Choose your undies wisely - they could be affecting your health.

Author’s note: Don’t worry, there won’t be a single use of the word p**ties in this post. Aside from that one. Sorry.

Undies: they’re the first piece of clothing you put on in the morning, and they can also have the biggest impact on your health.

It’s true. That single decision you make while still half asleep could lead to some uncomfortable conversations with your GP.

Let’s start at… G.

1. G-STRINGS ARE BACTERIA HIGHWAYS.

A neat little G-string is the obvious choice for the gym, right?

WRONG.

While you might not have VPL (visible panty line), you could be putting yourself at risk of infection from bacteria that travels forward from your anus.

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As Dr Jill M. Rabin told The Huffington Post, “If you have a little bacteria – E. coli is the most common bacteria in the colon – in the back part of the fabric and you’re physically active, that material may move,” she said.

“All it has to do is move an inch or two and it’s next to the vagina or urethra. That thong may be depositing colonic bacteria into your vagina or urethra.”

2. WHILE WE’RE ON EXERCISE: FOCUS ON BREATHING.

Now that you have to run out and buy some workout knickers that cover your cheeks, make sure you choose something breathable while you’re at it.

Your sexy satin undies are a no-no, as they tend to trap moisture and therefore basically serve as a petri dish for yeast infections.

Listen: Mia Freedman recommends the best, Aussie-made period undies in the world. Post continues after audio. 

The best choices are, as you probably know, cotton or Lycra.

Regardless of the fabric, make sure you don’t leave them on for too long after your workout.

3. WHEN THE SUN GOES DOWN, SET YOURSELF FREE.

There’s nothing wrong with a set of soft cotton underwear, if you want to maintain a modicum of modesty under that nightie.

But going commando at night can be good for the vagina, particularly if you have a history of yeast infections, vaginal inflammation or vulvitis, as it allows time for the area to breathe.

Beware, though: if do you chose to follow your Basic Instinct make sure you’re not simply putting your vulva into contact with fabric and/or seams that are likely to cause friction and irritation.

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4. TOSS THOSE SAGGY OLD KNICKERS.

We’ve all got them – the saggy, stretched and faded pair we hang on to for a very specific, recurring reason.

Period undies, ladies. Period undies.

They might spare your fancy pants, but they’re not the best for your skin.

As dermatologist Sandra Lee told Women’s Health, “Chronic irritation and rubbing can cause abrasions that could go deep enough to cause darkening of the skin or permanent scarring,”she said.

“And sometimes, if your underwear is old, the elastic becomes exposed and can potentially give you a rash, called irritant contact dermatitis.”

5. IT AIN’T PRETTY. BUT THE BEST FABRIC IS…

So, you may think you already know the answer to this one… and you do. It’s still cotton.

Sorry to disappoint you, ladies.

When you hear the words “cotton undies”, you’re probably picturing something like this:

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While Cindy can clearly rock tighty whities like nobody’s business, anyone who’s been lingerie shopping lately knows that cotton underwear doesn’t necessarily mean granny undies anymore.

But don’t cheat:

“When patients say [to me], ‘But the crotch is cotton,’ my response is that the layer outside the crotch is not,” Dr Shieva Ghofrany previously told Huffington Post.

“Thus making the cotton less breathable and thus allowing more moisture to be trapped and more possible imbalance leading to infections.”

So what have we learned? Basically all cotton, all the time. Unless you’re feeling cheeky at night.