It could be tempting when you see your friend pull out that perfect shade of lipstick out of her make-up bag or that powder brush you prefer to borrow (rather than get yours).

What you don't know is that some of these beauty products are totally unsafe to use. Even though the person you are sharing these products with may not have a visible cold sore, they may have other bacteria that could be passed off to you.

Here are 5 beauty products you should steer clear of sharing:

1. Pressed foundation

Dry powders don't hold onto bacteria, but that doesn't mean you can't transfer bacteria from one person to another, this is possible if you're using a sponge to touch up areas around your mouth or eyes. The only safe way to let your girlfriend use your pressed powder, should she need to touch up her shiny forehead in a 'Selfie emergency', is to spray the powder with an alcohol-based spray (like a cosmetic sanitizer mist) and then give her a clean makeup brush to use and have her swipe it over pressed powder once.

2. Make-up brushes

It feels great to use your friend's powder brush because it bring your make-up to perfection (Wrong!). While acne is an internal skin condition, you can get break-outs  by using someone else's brushes and cross-contaminating bacteria. The only safe way to share your brushes, is to use a fresh brush or spray your used brush with alcohol to kill bacteria or shampoo them weekly (and then condition them so they last a long time).

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3. Mascara

Do you use your mascara and sometimes feel like you are about to have a boil on your lid? What most ladies are not aware of is that, your favorite mascara can harbor bacteria and viruses that are easily transmissible, like conjunctivitis. Since your eyes don't have the same layers of protection that your skin does, it is more susceptible to infections like pink eye (Commonly known as 'Apollo").

Also, each time you pull the wand out and push it back in to lube up the brush head, you push air into the dark bottle's base, feeding the aerobic bacteria that can survive in an oxygenated area. The only safe way to share your mascara, if you so desire, is to practice what pro makeup artists do and never let the wand that comes with it be used; use only disposable wands to apply it, and never double dip.

4. Razors

Most people know this already but for those who are not aware, it is totally wrong to share razors. Razors are important to not share, even though stainless steel doesn't carry bacteria for very long, you can still transfer warts or genital herpes,if you or your friend has either by someone using your razor or by using someone else's.

Even worse, razors can cut you and draw blood or fluids, which leave bacteria on the blade after rinsing, making you more vulnerable to a staph infection, hepatitis, or blood-borne viruses (like HIV, although it's highly unlikely).

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5. Lipstick or balm

Lipsticks and balms are the commonest beauty product shared but they are a hard no to sharing unless you stash an alcohol spray or wipe in your purse to sanitize them. A large percentage of people carry HSV-1 (Herpes simplex virus 1,which is ubiquitous and contagious). But because it is in your system doesn't mean you ever show signs of it externally. This is referred to as asymptomatic shedding, where you have the virus but you don't show any symptoms, it is all based on your immunity and whether or not something like stress can trigger an outbreak.

That is why it is so important to use your own lip products, because if you pass your favorite lipstick around from girl to girl and you or your friend has the virus, you could be transferring bacteria or HSV-1 and never know it. And then you won't know if you have the capability to develop a cold sore of fever blister until you have it, which is unfortunately too late.