There can be various reasons for a chronic cough, which have to be evaluated. Every possibility is assessed with respect to risk factors that may be present for that condition. Although You have not mentioned details such as your age, the nature of cough, type of cough, any factors/time of day you have more cough, any other medication(for some other condition) you are taking etc.Yet few of the reasons a patient may be having long lasting cough can be Bronchial asthma- In this the patient has dry cough, usually at nights and associated with difficulty in breathing and wheeze. Chronic bronchitis can be another cause for chronic cough, although it is more common in smokers of middle age & elderly,still non smokers may also develop it due to various other risk factors.In This the cough is present for more than 2 years usually and cough is associated with sputum. Some people suffering from Gastro-esophageal reflux disease(GERD) can also have chronic cough ,but they will report symptoms associated with dyspepsia as well. Certain medicine such a Angiotensin Converting enzyme inhibitors used in patients of Hypertension may cause dry type pf chronic cough. Certain infections of lungs such as Tuberculosis can cause Cough that is associated with sputum, fever, Weight loss, decreased appetite, some times blood in sputum. So In my view you need to be evaluated for the cause as per your detailed history and examination by a pulmonologist so that it cane be properly treated.