We meet myriad people throughout our lives – at work, at school, at the gym – and while some of them turn into lifelong friends, others end up causing more harm than good. If you feel as though you're dealing with someone who might not have your best interests at heart, we're here to help.

We asked Susan Shapiro Barash, author of Toxic Friends: The Antidote for Women Stuck in Complicated Friendships (St. Martin's Press, 2009),to share some of the signs that you may be being used by someone who you thought was a friend.

1. You only hear from your friend when she needs something
"A friend who disappears untilshe is in need is fairly obvious in terms of being a user," says Barash."You don't hear from this friend until her boyfriend ditches her or she's out of a job." If your friend is only available when she needs your help – and is nowhere to be found whenever you could use some support – she's likely not the friend you hoped she was.

2. Your friend betrays your confidence for personal gain
One of the cornerstones of true friendship is trust. We need to feel we can confide in our friends knowingthat they won'tcast judgment or use our private information in a way that hurts us.

"She's not a real friend if you have confided in her and she betrays the confidence for her own gain," says Barash.

This could mean anything from flirting with a person you mentioned you were interested in or stealing your ideas and claiming them as her own in order to get aheadat work. "When your friend betrays your trust this hurts the heart of the friendship," says Barash.

3. Your friend makes plans with your friends – without you
If you include someone new among your group of friends only to find her trying to push you out of your own circle, you're likely dealing with someone who is using you, says Barash.

"If you run into this friend with your friends and she hasn't included you, it's not a good sign," says Barash.

Once could be excused as an oversight, but anything more is suspicious. "A friend who moves into your 'crowd' and pushes you out is toxic," explains Barash. "You get your new friend invited to a few events in town and the next thing you know she's throwing an event and doesn't invite you." Not only does this hurt, it also indicates that the person who you thought was a friend doesn't truly care about your feelings.

Page 1 of 2 -- Discover two more signs that you're being used and find out what you can do about it on page 2. 4. Her attitude toward you changes for the worse
One of the biggest red flags indicating that you're being used is having a friend suddenly do an about-face after getting what she wants.

"If she drops you or no longer respects you because she's gotten what she wants and no longer finds you valuable, she's likely using you," explains Barash. "Beware the friend who is so specific about her needs and hasn't any energy beyond that – such as a friend who wants to borrow your designer dress for a party she's going to and returns it in dishrag condition."

Borrowing the dress is normal friend behaviour, but returning it in poor condition indicates a total lack of respect, Barash notes.

5. She's insincere in her interest in you
We all ask questions and want to know what's going on in our friends' lives, but if someone you know is coming across asnosy and intrusive or doesn't seem sincerely interested in what you have to say, there's a good chance that person just wants something from you, warns Barash.

"A friend who is a user may dig deep for answers as if she cares, but really she's finding out what's in it for her," she explains."For example, she asks all about your daughter's new school only to be better prepared for her daughter's application there."

Barash shares some tips for what to do if you think you're being used:
• Wise up and turn the tables. Even if it isn't in your nature, start to consider what's in it for you in this friendship.

• Tell her how you feel. Call your friend out and say that you won't tolerate this kind of treatment from her. Be prepared for one of two outcomes: for the friendship to end or for the friendship to take a healthier turn.

• Rebuild and move forward. Try to respect one another and have a level of friendship beyond the using.

• Decide whether to stay or go. Decide what would happen if you let this friendship go. Would it harm you? Would you lose your foothold with your mutual friends? If so, it may be time to simply work on the good parts of the friendship and not be as invested in the using.

Not every one-sided friendship has to end, but if you feel like you're being used it's important to avoid being taken advantage of – so let your feelings be known. Real friends want the best for you, not just to benefit from you.

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