Find out which cold and flu remedies work and which may be a placebo.
You can’t escape the jingles at this time of year for cold and flu remedies promising to “fight back at the first sign of sick”. Yet when you visit a doctor for the flu, why don't you leave with a prescription for Codral or Lemsip?
When we've looked at the evidence for cold and flu remedies, we've found it doesn’t always stack up.
Oral medications such as Codral contain a decongestant called phenylephrine. Companies’ claims phenylephrine may clear congestion rely on trials done 40 to 60 years ago. But only half of these trials showed phenylephrine was effective. Three US clinical trials published in the past decade concluded it was no better at relieving congestion than a placebo.
The evidence for common ingredients in cough medicines is similarly less than convincing. A 2014 study by the Cochrane Collaboration, which conducts systematic reviews on healthcare, cautiously concluded there was “no good evidence for or against” their effectiveness.
Six recent international clinical trials on over-the-counter cough formulations containing dextromethorphan or guaifenesin also did not demonstrate they work.
The only ingredient that’s got some backing is bromhexine. That said, the evidence is largely based on trials involving people suffering from long-term respiratory disease rather than a winter bug.
A 2015 Cochrane Review found taking a probiotic supplement in a tablet or dairy product appeared to halve the number of colds a person had and cut the duration of these bugs by nearly two days. However, the experts had misgivings about the quality of the trials and considered the evidence low.
Systemic reviews have found only one good-quality study showing garlic supplements lower a person’s risk of developing a cold. More research is needed.
Research has failed to demonstrate the vitamin offers any benefit in either prevention or treatment of winter bugs, beyond that of the placebo effect. The sole exception is for people under physical stress, such as high-performance athletes.
There is some evidence that regular use of these supplements can slightly reduce the risk a person will experience a cold. However, this benefit appears to be weak.
A standard cold or bout of flu is caused by a virus, not bacteria. Antibacterial additives will do little to prevent you from catching a cold or relieve your symptoms once you have one.
While sucking a throat drop will increase the flow of saliva and soothe your throat, you’d get the same effect from a lolly or a spoonful of honey. The anti-inflammatory and anaesthetic agents in some products may numb a painful throat, but their antibacterial ingredients won’t do anything to help cure your cold.
According to the US Centers for Disease Control and Prevention (CDC), it hasn’t been proved that antibacterial hand washes are any better at stopping the spread of infection than similar products without antibacterial chemicals. There’s also a risk they could boost antibiotic resistance.
Feel free to stick with regular tissues. Regular hand washing with soap and water, in and away from the home, and covering your mouth when you cough or sneeze are the best techniques to prevent transmission of common cold germs. The vaccine remains your best bet for avoiding the flu.
If you’re confused by all the claims, here are the products that may work.
These everyday painkillers can offer relief from the aches and discomfort of winter bugs. There’s more evidence paracetamol will relieve your bunged-up nose than the decongestant phenylephrine. You’ll also save money by sticking with the medicine-cabinet staple.
Studies suggest sprays with ipratropium bromide, such as Atrovent Nasal and Otrivin Plus, may offer relief from congestion, while oxymetazoline, used in Dimetapp, Drixine, Sudafed and Vicks Sinex, and xylometazoline, used in Otrivin, may also provide relief, albeit modest. Nasal sprays are also cheaper than painkiller-decongestant pills.
Antihistamines appear to offer some cold sufferers a short-term boost. If you choose an ordinary antihistamine pill you’ll pay, on average, $1.51 a day, compared with $5.40 for combination cold pills with an added antihistamine.
The jury is still out but there are small studies that have found honey can relieve symptoms and help children sick with the common cold sleep better.
University of Auckland medical professor Bruce Arroll says the best thing you can ask your doctor for is a sick note instructing you to take a few days off work. This stops you passing the virus to the outside world. There’s no cure for the common cold and most prescription medicines won’t offer anything more than a placebo effect.