There are three different 'types' of long Covid-19, researchers have said.
Experts from King's College London said that there appears to be three "subtypes" of the condition, each with their own set of symptoms.
Researchers examined 1,459 people living with long Covid-19 - defined by the study authors as suffering symptoms for at least 84 days after infection - who were taking part in the Zoe Health study.
The pre-print of the study, published on medRxiv, claims that people with long Covid-19 appear to be split into three main groups.
The first one includes those with neurological symptoms including fatigue, brain fog and headache - most commonly found among those who became infected when the most dominant strains were alpha and delta.
A second group experienced respiratory symptoms including chest pain and shortness of breath. This was found more commonly among those infected during the first wave of the virus.
A final group are experiencing a diverse range of symptoms including heart palpitations, muscle ache and pain, and changes in skin and hair, King's College said.
But researchers said these three subtypes were evident in all variants.
Clinical lead author Dr Claire Steves, from King's College London, said: "These data show clearly that post-Covid-19 syndrome is not just one condition, but appears to have at several subtypes.
"Understanding the root causes of these subtypes may help in finding treatment strategies.
"Moreover, these data emphasise the need for long Covid-19 services to incorporate a personalized approach sensitive to the issues of each individual."
First author Dr Liane Canas, from King's College London, added: "These insights could aid in the development of personalized diagnosis and treatment for these individuals."