Saline washes. Acute sinusitis symptoms are similar to an upper respiratory infecion but more severe and includes purulent drainage with sinus and facial pain. It lasts longer than the usual 7-10 days of a normal cold. Saline washes or lavage are very helpful along with topical and oral decongestants. Occasionally antibiotics are needed if the saline washes and decongestants aren't helping.
Acute sinusitis. Salt water washes two to three times per day to start. Consider adding a decongestant if you are plugged up. Most acute sinus issues are viral, so antibiotics are used after 5-7 days typically. Lastly, there is debate if using an oral antihistamine will thicken up the mucus, so that is entirely your decision.