Bunk

"It's my sinuses, doc . . ."

I can assure you, 100 years ago, maybe only 60 years ago, no one going to the doctor described their chief complaint as "sinus." The concept of a sinus infection, or sinusitis, or even the existence of the paranasal sinuses themselves was not something the general public held at their fingertips. In those good old days, common folks would summarize their upper respiratory syndromes as a cold or the grippe or ague or catarrh or influenza. Or they might give a symptomatic description (which is what doctors really want to hear), such as a runny nose, a fever, sore throat, cough.
Then in the late 1950's and early '60's, paralleling the rise of otolaryngology ("ears, nose , & throat") as a surgical specialty, people started seeing animated heads with outlines of the paranasal sinuses on just about every third TV commercial. Suddenly, the poor little sinuses bore the blame for every aggravated episode of stuffy or runny nose, and sinuses became part of our national consciousness. And every over-the-counter cold concoction known to man had to have the word "SINUS" emblazoned on its label to be considered a serious medicine.
But before I get to explaining the truth, let's see what you readers out there know about the "sinus" concept that you constantly invoke in the presence of your doctor. Take the SINUS QUIZ:

1. What does the word "sinus" mean?
2. Where are the sinuses?
3. Why are they there?
4. What's in the sinuses?
5. How does it get there?
6. How can you tell if the sinuses are infected?
7. What's the best way to treat it?

Give yourself a point for each correct answer. 4 is a passing grade. Don't worry, you probably failed.

Here goes:
Those sinuses are cavities, open spaces -- that's what the term means -- in your skull. They're there because air is lighter than bone, and a skull made of solid bone would put a powerful burden on our neck muscles. Therefore there are airspaces in the frontal bones (above the eyebrows), the maxillary (cheek) bones -- OK, you knew that -- but also directly behind the nose (ethmoid), behind the eyes (sphenoid), and behind and above the ears (mastoid). Even the middle ear (internal to the eardrum) is a kind of sinus cavity. Yes, we are all airheads -- at least, we're supposed to be.
The air that fills the sinuses, of course, comes from the outside. All the skull airspaces get air from openings in the nose, three in each nostril, plus the internal auditory canals (Eustachion tubes) to the middle ear, which open in the post-nasal passage. The openings are only about a 16th of an inch wide, but enough to let air flow in and out constantly.
Lining the inner surface of the sinuses is a living membrane identical to the moist inner surface of the nose. It secretes a thin layer of mucus and contains cells with little filaments (cilia) that move the mucus along, as well as immune-system cells which secrete histamine in response to allergic stimuli or other noxious things in the air.
If the air openings get blocked, the air in the sinuses gets slowly absorbed by the membranes, while the mucus builds up. Since the whole system is open to the outside, bacteria can potentially get in and, given three or four days, multiply within the goo to the point of causing a pressurized pocket of pus.
Looking at a patient's face, peering in the nose, pressing or tapping on the facial bones or shining a bright light across them cannot really tell a doctor if the sinuses are clogged (even though we commonly go through these motions). Certainly, hearing the patient complain about a clogged or runny nose, a pain in the head or face, feeling run down, feverish, etc. etc, etc. doesn't mean the sinuses are not functioning well. The only reliable way to tell if a sinus is abnormally clogged (short of sticking a sinus endoscope into them) is to get an xray, preferably a CT or MRI scan (which are often faster, much clearer, and not much more expensive than plain xrays).
Furthermore, clogged sinuses may not be infected, but rather partially occluded by a thickened inner membrane, in the same way the nose itself reacts to allergies. And if infected, the infection may be with viruses, which do not respond to anti-bacterial antibiotics, and generally get better without treatment in 7-14 days. Although this last point has been debated by researchers for at least 2 decades, the latest and most reliable studies indicate that only about 5% of upper respiratory infections involve pathogenic bacteria in the sinuses.

Even though 95% of people with any form of cold think they need an antibiotic for their sinuses.

What they need is to make sure the mucus is flowing, because any build-up of infected fluid in a body cavity needs to drain in order to heal. The commonly-used cold-symptom medications all contain a decongestant -- these days the behind-the-counter-but-not-needing-a-prescription pseudophedrine -- which makes mucus less liquidy, thus making the nose feel drier.
This, of course, is a terrible, TERRIBLE way to treat sinus congestion, because it virtually guarantees that mucus will be too thick to flow. By the time patients call me for their "sinus infection" each and every one of them has been taking these worthless preps, from Nyquil to Dayquil to XYZ-Cold-and-Sinus-D (Non-Drowsy Formula!), and have successfully converted a transient annoyance into a sub-acute misery.
What helps mucus flow? Drinking enough fluids helps. Tea, hot soup, or just inhaling some steam is useful. A sterile salt-water nasal spray can be of some benefit, while decongestant sprays (Afrin, etc), plain-old camphor (Vap-O-Rub) or ammonia-based sniffers cause too much irritation to the mucus membrane to help in the short run, and will worsen the condition if used too long.
Guaifenisin, an iodinated compound taken orally, will help if taken in large enough quantities. It's the active ingredient of all expectorants, such as Robitussin, but you'd have to drink an entire 4-ounce bottle of the stuff every day to get a therapeutic dose. Better to take a few concentrated (600 mg) guaifenisin tablets such as Mucinex daily for a week or two.
(NOTE--combinations of guaifenisin and pseudophedrine, which you'll find everywhere, don't make sense and don't work. Plain guaifenisin is what you want.)
When the nose is running -- no matter if the mucus is clear, yellow, green, brown, or bloody -- the sinus cavities will stay aerated. When you try to dry up the runny nose, you risk clogging up the sinus.
If the mucus membranes are thickened by constant nasal allergies or a series of rapid-succession viral colds, the best remedy is a cortico-steroid, either by a long (weeks or months) course of nasal spray or a short (a week or less) course of pills. They cool down the inflammation and shrink the swollen tissues without drying up mucus. Used properly (which means, by the way, NOT injecting them with a needle into the nose) they are virtually harmless, but I've had the hardest time convincing some patients of that. Lots of folks wouldn't think twice of taking pseudophedrine, which is far more dangerous and ineffective, than the steroid that would help them because of an irrationally-perpetuated fear of steroids.
And finally, remember that tobacco and, yes, even marijuana causes the cilia which push mucus along, to stop working, and when that smoke gets up into the sinuses (which it will), the mucus stagnates, just as it does in the depths of a smoker's lungs. Don't complain to me about your sinuses if you're smoking or putting other substances up your nose.
So don't blame the poor sinuses for every headache or cold you get. Don't use Sudafed or anything like it, take some plain Tylenol or ibuprofen for the headache, drink some tea, take some Mucinex if you have to, and go right ahead and blow that nose. Don't ask for unnecessary antibiotics, don't be afraid to take properly-prescribed steroids, get the CT scan when your doctor orders it. The next time you provide a chief complaint say something like "My head hurts and my nose runs"; stay away from the S-word.