Thumb sucking, picky eating and nose picking are not only a nuisance, but they can have lasting effects on your child’s health.

Here, experts weigh in on why these habits are harmful and offer their best tips for how to deal with your child’s behaviors.

1. Hanging onto the bottle
Switching from a bottle to a sippy cup is often one of the most challenging things for toddlers to do. Plus, drinking too much milk can cause your tot to skip meals and miss out on calcium-rich foods like leafy green vegetables, yogurt and cheese and may even lead to iron deficiency.

Of course, allowing your child to fall asleep with a bottle in his mouth can also lead to cavities and tooth decay.

The American Academy of Pediatrics (AAP) recommends toddlers transition to a sippy cup by 15 months of age, but experts say the time to start introducing the sippy cup is around six months so that by the time they’re a year old, it’s gone for good.

“The truth is that they’ve satisfied most of their sucking needs by a year,” said Dr. Jane Scott, a pediatrician and neonatologist in Greenwood Village, Colorado, and author of “The Confident Parent: A Pediatrician's Guide to Caring for Your Little One--Without Losing Your Joy, Your Mind, or Yourself.”

Once your child has mastered the sippy cup and you think he’s ready, he can move on to using a regular cup without a lid.

2. Thumb sucking
It’s common for babies and toddlers to suck their thumbs or their fingers to soothe themselves. But depending on how intense they suck and how long the habit lingers, it can affect the way their jaws grow.

Since sucking depresses the tongue away from the roof of the mouth and compresses it, the habit can affect the normal growth of the upper jaw, causing it to develop narrowly and leading to a crossbite or an overbite, said Dr. Jade Miller, president of the American Academy of Pediatric Dentistry (AAPD).

Oral habits can also cause the upper teeth to be flared and the lower teeth to be pushed backwards.

The good news is that most kids will not have any problems. Nevertheless, you should bring your child in for regular check-ups with a pediatric dentist starting at age 1, or when the first tooth erupts, so the dentist can rule out any problems.

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You can help your child stop sucking his fingers with a special nail polish that tastes bitter, a cotton glove or a finger guard. Sometimes praising your child for not putting his fingers in his mouth and persuading him not to do it will be enough.

“In many cases, kids will stop on their own,” Miller said.

3. Picky eating
If you have a child who snubs his vegetables, refuses to eat anything new and only eats a handful of foods, it’s not only unhealthy for his growth and development but it can create a ton of stress in your home.

“Because kids eat multiple times a day, this becomes more of a stress point in the family dynamic than other problems,” said Dina Rose, PhD, a sociologist, parent educator and feeding expert in Jersey City, New Jersey and author of “It's Not About the Broccoli: Three Habits to Teach Your Kids for a Lifetime of Healthy Eating.”

Instead of pulling your hair out at every meal, the first step is to realize that your child is not being defiant just to be defiant, but that she needs the tools from you to be a healthy, adventurous eater.

Then, let your child explore a pea-sized amount of new foods so that she’s armed with information about new foods and will feel safe and empowered to eventually accept them.

Instead of asking your child, ‘Do you like it?’ ask what it smells, feels and looks like, for example.

“The goal becomes to teach children about food and not from a nutrition perspective but from a sensory perspective,” Rose said.

4. Nose picking
Whether you like to admit it or not, your kid probably picks his nose. Kids usually pick their noses when they have boogers and it can become even worse when they have a cold, congestion or allergies.
It might be unsightly to you, but the only time it can become more difficult to deal with is if it causes frequent nosebleeds, said Dr. John P. Dahl, a pediatric otolaryngologist at Riley Hospital for Children at Indiana University Health in Indianapolis, Indiana and an assistant professor of pediatrics and otolaryngology at Indiana University School of Medicine said.

Help your child to wipe and blow his nose regularly and remind him to keep his fingers out of his nose. If your child has a cold or infection, a salt water saline spray or gel can clean out his nose and moisten the lining. For babies and toddlers, a bulb syringe can help too.

5. Teeth grinding
Between 14 and 20 percent of children grind and clench their teeth, a disorder known as bruxism. Children will usually grind their teeth at night, but it can also happen during the day, and it’s common when new teeth come in or when children have stress and anxiety.

In fact, preschool-age children who grind their teeth are more likely to be withdrawn and have problems in school, according to a study presented at the 2008 SLEEP conference.

Children who have large tonsils and adenoids and who have obstructive sleep problems are more likely to have the habit too.

“Some kids will grind by shifting their lower jaw forward to keep their airway open,” Miller said.

The good news is that it’s rare that grinding will become so severe that treatment is necessary. If you suspect your child has obstructive sleep apnea, you should have your child seen by his pediatrician. And if grinding affects your child’s permanent teeth, his dentist might recommend a mouth guard.

6. Snacking all day
Allowing your child to eat every time he asks not only creates a power struggle, but it teaches your child that temporary hunger must be quelled fast. Grazing all day long, especially on sweet, salty and crunchy snacks, also means your child won’t eat their meals because they’re not hungry.

“Those experiences push kids away from the healthy foods that we’re trying to get them to eat,” Rose said.

Instead of allowing your child to graze all day, decide on a meal and snack schedule. At snack time, offer fruits and vegetables.

“It teaches them in their mind that fruits and vegetables are the go-to food, not the exceptional food that we just serve at dinner,” she said.

7. Prolonged pacifier use
The pacifier is soothing for your child and studies show it may reduce the risk for SIDS. Yet it can also be a breeding ground for germs when your child puts it back in his mouth after dropping it or taking it out. Prolonged pacifier use can also increase the risk for ear infections, lead to dental problems, and may affect language development, Scott said.

Although putting an end to the pacifier is much easier to do than thumb sucking because you can get rid of the object, when it’s time to do so it can still be hard for your child to let it go.

When your child starts to walk, it’s a good idea to limit the pacifier to naps and bedtime to keep it clean and limit the time he uses it.

When you’re ready to put an end to it for good, you can ask your child to pack it up in a box and give it as a gift for another baby. “They feel like they’re doing something special. Often they feel like , ‘Ok, I can’t get it back because this baby needs it,’ Scott said.