Chronic cough for 4-5 months what could it be?

A few common things: The most common causes for a chronic cough in an otherwise healthy (american) person are gastroesophageal reflux, postnasal drip/allergies, and asthma. In endemic areas/populations, TB is also a major concern. Other problems including COPD and cancer, tend to occur in people with risk factors. Generally a brief visit with exam can reveal the likely cause or any need for further testing.

Possibilities...: Major possibilities include bronchospasm, gerd, chronic sinusitis, chronic bronchitis or some combination of these. To determine the precise etiology and thus the treatment needed, see your doctor for evaluation. You may need some testing to figure out what is causing your cough and to get you on effective treatment. Meantime, quit smoking if you are currently smoking! good luck!