Sinusitis develops when the mucous-membrane-lined cavities in the bones of the face become infected. Although the same family of viruses that typically cause the common cold (rhinoviruses) also cause sinusitis, not all colds are accompanied by sinusitis, and many cases of sinusitis don't involve other cold symptoms. First, an upper respiratory tract infection causes blockage of tiny sinus drainage openings called ostia. Once clogged by infection or excess mucus, the sinuses can't drain, and invading bacteria cause the sinus walls to swell and fill with pus.

Aromatherapy can help reduce sinus blockage. James Duke, PhD, recommends adding a few drops of essential oils of eucalyptus, peppermint, tea tree, thyme, lavender, or pine to a pot of boiling water. Hold a towel over your head as you carefully breathe in vapor rising from the pot. (Do not put your face directly over the boiling water or steam.) The vapor released by the oils relieves congestion.