A cold is an upper respiratory
infection that is caused by any number of viruses. It generally goes away
on its own in 7-14 days, and antibiotics are not indicated, since they
act against bacteria and not viruses. The symptoms of a cold, such as
nasal congestion, runny nose, etc. are primarily from the effects of the
viruses on the lining of the nose, which is called mucosa. However, one
of the problems with trying to tell the difference between a cold and
a sinus infection is that the lining of the sinuses is similar to the
lining of the nose. Thus, a cold virus will often infect the mucosa of
the sinuses as well as that of the nose. In fact, it has been proposed
that the standard medical term for a cold (“rhinitis”, meaning
“inflammation of the nose”) would be more accurate if it were
changed to “rhinosinusitis”.
In contrast to a viral cold, when people use the term “sinus infection”,
they usually mean a bacterial infection confined primarily to the sinuses.
A bacterial infection differs from a viral infection in that it generally
produces more inflammation, and often draws millions of the body’s
white blood cells to help combat the infection. The white, thick discharge
that is typical of a bacterial infection (but rarely seen with a viral
infection) is in fact composed of dead bacteria and white cells. The body’s
immune system will usually control a bacterial infection, but it may take
longer than controlling a viral infection and is sometimes not entirely
successful. For example, studies have shown that about two-thirds of bacterial
sinus infections will eventually resolve on their own, but 1/3 will require
antibiotics to become completely eradicated.
Why is it important that we should try to distinguish between a viral
cold and a bacterial sinus infection? The most important reason is the
overuse of antibiotics. While antibiotics may or may not be used for bacterial
infections, they should never be used for viral infections. Thus, every
time a patient gets an antibiotic for a viral cold, it increases the risk
of that patient developing an antibiotic-resistant infection in the future.
Also, it’s expensive…a ten-day course of many antibiotics
can run over $100.00.
So, since both viral and bacterial infections can occur in the sinuses,
how does one tell them apart? Since both share many similar symptoms (see
below), there is always a bit of guesswork involved, and sometimes sinus
x-rays or even a CT scan of the sinuses may be helpful. The first step
is an educated patient, who goes to the doctor when appropriate and understands
that antibiotics may not be necessary, at least not initially. The following
information is thus presented to allow you, the patient, to make a more
informed decision as to when to become concerned that you may have a sinus
infection. Further information may be found on this website in the sections
Sinusitis and Sinus Headaches.
|Symptoms That Can Be Seen
With Either a Sinus Infection or a Cold
1) Nasal Congestion
Since both cause swelling of the nasal mucosa, nasal congestion can be
seen with either a cold or a sinus infection.
2) Colored Nasal Discharge
It is definitely not true that colored nasal discharge means you have
a sinus infection. Towards the end of many viral colds, the nasal discharge
changes from clear to colored (usually green) because of a change in the
thickness of the mucous the nose makes. True pus, such as is seen with
pure bacterial infections, is usually white or yellowish-white and is
thick like cream.
3) Postnasal Drip
Postnasal drip is usually not the result of too much mucous being made,
but rather mucous getting too thick. The normal nose makes up to one quart
(!) of mucous a day, and ordinarily it is just pushed to the back of the
nose and swallowed. When we become aware of it, it’s because it
has gotten too thick to be easily swallowed, and “hangs up”
in the back of the throat. Since both viral and bacterial infections can
make nasal mucous more thick, both can thus cause a sensation of postnasal
Fever is caused by our body fighting off an infection, and can also be
seen with either viral or bacterial infections. A fever of less than 100
degrees is usually not significant, even if your usual body temperature
runs less than 98.6 degrees.
5) Facial Pressure and Pain
Although we don’t know what actually causes these symptoms, the
most likely cause is probably swelling of the mucosa in the sinuses. Since
by now you should know that both viral and bacterial infections can cause
this type of swelling, it should come as no surprise to also know that
these symptoms can be seen with either a viral or bacterial infection.
|How to tell the Difference
Between a Sinus Infection and a Cold
The length of time you’ve been sick is probably the most reliable
way to tell if you have a viral cold or a bacterial sinus infection. Most
colds are gone or at least starting to improve by ten days. If your symptoms
haven’t started to improve by day 10, or if you’re getting
worse after 7 days, it’s more likely that you have a bacterial infection.
Also, the most common way that a bacterial infection starts is following
a viral cold, since the cold virus weakens the sinuses ability to defend
themselves against bacteria. Thus, if you have a cold, start to get better,
and then get even sicker, you may have what is called a “secondary”
2) Symptoms On Only One Side
Most cold viruses affect all of the nasal and sinus mucosa equally, which
is why you don’t get a cold on just one side of your nose. Bacterial
infections, on the other hand, can involve one to several sinuses, sometimes
just on one side and sometimes on both sides. Thus, if your symptoms such
as nasal congestion, pressure, etc. are exclusively on one side, it is
more likely you have a bacterial infection.
3) Tooth Pain
Pain in the upper teeth is suggestive of a bacterial infection.
|Other Tests That May Be Considered
This is a procedure in which a small telescope is used to examine the
inside of the nose. It cannot be used to look into the sinuses themselves
(unless you have had previous surgery to open the sinuses), since the
natural openings are so small. However, it can determine whether any pus
is coming out of the opening (indicating bacterial sinusitis) or, conversely,
if the opening looks normal. Since these scopes are quite expensive, they
are usually only used by ENT specialists.
2) Sinus X-rays or CT Scans
These studies are more useful in determining whether chronic symptoms
(those lasting months rather than days or weeks) are due to sinus problems,
but are sometimes used to differentiate between a cold or bacterial sinusitis.
Looking at the images of the sinuses that either produces, sinus mucosal
thickening can be seen with either a viral or bacterial infection, but
an air-fluid level or opacification of a sinus (the whole sinus is filled
with pus or fluid), is suggestive of a bacterial infection.
3) Bacterial Cultures
These are not helpful, as billions of bacteria are present in the healthy
nose, and if you stick a culture swab in the nose, some bacteria will
always grow in the culture. In fact, some unscrupulous ENT physicians
use these culture results to convince patients that they have a “chronic
sinus infection” and then recommend unnecessary sinus surgery.
|Distinguishing a sinus infection
from a cold is difficult even in the best of circumstances. This is largely
because many of the symptoms popularly associated with the diagnosis of
“sinusitis” can in fact be seen with viral infections as well.
In general, a visit to the doctor is not indicated until you have been sick
for at least seven days, since until then, there is little to distinguish
between a cold and a sinus infection.