5 Lies Parents Should Never Tell Kids.

It’s not uncommon for parents to lie to their children — “the tooth fairy left you money” — but lies that stem from frustration or are meant to coerce, or sometimes even protect a child, can backfire.

And while kids may not always understand that they’ve been lied to, according to Kirsten Cullen Sharma, a neuropsychologist at NYU Langone Child Study Center, the goal for parents is to model healthy communication.

After the cut are common lies parents tell their children and why they don’t work.

“It won’t hurt”

If your child fears the dentist or getting a shot at the doctor’s office, assuring him the experience will be painless may come from a protective place, but, “It doesn’t help a child deal with difficult or uncomfortable situations and could even [compound his fear the next time],” Sharma tells Yahoo Parenting. “It’s important for parents to create an environment where the child feels safe to share their feelings openly.” Try validating his fears with supportive phrases such as, “I know you’re scared” or “You look sad,” which encourages him to open up. You can also prep kids for scary moments in the future by showing them photos of medical tools or with role-play exercises.

“Everything is going to be all right”

It’s inevitable that children will feel frightened by the world around them, whether it’s from experiencing a tragedy firsthand or watching the news. Instead of providing them with a false sense of security, view these events as age-appropriate opportunities for an honest dialogue. Then offer assurance that resonates: “I will do everything I can to take care of you,” “This is very sad, and you can share your real feelings with me,” or “I love you, and we will do everything we can to get through this together.”

“I would’ve never done that at your age”

This comment can feel particularly critical, even if it’s not true, because it creates a sense of comparison between a parent and a child. “Parents are often trying to have a teachable moment when they say this, but it doesn’t feel that way to children,” says Sharma, who adds that a direct approach — telling your kid you’re upset and disappointed by his actions — is a better learning lesson.

“That’s it — I’m leaving you here”

You’d never leave your kid in a public place, but threatening to do it is superscary to a child and doesn’t solve the problem at hand. Sherma recommends allowing him to choose the consequence for his bad behavior. Try, “You can either walk out of the store with mommy now, or I will carry you out” or “You can either walk out of the store with dad right now, or you will not have a play date.”

“You are the best!”Your kid may be the number one in your eyes, but labeling him the “best” at anything (student, sports player, pianist) is often untrue and can have a surprisingly negative effect on his self-esteem. One study published in the Journal of Experimental Psychology found that exaggerated praise causes kids with low self-esteem to feel ashamed if they perform poorly in the future. Focusing on the effort your child put into a task, not the outcome, will keep him motivated. Use such phrases as, “You worked so hard to solve that math problem” or “I loved all the energy you put into your performance.”