What is the best OTC cure for stopped up or stuffy noses?

Decongestants. Over the counter decongestants can help treat nasal congestion, but these medicines have significant side effects. Otc nasal sprays should also be avoided, as they usually end up doing more harm than good. There are prescription nasal sprays that are both safe and effective.
Saline rinses. Amazingly just plain salt water can be very effective in relieving stuffy noses. Available otc as a spray or as a wash, which can be very helpful. You can rinse several times a day with minimal to no side effects.