A cough lasting more than a month is considered a chronic cough and needs proper evaluation rather than repeated self-medication, especially since medicines like Sinarest and Kufnil-DX have not helped; common causes include lingering infection, allergy, sinus drainage, asthma, acid reflux, or conditions like Bronchitis or Postnasal Drip. It is best to consult a doctor who may examine you and advise tests such as a chest X-ray or blood tests to find the exact cause, as treatment depends on the diagnosis (for example, inhalers for asthma, antiallergic medicines, acid-reducing drugs, or antibiotics only if a bacterial infection is confirmed). Meanwhile, stay well hydrated, avoid dust and smoke, use steam inhalation, and consider warm fluids to soothe the throat. Avoid taking repeated cough syrups without guidance, and seek prompt medical care if you have fever, weight loss, breathlessness, or blood in sputum.