There is no definitely defined condition relation between the two but the chronic inflammatory markers in sinusitis can have an impact on the bowel symptoms also further IBS is more die to stress so the mental and physical stress due to the chronic sinusitis symptoms may be aggravating ua ibs symptoms. The treatment of both are different while chronic sinusitis mainstay of treatment is steroids mostly local and sometimes systemic, the IBS can be handled with alosetron, rifaximin, chollordiazepoxide etc. u need a thorough consultation with physician and lot of relaxing exercises.

Both are inflammation.. CRP and esr tests