Health Check: do cough medicines work?

Having a cough can be distressing. It can disrupt sleep or even worsen urinary incontinence. So it’s not surprising 7% of Australians have reached for a cough or cold medicine in the last two weeks.

But with so many cough mixtures on the pharmacy shelves, it can be hard to know which, if any, product to choose.

What causes a cough?

The most common cause of acute cough is the common cold. Most people find symptoms of the common cold resolve within a few weeks.

Persistent coughs can be related to other health conditions, such as asthma or reflux. Coughs can also be a side effect of medications, including blood-pressure-lowering medicines known as ACE inhibitors. Because there are many potential causes of coughs, it’s important to seek professional advice for a cough that won’t go away or is worsening over time.

Dry versus chesty

Coughs are sometimes described as either dry or chesty. Dry coughs are irritating and itchy, and no mucus is produced. Coughs are described as chesty, wet or productive when mucus is coughed up.

Medicines included in dry cough mixtures are different to those marketed for chesty coughs.

Dry cough mixtures contain cough suppressants, which are supposed to act on the “cough centre” in the brain to reduce the urge to cough. Because cough suppressants such as dextromethorphan, pholcodine and codeine are derived from a group of medicines known as opioids, they can cause drowsiness or constipation.

Cough mixtures marketed for a chesty cough often contain expectorants and/or mucolytics. Expectorants such as guaifenesin are supposed to assist with loosening and coughing up mucus. Mucolytics such as bromhexine may thin the mucus in the airways and make it easier to cough up.

Are cough mixtures effective?

Cough mixtures will not fix the underlying reason for the cough.

Unfortunately, there aren’t many evidence-based options for relieving symptoms. A recent review of clinical trials found no strong evidence cough medicines are effective at relieving symptoms in adults. Only a limited number of clinical trials for each type of cough medicine were found and the clinical trials were often poorly reported.

You may find it helpful to keep hydrated and avoid triggers such as cold dry air and cigarette smoke. Inhaling steam while you are in the shower may help to loosen mucus in the chest.

Can I give cough mixture to my kids?

Australia’s medicines regulator, the Therapeutic Goods Administration (TGA), advises cough and cold medicines should not be given to children aged under six years. And consultation with a doctor, pharmacist or nurse practitioner is advised before giving cough and cold medicines to children aged between six and 11.

The TGA reviewed the use of cough and cold medicines in children in 2012. The review found only limited benefits with the use of cough and cold medicines in young children and they can cause side effects, especially if too much medicine is given accidentally.

Other products are marketed for treating coughs in young children, but there is little evidence these are effective. Cough syrups containing sucrose or glycerol as the active ingredient, with no other cough or cold medicines added, may be suitable for young children. But it’s unclear how effective they are at reducing symptoms.

There is not yet enough evidence about the safety or efficacy of ivy leaf extract (Hedera helix) for treating cough in young children.

Practical tips for choosing a cough mixture

If you do decide to take a cough mixture, read the labels carefully. Ask for professional advice if you have other health conditions, or are pregnant or breastfeeding, because cough mixtures are not suitable for everyone.

Cough mixtures can interfere with other medicines. The cough suppressant known as dextromethorphan, for instance, is not suitable for people taking some antidepressants because it can increase the risk of side effects.

Cough mixtures that combine an expectorant (to loosen and cough up mucus) with a suppressant (to reduce coughing) don’t make much sense. It’s best to avoid using a cough suppressant to treat a chesty, productive cough because reducing the urge to cough can make it difficult to cough up mucus.

Cough mixtures can contain other medicines for symptoms of the common cold, such as decongestants and antihistamines. It’s best to avoid using these combination products if a cough is your only symptom.

It’s important to measure the recommended amount of cough mixture using a proper measuring device. Check the product box to see if a measuring device is included. Purchase a device if you don’t have one at home.

Cold and flu tablets often contain cough suppressants. If you are already taking cold and flu tablets, seek further advice before taking a cough mixture. This will reduce the risk of taking more than the maximum recommended dose of cough suppressants.

If you have specific questions about cough medicines, ask your pharmacist for advice, check the consumer medicine information for a specific product, or call Medicines Line on 1300 633 424 (within Australia only).

Janet Sluggett has received funding from the Australian Commission on Safety and Quality in Health Care. Janet is a member of a national working group that makes recommendations about the advisory labels affixed to medicines when they are dispensed.