In some cases, a bout of sinusitis can continue for more than 3 months- this is known as chronic sinusitis. Some people who suffer from chronic sinusitis continue to have mild symptoms on an ongoing basis, with flare ups of acute sinusitis from time to time. Serious complications of acute sinusitis are rare, but can include meningitis, cellulitis (skin/soft tissue infection), and spread of bacterial infection to other parts of the body.