Hits & Myths: cough syrups

PUBLISHED : Monday, 19 May, 2014, 9:21am
UPDATED : Monday, 19 May, 2014, 9:21am

Q: Can over-the-counter cough syrups really kill a cough?

The straight answer: No

The facts: Over-the-counter cough medications are convenient for people who have no time to visit the doctor and are looking for immediate comfort from chest congestion and a sore throat. Many think that these cough syrups are the answer to clearing up a cough, but this is not the case, says Dr Cheng Chor-ho, a family physician from Town Health Medical Centre.

"Over-the-counter cough syrups cannot kill or inactivate the viruses that have caused the cough, nor can they suppress the cough," he says. "All they do is have a soothing effect on the throat."

Most cough mixtures bought over the counter contain cocillana, a herbal remedy to loosen phlegm; guaiphenesin, to relieve chest congestion; and phenylephrine hydrochloride, to relieve a stuffy nose and clear sinuses. They are mild medications that can help relieve the discomfort from a minor cough and the common cold.

"But really, the best treatment for these ailments and other simple upper respiratory tract infections is adequate rest, coupled with plenty of fluids. Over time, your symptoms should improve," Cheng says.

Prescribed cough medication is more effective at controlling a cough because it typically contains codeine, but the side effects are greater than if you were to take an over-the-counter variety. For example, you may experience dizziness, dry mouth, constipation, or even respiratory suppression if the medication is taken in high doses.

"Coughing is a reflex to help us clear any secretions, irritants, foreign particles and microbes that may be in our airway, so if you have a mild cough it's best to just ride it out instead of trying to get rid of it," Cheng says.

"Cough mixtures are useful if the cough is affecting your sleep as they help to provide temporary relief. However, it's important to note that prolonged use of these over-the-counter medications can be dangerous, as they may delay the diagnosis of serious illnesses such as asthma, chest infection and lung cancer."

So, while over-the-counter cough syrups are convenient because they save you a doctor's visit, it's important to stop taking them and to seek professional medical advice if your symptoms have not improved after a few days.