The Royal College of Nursing (RCN) said the problem will exacerbate health inequalities.
Delegates at the RCN’s annual congress in Glasgow will hear on Tuesday that diagnosis and treatment vary hugely across the UK.
Long Covid is treated by some clinics as a physical condition but mainly as a psychological condition by others, and existing services are woefully inadequate to meet the level of demand, according to the RCN.
Latest official data estimates that two million people are experiencing self-reported long Covid.
The RCN is calling for the Government to significantly increase its investment in research and care so that patients are treated fairly across the UK to prevent damaging health inequalities being exacerbated.
The RCN said it also wants nursing expertise to be used more widely to treat the condition.
The College said that, where nursing staff are used in long Covid care, they play a pivotal role in managing patient care and treating chronic symptoms.
The RCN’s professional lead for public health, Helen Donovan, said: “As nursing staff we see first hand how life-limiting long Covid can be, especially when patients are suffering with complex chronic symptoms such as fatigue, joint pain and brain fog.
“With over two million sufferers, there aren’t enough specialist services to meet the growing demand, and the help patients get varies hugely across the country.
“What’s clear is that the understanding nursing staff have of managing long-term conditions, including pain management, is not being used effectively.
“Ministers must significantly increase investment in long Covid research and support to ensure there are enough services and they are consistent across the UK.”