A method for irrigating a paranasal sinus may involve advancing a distal portion of a sinus irrigation catheter through an ostium of a paranasal sinus into the sinus and passing fluid through multiple ports disposed at different locations along a length of the catheter distal portion into the sinus. A flexible irrigation catheter device for irrigating a paranasal sinus may include: an elongate catheter body having a proximal end, a distal end, a lumen therebetween, and a tapered distal portion extending proximally from the distal end of the catheter body; a proximal hub coupled with the proximal end of the catheter body for connecting to a source of irrigation fluid; multiple side ports disposed along the catheter body closer to the distal end than the proximal end and in fluid communication with the lumen; and a distal end port at the distal end of the catheter body.