Sponsored Topics. Marshfield is a city in Webster County, Missouri, United States. The population was 5,720 at the 2000 census. It is the county seat and part of the Springfield, Missouri Metropolitan Statistical Area. Marshfield was settled in 1830.
Another common cause of sinus headaches is allergic rhinitis (hay fever). Both prescription and nonprescription (over-the-counter, or OTC) oral medications â antihistamines, decongestants and corticosteroids â are used to treat it. 1  Antihistamines.
Sinusitis, or sinus pressure and congestion, can be caused by allergies. Taking an over-the-counter antihistamine, such as ClaritinÂ®, ZyrtecÂ®, or their generic equivalents, can help to control the allergic response and relieve the symptoms you are experiencing.