Why Do We Catch Colds When the Weather Changes?

General Medical

Dr. Sam Hay

If you live on the east coast of Australia, Sydney in particular, then you’ve suffered the wrath of the weather gods since early March.  It’s been wet – very wet. But what set this weather pattern apart was the way it snuck up on us – all of a sudden we said farewell to sunny days spent outdoors, forced to welcome endless days cooped up indoors. But it wasn’t just boredom and frustration we endured.  Within days of the rains setting in, the sniffles followed suit. 

Cold season was upon us!

The cold hard facts are: colds and flus are spread by close contact with others.  Drive everyone indoors with inclement weather, especially for weeks on end, and you’re asking for trouble.

The little nasties – viruses – invade our upper respiratory tract, triggering mucous and snot production, coughs, sore throats, and sneezes. At every cough or sneeze, tiny droplets of virus laden snot particles spread out around us. Not only does your mate innocently breathe them in if you don’t cover up properly, these tiny droplets land on every surface in sight. Waiting patiently for the next person to infect.

There are many myths, old wives tails, and sure-fire cures for the cold. 

But just what are the facts when it comes to the common cold? 

Firstly, lets look at what treatment options are available once you have a cold.

There is no cure for the cold, there is no drug or potion you can take that will kill the virus any faster than your good old immune system. So really, all we are left with is trying things that help make you feel better.

Pain relief - Paracetamol and NSAIDS (non-steroidal anti-inflammatory drugs eg ibuprofen) are as good as each other at relieving symptoms such as a sore throat and general aches and pains. But, they don’t have any effect on coughs or nasal discharge.

Antihistamines and decongestants - Both of these options provide some benefit for some people, it really seems to be ‘horses for courses’. Looking at the evidence, they seem to work best in combination. But once again, they’re just relieving symptoms.

Nasal spray decongestants - Offer some benefit for some, but MUST be limited to a couple of days use as rebound nasal congestion can occur.

Humidified air/vaporisers - Look, these can improve symptoms of congestion, but they make no difference to how long the cold lasts for.

Zinc - This one’s a hard one. There’s quite a bit of evidence showing it’s effective in reducing cold symptoms, however, it comes with some risks. Nasal spray options must definitely be avoided – it can permanently kill your sense of smell. Zinc should really only be used in consultation with your doctor or at least a pharmacist.

Antibiotics - Completely useless. Antibiotics target bacteria, colds are caused by viruses.

Antiviral drugs - Well if antibiotics are no good, surely antivirals work, don’t they? Well, it’s not that clear cut. Further research is required, but at this stage there’s no great benefit from these drugs at all for the common cold – just not worth the hassle, cost, and potential side effects.

Vitamin C - A natural option I hear people cry! People who take Vitamin C every day, have shorter cold illnesses – by 8% - but does that really make a difference? If a cold lasts five days, does a nine hour shortening really help? Some would argue yes. One big problem is: Vitamin C only works if you are on it every day before the cold starts.

Echinacea - This is another hard one, as it’s one of the other natural options people bang on about. Sure, there are some studies that say it’s great, but they’re balanced by just as many studies that say it’s no better than taking a jelly bean (placebo) each day. Suffice to say, it’ll do no harm, but it’s most likely a waste of money.

Can I take anything to stop me getting a cold in the first place?

Most prevention strategies for the common cold have focused on the use of vitamins, minerals, herbs, and lifestyle changes. However, no vitamin or herbal potion has been conclusively proven to effect your chances of getting a cold.

The simple things do work, so practice what you preach!

  • Cover your nose and mouth when you sneeze or cough.  No tissues? Then use your elbow.
  • Wash your hands when you’re done.
  • Keep away from sick people, but most importantly, keep away from others when you’re sick!
  • Avoid sharing drinks, foods, and utensils with the sick ones around you.

Probiotics - More research is required, but early (low quality) data tells us that probiotics probably do decrease your chances of getting a cold. Once again, they won’t do any harm.

Exercise - Another tricky one as pooling all the medical research together isn’t much help. In summary, there does seem to be some trends towards a positive benefit.

Vitamin D and E - In short, there’s no conclusive evidence at all.

Herbal products - I’m sorry grandma, but there’s just no evidence anything works, and that includes garlic….

Can you catch a cold from the flu shot?

No! Lets set a few things straight on this one. Firstly, the ‘flu shot’ protects against influenza, a particular type of virus, causing a debilitating illness that can be fatal for many, especially babies, pregnant ladies, the elderly, and those already very unwell. The vaccine we get each year is very effective against protecting us against influenza, but it doesn’t protect against common colds whatsoever.

Some people after the flu shot can expect to feel a little achey or unwell for a day or so after, but it shouldn’t impact on daily life at all. The reason a lot of people end up with a cold after they get the flu shot is because we’re giving these shots at the time of year when colds and flus are more common. So it’s a coincidence thing, and nothing to do with the shot.

Does playing outside with wet hair cause the cold?

This has to be one of grandma’s favourite winter warnings doesn’t it? “Dry your hair before you go outside Johnny”, or “Don’t play in the rain kids, you’ll catch a cold!” Being outside with wet hair won’t magically give you a cold! This one’s more about the time of the year – the colder months are when there are more colds and flu viruses flying around. What about wearing a singlet then? Again, there’s nothing magical about a singlet. 

The bottom line is, if you’re getting very cold and wet for a long period of time, your immune system isn’t going to be quite as good. So your grandma is kinda right, but only when things are extreme!

Can a cold virus really travel through the air?

Do a quick YouTube search and you’ll find amazing clips in slow motion of people coughing and sneezing. The gross bit about them is you can clearly see clouds of tiny snot particles billowing out up to three metres away! This means viruses are spread a lot further that we realize, reinforcing the need to cover up when sneezing, and wiping down surfaces regularly – all in the name of preventing unwanted virus spread.

Does a good nights sleep make a difference?

There’s no doubt a poor sleeping pattern contributes to the likelihood of you getting sick with a cold.  A solid functioning immune system relies on the body getting plenty of rest.  In fact, one study found that those getting less than five hours of sleep a night were 3x more likely to get a cold than those getting more than seven hours of sleep a night!

BMedSci, MBBS(Hons), FRACGP, GDipSpMed, DCH
Director Your Doctors®


Please note: Dr. Sam's blog is general advice only. For further information on this topic please consult your healthcare professional.

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