"Thank you for your patience and apologies for the inconvenience."
NHS England said on Friday that the global power outage was affecting most GP practices.
A spokesperson said: “The NHS is aware of a global IT outage and an issue with EMIS, an appointment and patient record system, which is causing disruption in the majority of GP practices.
“The NHS has long standing measures in place to manage the disruption, including using paper patient records and handwritten prescriptions, and the usual phone systems to contact your GP.
“There is currently no known impact on 999 or emergency services, so people should use these services as they usually would.
“Patients should attend appointments unless told otherwise. Only contact your GP if it’s urgent, and otherwise please use 111 online or call 111.
"Work is ongoing to resolve the issue as quickly as possible. It is anticipated that the issue will lead to an increased demand on other services such as NHS111 and urgent treatment centres.
"Those who need urgent medical care should call 999 or attend A&E, especially in emergency and life-threatening cases when someone is seriously ill or injured, or their life is at risk. Please use NHS 111 online for all non-emergency healthcare needs.
"More information about when to call 999 and when to go to A&E is available via the national NHS website."
American Airlines said on Friday that none of its flights were taking off and the problems were due to an issue with Crowdstrike cybersecurity software.
In the UK, train companies have reported delays and said some of their information boards were not working due to IT issues.
Sky News live broadcasts were also affected.
Microsoft said, just after noon UK time on Friday, that the "underlying cause" of the mass IT outage had been fixed for its apps, but "residual impact" continued to affect some services.
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