Feeling short of breath has a wide range of causes. Common ones include anxiety or panic, deconditioning, asthma, allergies, chest infections, and anemia. Longer-term breathlessness can relate to conditions such as COPD, heart problems, or being overweight. It often helps to note when it happens — at rest, on exertion, or lying flat — as this guides the cause.
See a doctor if breathlessness is new, getting worse over days or weeks, limits your activity, or comes with a chronic cough, wheeze, ankle swelling, or fatigue. People with known heart or lung conditions should report any change.
Call your local emergency number for sudden severe breathlessness, breathlessness with chest pain, blue lips, an inability to speak in full sentences, or breathlessness with a swollen, painful leg (which can suggest a clot). A clinician can assess and arrange tests. This is general information only.