Thank you for your question. Cough is a reflex meant to protect your airway from an irritant (e.g. mucous, foreign bodies or virus/bacteria). When persistent, it is usually a symptom of a condition. A cough lasting longer than 8 weeks is called chronic cough.
Common causes of chronic cough in children include problems arising from the nose and sinuses (e.g. allergic rhinitis, sinusitis), lungs (e.g. asthma, bronchitis, foreign bodies) or stomach (acid reflux).
The treatment of cough depends on the underlying cause. Since you mentioned that your daughter has been diagnosed with sensitive nose (Rhinitis), it is important to ensure that she has been compliant with her nasal steroid sprays for the treatment to be effective. Nasal steroid sprays work by reducing inflammation of the nose and sinuses and this can take up to 2 weeks before you notice significant improvement in nasal symptoms.
Postnasal drip (mucous flowing from the nose and sinus down the throat) can be a persistent irritant to the voicebox (larynx), causing it to be inflamed and swollen.
The voicebox is a very sensitive organ. Once infamed, it is prone to causing symptoms such as feeling of something stuck in the throat (globus sensation), itchy throat with frequent throat clearing, cough, hoarse voice, sore throat and clear phlegm.
Inflammation of the voicebox can take time to settle down. Apart from mucous from the nose and sinuses, acid reflux from the stomach can also be a source of irritant to the voicebox.
Your daughter can visit an ENT Specialist who can help optimize the treatment of her sensitive nose and exclude other problems in her upper airway that is causing a persistent cough (including sinusitis although this is less common in children).
If your daughter has other symptoms from her lungs such as shortness of breath or wheezing, she may need to visit a Respiratory Physician (Lung Specialist).
Although over the counter (OTC) cough medications (e.g. dextrometharphan, guaifenescin, antihistamines,codeine etc) may help ease cough in some children, a Cochrane meta-analysis (a summarized analysis of high level studies) has concluded that they are no more effective than placebo (medications with no cough suppresant properties) and may have potential side effects (e.g. drowsiness and insomnia).
In fact, 1-2 teaspoons of honey a day has been shown to be as or more effective than some OTC cough medications and with excellent safety profile (in children older than 2 years old).
Having said that, it is still more important to find out the reason for the cough and treat the underlying cause accordingly.
Hope this helps and all the best.
