For those of us in general practice, the arrival of December means only one thing: snot. Our surgeries echo to the sound of people coughing their guts up as they generously spread their germs further while waiting for a cure. Unfortunately, there's very little we can do to help. Because while science has enabled us to visit the moon, clone livestock and even pick up Channel Five through a terrestrial aerial, it's hardly been able to touch the common cold.

The simple reason for this, according to the Common Cold Centre at Cardiff University, is that colds are caused by more than 200 different viruses - devise a drug or vaccine to beat one and there are hundreds to take its place.

So the only treatments available for the foreseeable future are for symptom relief. Cold-busting is big business; the Proprietary Association of Great Britain (a UK trade association for manufacturers of over-the-counter medicines) estimates that sales last year reached £357m.

And according to a forecast from Beechams, in January 7 million bunged-up Britons will be shuffling to the pharmacy in search of something to make them feel better. But are these treatments worth the money? Or are they about as much use as the stuff you blow into your hanky?

Decongestants
A review published last year by the Cochrane Library, one of the world's foremost centres for evidence-based medicine, found that decongestant tablets containing pseudoephedrine improved symptoms for between three and 10 hours. And a review in the Lancet in 2003 also suggested that decongestant nasal sprays such as xylometazoline help reduce stuffiness.

However, there was no evidence of long-term benefit, and they need to be used with caution by anyone with diabetes, high blood pressure, hyperthyroidism, glaucoma, an enlarged prostate, liver, kidney or heart disease.

Antihistamines
These drugs more commonly pop up as hayfever and allergy treatments, but according to Clinical Evidence, a database that summarises what is known about more than 2,000 treatments, chlorphenamine (an antihistamine) can get rid of your runny nose and stop you sneezing in the first two days of a cold. Again there is concern about possible side effects - especially drowsiness.

Cough medicines
Most of us have had these poured down our necks at one time or other in the belief that the worse they taste, the more effective they are. Yet there is little proof that they do any good at all and a review in the British Medical Journal in 2002 showed that treatment with cough mixtures was no better than placebo in nine out of 15 studies.

Painkillers
Aspirin, paracetamol and ibuprofen can help with fever, headache, sore throat and muscle pains. They're all equally effective, but people prone to indigestion or with a history of stomach ulcers should stick to paracetamol - the others can cause irritation.

Echinacea
Questioning this herbal extract's ability to boost the immune system is tantamount to blasphemy - but that's what researchers writing in the New England Journal of Medicine did earlier this year when they produced a study showing that where rhinoviruses (a major cause the common cold) are concerned, it is little better than a sugar pill.

Vitamin C
Evidence from the Cochrane Library suggests that while taking regular vitamin C supplements does not offer protection against colds, it can lead to less severe and more short-lived symptoms. However, simply taking high doses of vitamin C as a cold kicks in is likely to have little effect.

Zinc
A study published in 1996 in the Annals of Internal Medicine, a prestigious American journal, generated interest by suggesting that zinc lozenges could shorten a cold by a whopping three days from the usual seven. Sadly, the killjoys at the Cochrane Library found no other evidence to support this and warned that these lozenges commonly cause mouth irritation, an unpleasant taste, nausea and diarrhoea.

The overall picture is disappointing, and while these remedies might help some people, you're generally better off saving your money. The best advice for those with a cold is simple: take regular painkillers, drink plenty of fluids, and curl up on the sofa with the remote control and a box of tissues until it passes. Oh, and unless you're really ill, keep your snot out of the surgery. And don't ask me for antibiotics.

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