Most coughs after a cold are self-limiting and settle within a few weeks. A post-viral cough can linger for up to 8 weeks in some people without anything being seriously wrong.
You should arrange a medical review if a cough lasts longer than about 3 weeks, keeps getting worse, or is accompanied by warning signs: coughing up blood, persistent high fever, drenching night sweats, unintended weight loss, or increasing shortness of breath. These can point to conditions that need investigation, such as pneumonia, asthma, or other lung problems.
Call your local emergency number or go to urgent care immediately if you have severe difficulty breathing, chest tightness or pain, blue-tinged lips or face, or you are coughing up large amounts of blood.