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Deutsch (EUR)Long COVID: Symptoms, Diagnosis and How Long It Can Last
Long COVID: Symptoms, Diagnosis and How Long It Can Last
After SARS-CoV-2 infection, some people experience symptoms that persist, return or first appear after the acute infection has resolved.
Author: Ing. František Kokoš and colleagues · Updated: 25 October 2026
How does WHO define post-COVID-19 condition?
Under WHO’s clinical case definition, post-COVID-19 condition occurs after probable or confirmed SARS-CoV-2 infection, usually around 3 months after its onset. Symptoms last for at least 2 months and cannot be explained by another diagnosis. They may persist from the initial illness or appear after an initial recovery. [1]
Why are thresholds of 4 or 12 weeks also used?
NICE uses the following time categories. These clarify terminology; they are not instructions to delay seeking medical assessment until a particular time has passed. [4]
| Time since the start of illness | Term |
|---|---|
| Up to 4 weeks | Acute COVID-19 |
| 4 to 12 weeks | Ongoing symptomatic COVID-19 |
| More than 12 weeks | Post-COVID-19 syndrome, when symptoms are not explained by another diagnosis |
What symptoms may occur with Long COVID?
Reported symptoms include fatigue, worsening after exertion, breathlessness, palpitations, pain, difficulty concentrating or remembering, sleep problems, dizziness and changes in smell or taste. Symptoms vary between individuals. A symptom list alone is not enough to establish a diagnosis. [1, 3]
What is post-exertional malaise (PEM)?
PEM means a worsening of symptoms after even minor physical or mental exertion. According to CDC, it may develop 12 to 48 hours after activity and last for days or weeks. [3]
How is Long COVID diagnosed?
Assessment includes a discussion of the history of symptoms, a physical examination and targeted tests when needed. No single test can reliably confirm or rule out Long COVID. Normal results from routine investigations do not, on their own, mean that symptoms are absent. A clinician also considers other possible causes. [3]
Can it develop after mild COVID-19?
Yes. Long-term symptoms can develop after a mild infection or after a period of apparent recovery. [1, 3]
Why does Long COVID develop?
The causes are not fully understood. Several biological mechanisms are being studied; research findings cannot be reduced to one cause that applies to everyone. [1]
How long can post-COVID-19 condition last?
Symptoms may persist for months or longer. Some people improve gradually, while others experience fluctuating or recurring symptoms. The time criteria used to define the condition do not predict when a particular person will recover. [1, 3]
What does care for Long COVID involve?
Care is tailored to each person’s symptoms and limitations. Priorities, activity tolerance and the need for further assessment or rehabilitation can be discussed with a clinician. A record of symptoms and activities may help this conversation. This article does not recommend products or approaches with a promise of curing Long COVID. [2, 3]
When should you seek medical advice?
Assessment is appropriate if problems persist, affect everyday functioning or include new unexplained symptoms.
Frequently asked questions about Long COVID
What is Long COVID?
Long COVID refers to long-term symptoms following SARS-CoV-2 infection. The exact time criteria depend on the definition used. A clinician assesses the diagnosis while considering other possible causes.
What are common symptoms of Long COVID?
Commonly reported symptoms include fatigue, worsening after exertion, breathlessness, palpitations, cognitive difficulties, sleep problems, pain, dizziness and changes in smell or taste.
What is PEM?
PEM is a worsening of symptoms after physical or mental exertion. It may appear after a delay and persist for days or longer.
Is there a test for Long COVID?
No single laboratory or imaging test can definitively confirm or rule out Long COVID on its own.
Can Long COVID develop after mild COVID-19?
Yes. Post-COVID symptoms can develop after a mild acute infection.
How long can Long COVID last?
Symptoms may last for months or longer. The course varies between individuals and may fluctuate; the exact recovery time cannot be predicted in advance.
Key points to remember
Long COVID is a long-term health condition following SARS-CoV-2 infection that may affect several body systems. It is not diagnosed using a single test.
Expert sources
