It might help, but I would need to know more about the nature of your cough to say for certain. Any number of factors can trigger coughs. An acute cough — one that lasts fewer than three weeks — is usually the result of an upper respiratory infection, such as the common cold or the flu. Coughing can also be a symptom of COVID-19. Chronic coughs are those that last longer than eight weeks. Their causes include gastroesophageal reflux, postnasal drip, allergies, and asthma, as well as repeated exposure to irritants such as pollution or cigarette smoke. Less commonly, lung cancer, sarcoidosis, or chronic obstructive pulmonary disease is responsible for a chronic cough. Certain blood pressure drugs, such as ACE inhibitors, can also be to blame. Before attempting to treat a cough at home, you should see a health care provider to determine the cause, especially if it lingers for more than a few weeks or if you think you may have COVID-19.
Mullein is most useful for addressing a dry cough associated with a cold or the flu. (Productive coughs — meaning those expelling mucus — should not be treated.) This common roadside weed (Verbascum thapsus) is a member of the snapdragon family. Its large, downy leaves have long been used in folk medicine to treat bronchial and respiratory conditions. More recently, research suggests that mullein possesses anti-inflammatory properties and helps relax muscles in the respiratory tract, which may explain why some people find that it relieves coughs. Look for tinctures of mullein online or in health food stores; the adult dose is a dropperful in warm water every four hours. Alternatively, you could sip a cup or two of mullein tea, plain or flavored with honey, lemon, or cinnamon. One of word of caution: Because safety data is lacking, children should not be given mullein.
Andrew Weil, M.D.
Niaz Ali et al., “Anthelmintic and relaxant activities of Verbascum Thapsus mullein,” BMC Complement Altern Med, 2012 Mar 30. doi: 10.1186/1472-6882-12-29