Coughs and Sneezes

As everyone says now days, Winter is coming.

And with it the inevitable batch of coughs and colds.  Bacteria and viruses spread around the place by people acting as incubators and distribution centres for illnesses we could all do without.

But how does your body protect itself against the invasion of these nasties? What is the difference between a cough and a sneeze and why might you never look at an escalator in the same light again?

Everybody knows that coughs and colds can be airborne.  This is why we are all told to cover our mouths when we cough or sneeze, to help control the spread of the infection. So what lines of defence does our body put in place.

The chosen site of infection is the respiratory system – the way we get air into our bodies to supply us with oxygen.  This route starts at our nose, passes backwards to the rear of the throat where it joins up with the oral cavity.  From there is passes down through the pharynx and larynx and into the trachea, our air pipe.  This tube’s shape is maintained by semi circular ridges of cartilage.  There is no cartilage at the back so that the oesophagus (food pipe) can expand to allow food to pass down into our stomach.  The whole system is lined with special cells that produce mucus.

Whether this mucus is called snot or phlegm depends on whether it is produced in the nose or in the lower respiratory tract.  Where ever it is produced, its purpose is to engulf any particles that shouldn’t be in the air passages.

Once the invading particle has been engulfed, how does it get up out of the trachea?  The cells that line the trachea have cilia; little hairs that beat to waft particles away from the cells.  Within the trachea the beating of the hairs is coordinated so that mucus is passed from the lower cells up towards the larynx where it can be disposed of by swallowing.  This system of moving the mucus from the depth of the lungs to the throat is known as the mucociliary escalator.  It gives all the defeated bacteria and viruses a ride up to the waste disposal route.

So what makes us cough and sneeze?

The respiratory system also has sensitive hairs within it that detect things that should not be there.  If these hairs are triggered in the lower respiratory tract then a message is sent to the diaphragm causing it to contract rapidly and expel air from the lungs.  This is a cough.  If the nasal passages are irritated then it causes a rapid expulsion of air through the nose – a sneeze.

Why does the cough persist?

The presence of foreign particles in the airway, their attempt to invade cells, and coughing, can cause the lining in the airway to become inflamed. This inflammation can be a good thing as it is caused by an increased blood flow to the area which brings increased levels of immune system components, but it does tend to linger for a few days after the initial infection or irritation has gone.  This will resolve itself but if it continues beyond a few weeks you should see your doctor.

Does a cough syrup help?

Cough syrups vary in their active ingredients.  Some contain drugs that suppress the cough reflex.  Think about that.  It stops your body from trying to remove foreign particles from your airway!  Some contain decongestants that make your mucus more runny, easier to cough up.  Most contain sugar.

No systematic study of cough medicines have shown that they have any effect on coughs (either good or bad).  Continue to administer your favourite cough syrup if you want but be aware what you are administering is the placebo effect.

 

Alternative cough treatments

When you have a cough or cold your body increases the amount of mucus that it makes.  This can be around 2L a day so you need to make sure you drink a lot of fluid.

You can decongest your airways with a hot shower.  Damp warm air will make it easier for you to breath.

Honey or lemon (or a hot toddy) will be as effective as any cough syrup. (All of which are as effective as doing nothing so just do what makes you feel good.)