Don't share your makeup. Seriously.

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Unless you’re hell-bent on catching herpes simplex, you’d avoid laying a smacker on someone with a cold sore, right?

But you probably wouldn’t think twice about sharing your lipstick or lipgloss with a girlfriend on a night out.

RELATED: Here’s how fast germs go from the toilet to your desk to your mouth

Sure, sharing is caring, but there are a few big no-nos when it comes to potentially germ-infested beauty products and tools. Here are the six you should avoid sharing. Just say no.

1. Tweezers / nail clippers / nail files.

The thought of unsterilised nail clippers or tools at the nail salon is enough to turn you off your pedicure, but the same goes for sharing beauty tools with friends. If the person who used it before you had any kind of cut or open wound, chances are you’ll get bacteria, fungus or a nail infection as a result.

It’s only worthwhile to double check the tools at your local nail bar uses proper sterilisation methods, otherwise you could end up with a hepatitis C or staph infection. No $20 pedicure is worth that.

2. Lipsticks and lip glosses.

Your mouth is a breeding ground for bacteria as it doesn’t have the same epidermal layer of skin the rest of your face does. As lip gloss is more moist than lipstick, viruses like herpes simplex 1, which is responsible for cold sores, can live in the sticky gloss and be spread by the applicator.

3. Mascara/eyeliner.

Any eye makeup product like mascara, eyeliner and eye pencils are not a good idea to share as they come in close contact with the eye membranes. The obvious potential infection here is conjunctivitis, but a bottle of mascara can also house herpes simplex and keratitis (an inflammation of the cornea). Since a person can remain germy for weeks after the infection has cleared up, pass on sharing your wands and pencils.

RELATED: The most germ-ridden object in your house is not what you would expect 

4. Moisturisers/masks/anything that comes in a jar.

Some of my favourite skincare products come in jars, but dipping your bacteria-chocked fingers into the jar is only going to lead to a transference of the bacteria from your hands in to the jar. Which you then smear all over your face. To avoid this, ask your friends to use a cotton tip to get the product out (and do this yourself too).

5. Antiperspirant.

Sure, it’s not technically a beauty product but if you’ve found yourself at a friend’s place or at work in need of some roll-on, stop. Germs, bacteria, fungi and ew, yeast can all be transferred on a roll-on antiperspirant stick. Spray on deodorant on the other hand? Totally fine.

RELATED: There’s another reason you shouldn’t be reusing disposable water bottles

6. A facial cleansing brush.

Sharing your expensive sonic facial cleansing brush with your sister or flatmate seems like a sensible economic solution, but not when you think about all the dead skin cells floating on the bristles. Do you really want those to settle in your open pores? Didn’t think so. By all means share your device, but use your own cleansing pad – and change it regularly (every three months is enough).

What’s also out? Earphones, earrings, toothbrushes, razors and hairbrushes. You might come across as a total germaphobe to your friends, but at least you have less chance of getting sick this year.

And if you really didn't want to offend them, you could always go for a matching tattoo...? Separate needles, of course.