Why are you on Levo? Are you Hypo or hyper? I asked my doctor after my TT if my allergy meds were OK to take, he said it was fine. The concern with the thyroid is if you are hyper, the cold meds will increase your heart rate and BP making hyper worse.
I myself cannot take any otc meds anymore....I seem to react to all of them. So now I use saline rinses and all natural nasal sprays if needed.