What causes long covid?

The exact cause is not the same for everyone. After COVID-19, the immune response, inflammation, blood vessels, nerves, breathing system, or energy regulation may remain disturbed. Some people notice fatigue, breathlessness, brain fog, sleep problems, altered smell or taste, pain, or symptoms that worsen after activity. Symptoms can fluctuate, so a better day does not always mean the problem has fully resolved.

Long COVID can follow a mild or severe infection, and some people may not have had a confirmed test. Other conditions can cause similar symptoms, so an assessment should consider the full history rather than assuming every new symptom is from COVID-19.

Keep a simple record of symptoms, sleep, activity, and triggers. Pace tasks by taking planned breaks before exhaustion arrives, and increase activity gradually only when the current level is tolerated. Regular meals, fluids, a steady sleep routine, and gentle movement may support recovery. Do not push through a marked symptom flare. A clinician can check breathing, heart rate, medicines, mood, and other possible explanations.

Seek emergency help for severe breathing difficulty, chest pressure, fainting, new one-sided weakness, severe confusion, or blue or grey lips. Arrange medical review for ongoing breathlessness, palpitations, substantial fatigue, unexplained weight change, or symptoms that limit daily activities. Urgent symptoms should not be attributed to Long COVID without assessment.

Ask which symptoms need examination or tests, how to pace activity safely, whether medicines or another condition could be involved, what warning signs require urgent help, and when follow-up should occur.