The Cough Goes On…And On…And On…

As the mercury in the thermometer dips lower, more and more people are visiting the hospital with cold and flu symptoms. In addition to their sore throats and runny noses, many patients complain of having a persistent cough that is downright annoying. It is equally frustrating to doctors who have to treat these lingering coughs.

What is a cough?

Coughing is a reflex much like sneezing or a knee jerk when gently tapped. When our respiratory tract encounters an irritant (infection, foreign object, allergies, etc.), the nerve receptors inside the lining of our airway send a signal to the cough control center of our brain. The brain, in turn, sends back a signal to trigger a cascade of events leading to a cough. First, we inhale to fill the lungs with air, the voice box closes and then the diaphragm and respiratory muscles contract to quickly increase the pressure inside the lungs to be greater than the ambient air pressure. Next, the build-up of pressure forces the voice box open, and air escapes rapidly from the lungs with the goal of dislodging the irritant from the respiratory tract. The cough reflex is meant to clear the air passage of foreign objects or of excess fluids; it helps clean and protect the respiratory tract.

Coughing during a cold

Coughing is a normal biological reaction to colds. Cold viruses cause infection and inflammation of the respiratory tract and result in increased mucus secretion. Coughing functions to clear this excess mucus to keep the airway clear so that you can breathe normally. Coughing also serves as a vehicle for cold viruses to propagate. “Newborn” viruses packed inside phlegm and air droplets get coughed out of the host body and have a chance to infect another person. Coughing can propel these air droplets as far as a meter. Even if the cold viruses don’t find an immediate host, they can remain highly contagious for between three to seven days outside a host if the conditions are right.

Exposure to these viral particles in sufficient quantities usually results in an infection. You can inhale these virus-packed air droplets if you are in close proximity to a person with a cold. Therefore, wearing a mask can sometimes help reduce your risk of catching or spreading a cold. You can also catch a cold by introducing the virus into your nose or eyes when rubbing them with virus-contaminated hands. Therefore, hand-washing is an easy and effective way to control the spread of colds or other infectious diseases.

Acute vs. chronic coughs and their causes

Coughs can be classified by their duration. Acute coughs last up to three weeks while chronic coughs last longer than three weeks.

The most common causes of acute coughs include:

• Infection of respiratory tract (caused by the common cold, bronchitis, pneumonia, the flu, etc.)
• Post-nasal drip (caused by colds or allergies)
• Emphysema

The most common causes of chronic coughs include:

• Smoking
• Post-nasal drip
• Asthma (especially in children)
• Acid reflux
• Respiratory tract infection
• Chronic bronchitis
• Blood pressure medicine containing ACE inhibitors
• Pertussis (whooping cough)
• Post-infection hyper-responsive airway

Of all these causes, coughing as a result of respiratory infections is probably the most annoying because there is no foolproof way of getting rid of the cough. Generally, colds cause about two or three weeks of coughing, but some people inexplicably experience a cough that can last for a few months. These people usually have no fever and experience improvement with their other cold symptoms, but the cough remains. It usually manifests as a dry cough that only occurs when they lie down at night and when they get up in the morning and/or on-and-off throughout the day.

These patients often feel a tickle in their throats or a sensation in their chests that prompts them to cough. Sometimes, the coughing fits can be severe and last for a few minutes, causing them to experience headaches, sweating, dizziness, incontinence or even a rib fracture. These people are otherwise feeling well with normal energy and appetite. They just have a persistent cough that is disruptive to work and, sometimes, to sleep.

People with this type of persistent cough visit the doctor’s office more frequently. They often have normal blood tests and chest X-rays. They usually have tried a couple of different kinds of antibiotics without relief. Sometimes, they seek TCM, acupuncture, massage or Chinese medicinal scraping treatments. Typically, nothing seems effective. Eventually, after a period of unsuccessful treatments, the cough goes away by itself.

To medicate or not?

So, what can be done? What kind of medicine should be taken, or should medicine be taken at all? Treatment for coughing must address the cause. Most coughs are caused by acute respiratory infections. Because these infections are caused by viruses, antibiotics are not helpful (antibiotics kill bacteria, not viruses). The exception is the flu, which can sometimes be treated with an anti-viral medicine if diagnosed early. Otherwise, my best advice is to rest and wait it out.

Cough suppressants or expectorants can be used to relieve symptoms, but they do not hasten the recovery process. Also, they often prove useless. Many patients simply don’t find them effective. Partially for this reason, cough and cold medicines, such as Robitussin or Tylenol Cold, are no longer recommended or available to children under 6 in the United States because their potential side effects outweigh the actual benefits.

Common cough medicines

Finally, I’d like to briefly discuss a few cough medicines commonly prescribed by western-trained physicians. Dextromethorphan and codeine are two common cough suppressants. These drugs inhibit the cough center of the brain and make the relevant neural receptors less sensitive. The main side effects, especially for codeine, are drowsiness, constipation and nausea. Additionally, long-term use may lead to addiction. These two drugs are usually mixed with guaifenesin (an expectorant).

As a reminder, antibiotics are NOT cough suppressants. Unless the patient has bacterial bronchitis or pneumonia, antibiotics are NOT indicated in treating coughs related to common colds or the flu and might even result in harmful side effects. Misuse of antibiotics may also lead to bacterial resistance.