A cough lasting six months is considered chronic and requires a proper medical evaluation to find the root cause, rather than just masking the symptoms. Over-the-counter cough syrups containing cough suppressants and antihistamines only offer temporary relief and will not cure the underlying issue, which is why your cough returns. Common, manageable causes for this include cough-variant asthma, acid reflux, or post-nasal drip.I advise against self-medicating with these temporary syrups. Please consult your doctor or a specialist. They can run simple tests to identify the exact cause and prescribe a targeted, effective treatment plan to help you recover fully.