Top immune myths, busted by experts

Health myths have a sneaky way of sticking around. Some of these myths were somewhat logical, though not based in fact.  For example, laying inside the carcass of a whale was once thought to bring relief to rheumatism sufferers. Fortunately, this treatment was quickly disproven.

When it comes to your immune system, there’s a lot of confusion out there—so we’re cutting through the noise. Let’s set the record straight on some of the biggest immune myths still doing the rounds.

Myth: Cold weather makes you sick

First, let’s talk about correlation vs causation—yes, these science-y terms matter, especially when we're chatting about cold weather and getting sick.

Continuing the marine theme, let’s say there’s a bunch of penguins wandering around a street. Not long afterwards, there’s a power loss on the street. If we assume the penguins caused the power loss, that’s causation. But if we assume the penguins just happened to be there at the time of the power loss, then that’s correlation. Both are logical conclusions, in a way.

But unless there’s an army of evil penguins scheming to take over the world, only one is correct. It’s much more likely that the penguins were going for a leisurely walk, and the power loss happened because of something else.. Penguins didn't cause the power loss. Their presence just correlated with the power loss.

The association of illness with cold weather is the same. Historically, cold weather has been associated with more illness. But, is it the drop in temperature that causes illness, or are there other factors that play?

What the science says

Some of the science suggests that, maybe, we get ill in cold temperatures because of overcrowding. Things like the cold and flu are transmissible bugs. When we’re close together, we’re at more risk of giving each other those bugs. And, what do we do in winter? We like to stay inside, having more contact with each other in enclosed spaces, moving between spaces in the community.

Interestingly, the transmission of many viruses dropped during the COVID-19 pandemic, potentially because we didn’t move around each other as much and  adopted cleaner practices.

While that may be the case, some authors have suggested that there may be other factors, as well, like our upper airways drying up, lowering their defences against bugs like the flu. Mucus, after all, is a defence mechanism.

In a nutshell, while cold weather may correlate with more illness, it’s not the cause.

The best thing to do for avoiding and spreading illness in winter is to wash hands, maintain safe distances if we’re sick, and keep ourselves as healthy as possible otherwise.

Myth: Going to bed with wet hair will give you a cold

Wet hair and catching a cold may also be a question of correlation and causation. Historically, wet hair may have been correlated with catching a cold. Many loving grandparents have given us advice on keeping hair dry to avoid catching that cold.

What the science says

The common cold is caused by a virus – rhinovirus. Have you ever seen those expandable magic balls? Through a powerful microscope, rhinovirus looks like that. These sea urchin-like bugs get into our nose, infect the airway, then cause the illness we know as a common cold.

What's the best way to avoid and not spread a common cold? It's the same old boring advice. Wash your hands, maintain a safe distance when sick, and stay otherwise as healthy as possible with good health habits.

Myth: You don’t need the flu vaccine if you’re healthy

Let’s not beat around the bush. There’s an ocean of conversation about vaccines. It raises passions. 

Some literature notes that immunisations date back to the 12th century, in China. Those days, they used the pus from an infected patient's body to vaccinate people against the smallpox virus. In essence, they were trying to encourage the body to generate protection from the disease. 

This is what vaccines are intended to do. One way or another, they’re intended to encourage our bodies to generate an immune response, so that when the real bug comes, our bodies can fight it with the natural defences that have been created with the encouragement of a vaccine.

What the science says

Public health specialists, among others, have worked long and hard to figure out which vaccines are useful for which people. Over the years, they have generated the body of evidence about what works well for who and where. This is an important point. We are all different human beings, with different bodies, different histories, and different backgrounds.

In Australia, doctors, nurses, and pharmacists are trained to provide vaccinations. A good way to find out what is best for you is to talk to one of these healthcare professionals that you trust.

Myth: Antibiotics can cure colds and the flu

A 2017 study found that about 5.97 million respiratory tract infections in Australia were managed with at least one antibiotic annually. It's not uncommon for people to go to the doctor and ask for an antibiotic for their cold. 

What the science says

Most of the time, antibiotics are not necessary. This is because many respiratory tract infections are caused by viruses, not bacteria. Antibiotics are designed to fight bacteria. They will simply not work against viruses. Our bodies are very good at fighting against many of these viruses. All we need is time backed by healthy habits.

Certainly, antibiotics have saved millions of lives since its development. The overuse is leading to resistance, preventing their use in lifesaving situations. Therefore, cautious use is important. Using them for the cold and flu, is not the proper use for antibiotics

Myth: The flu is a just a bad cold

The common cold and flu are different, but often used interchangeably in our day-to-day language. Sometimes, sure, the flu may just feel like a bad cold. But, is it that simple?

What the science says

The common cold, traditionally, is caused by the rhinovirus. The flu is caused by influenza. Having said that, it may be difficult to differentiate our respiratory symptoms from these two bugs, and other respiratory bugs, just based on how we feel. In fact, often, unless we do a test, we won't know what bug hit us. And, those bugs often change, mutating and evolving.

The way we experience symptoms from these illnesses can change every time, just like the bugs themselves. Still, some bugs like influenza and Covid have been associated with more severe illness in the past.

The bottom line

The sage advice? It's the usual stuff. Adopt healthy habits. Have a good diet, exercise, wash your hands, see your trusted healthcare professional, intervene medically when necessary, and let your body do the rest.

Reviewed by the Healthylife Advisory Board June 2025.