What's the best otc medication for nasal congestion due to sinusitis infection?

Just the opposite: Sinusitis or inflammation of the paranasal sinuses (there are 4 paired sinuses) does not cause nasal congestion. The opposite is true. That is, nasal congestion leads to sinus inflammation. It is true that they very often occur together, but the nasal congestion is the first event. Otc treatment may include saline (salt water) irrigations of the nose, a netti-pot and a decongestant.

Pseudoephedrine: The best treatment for a bacterial sinus infection is antibiotics - to kill off the infection and let the sinuses heal. For viral infections, decongestants can help with the symptom of nasal congestion. Pseudoephedrine, available without a rx from your pharmacist, works best, but often produces significant side effects. Oxymetazoline nasal spray also works well, but don't use it for more than a wk.

Sudafed: Sudafed 30 mg tablets is what i recommend to my patients. Usually tell them to take 2 every 6-8 hours to get the most relief.