Which medicine should I buy for cough?

What is the treatment of cough?
Drink warm beverages such as chamomile, flowers and anise,  hot soup
stop smoking
Take moxifloxacin 400mg once daily for 5 days
Take cetrizine 10mg once daily
take dextrometorphan syrup 10cc every 12 hours
take ventolin and bedosonide inhalers in case of allergic asthma
What are the causes of cough?
Smoking
some drugs
respiratory tract infections
Pneumonia
asthma
hypersensitivity
Lung tumors (rare cases)
What are the necessary tests in your case?
You should check with your doctor for a clinical examination
Chest x-ray
Full blood test