Tantrums and excessive crying in a toddler may be a sign that something's wrong.

Drastic Changes in a Toddler's Behavior

by Beth Greenwood

Toddlers seem to change or learn something new every time you blink, which is not entirely surprising when you consider how much development occurs between the ages of 2 and 5. Still, the changes should occur on a relatively gradual curve, not from one day to the next. Think how surprised you’d be if your 2 year old suddenly started to speak in compound sentences instead of single words or suddenly started riding a two-wheeled bike. Drastic behavior changes can mean a serious problem.


Children who are around the age of 2 have little or no impulse control. If Johnny swipes Suzie’s blocks, Suzie may very well clobber him to get them back. But sudden and seriously aggressive behavior is something else again. If your child is attacking you or other adults, constantly fighting with his playmates -- especially if he bites or hits hard enough to leave bruises -- it could be conduct disorder, a serious behavior problem. Repeated aggressive outbursts like these should be reported to his pediatrician.


Stress affects children in many of the same ways it affects adults, but toddlers can’t always tell you just what’s bugging them. Instead, they may revert to an earlier stage of development, such as thumb-sucking or wetting their pants when they’ve been potty trained for over a year. A stressed toddler may be excessively defiant, develop sleep problems or start to have nightmares. Nightmares are actually not unusual in toddlers, but repeated nightmares in children who awaken sobbing inconsolably and start to avoid sleep may be a sign of stress.

Sexual Abuse

It’s a thoroughly unpleasant subject, but children who have been sexually abused may change overnight. Your outgoing, never-met-a-stranger 4 year old suddenly tries to hide behind you or runs shrieking when the babysitter or Uncle Lou walks in the door. This is a case where it’s vitally important to trust your instincts. A toddler whose behavior suddenly changes, especially if it consists of avoiding certain people or places, doesn’t have the words to explain what happened. She just knows it was bad and she’s trying to stay away from the bad people.

Mental Illness

Drastic behavior changes can signal the onset of mental illness. Even toddlers get the blues, and serious depression can affect very young children. Attention deficit hyperactivity disorder, or ADHD, is another mental illness that may occur at a young age. By age 2 or 3, toddlers may develop signs of ADHD, according to MayoClinic.com. You know your toddler better than anyone else. If you see behavior that just doesn’t seem right, especially with sudden and dramatic changes, consult his pediatrician or family doctor.

About the Author

Beth Greenwood is an RN and has been a writer since 2010. She specializes in medical and health topics, as well as career articles about health care professions. Greenwood holds an Associate of Science in nursing from Shasta College.

Photo Credits

  • Jupiterimages/Photos.com/Getty Images