It's that time of year when many people reach for cough medicines, but research indicates that home remedies work just as well and that some medications can delay recovery from chest infections.

Most cough medicines merely provide a placebo effect, which may help calm coughing children but does not curtail the illness.

The Australian consumer affairs magazine Choice says some cough medicines contain more than one active ingredient, such as those marketed as both an expectorant and cough suppressant. But it warns that using a suppressant for a chesty cough could delay recovery because suppressing coughs can increase the risk of serious lung infection.

The magazine's findings were based on articles published in the British Medical Journal, the Cochrane Review and research by the World Health Organisation.

The British article - by Tom Fahey, a senior lecturer in general practice, and Knut Schroeder, a training fellow in health services research - found that over-the-counter cough medicines could not be recommended for acute coughs because there was no evidence of their effectiveness.

Choice magazine, published by the Australian Consumers' Association, says it is widely accepted in the medical community that the medicines are not useful.

That means the thousands of dollars of cough medicine sold in New Zealand each year provide little more than a psychological benefit.

However, New Zealand Asthma and Respiratory Foundation medical director Professor Ian Town said cough medicines could be helpful for mild coughs.

Although an element of the placebo effect was associated with cough medicines, they did contain ingredients which suppressed coughs, so benefits were not all imagined.

But for anyone with a serious chest infection, a cough medicine, particularly a cough suppressant, was not what was needed.

Professor Town said people could decide to take the medication instead of seeing a doctor - a delay which could cause a serious chest infection to develop. He said anyone with a lingering chest infection not responding to cough medicine should see a doctor because they could have a serious condition such as pneumonia.

Choice says many medical specialists recommend that children should not be given cough medicine, especially those with cough suppressants, which can cause side-effects such as drowsiness and balance problems. They can also increase the risk of serious lung infection, especially if the child is asthmatic or has a long-term lung condition.

Other ingredients such as antihistamines can cause coughs, and decongestants such as pseudoephedrine may cause irritability, sleeplessness and problems with muscle tone.

New Zealand pharmacists generally advise against giving cough medicine to children under 2. Some of the medicines contain alcohol. Children's formula mixtures are available with lower concentrations of ingredients provided for older children.

Where cough medicines can work is because people think they are helping.

Choice says that just because cough medicines are no better than a placebo does not mean that they do not help. Placebos with a similar consistency to a medicated product may also work to some extent.

The magazine says people could just try a non-medicated product such as a glycerine-based syrup, a spoonful of honey or a hard lolly to suck on.

They are cheaper and similarly effective.

There are two main types of cough medicine - expectorants to thin and loosen the mucus in the chest and cough suppressants which are used for calming dry, unproductive coughs.

Choice says there is little medical evidence that expectorants work. The magazine recommends drinking plenty of fluids, which will thin mucus and make it easier to clear.

It says suppressants should not be given to children.

If symptoms are bearable, says the magazine, people are better off saving their money (cough medicines range from just under $5 to over $10 in New Zealand supermarkets) and treating their cold or flu the old-fashioned way - by drinking plenty of fluids and resting.