Cat has an URI. Has anyone uses Little Noses?

Hi there. My cat has been sick since last Thurs with an URI. I've already been to the vet and have been prescribed some antibiotics. He seems to be getting better but still is really congested. The vet said I should get these pediatric drops called Little Noses. It comes in a saline form and a decongestant form. I'm not sure which one I should get? I called and left a msg for the vet so I'm waiting for her response. Has anyone had luck with either? Thanks!