General Psychiatry

Warning Signs of Mental Illness

Trying to tell the difference between what expected behaviors are and what might be the signs of a mental illness isn't always easy. There's no easy test that can let someone know if there is mental illness or if actions and thoughts might be typical behaviors of a person or the result of an illness.



Each illness has its own symptoms, but common signs of mental illness in adults and adolescents can include the following:

  • Sleeping Habits

    changes, either sleeping too much or too little, or feeling tired with low energy.

  • Eating Habits

    changes, such as increased hunger or lack of appetite.

  • Mood Changes

    like rapid or dramatic shifts in emotions. 

  • Sadness

    for no reason or in an excessive manner or thinking about suicide.

  • Problems Thinking or with Concentration and Memory. 
  • Withdrawal and Loss of Interest

    in activities previously enjoyed. Avoiding friends and social activities.

  • Drop in Functioning

    at school, work or social activities, such as quitting sports, decreased academic performance or difficulty performing usual tasks.

  • Multiple Physical Complaints

    without obvious causes, such as headaches, stomach aches, vague and ongoing “aches and pains”.

  • Nervousness or Excessive Worrying

    without cause or out of proportion.

  • Fear or Suspiciousness 

    of others in an illogical way.

  • Illogical Thinking

    or unusual or exaggerated beliefs about personal powers to understand meanings or influence events.

  • Unusual Behavior

    or odd, uncharacteristic, peculiar behavior.

  • Use or Overuse of Substances

    like alcohol or drugs.

One or two of these symptoms alone can’t predict a mental illness, but may indicate a need for further evaluation. If a person is experiencing several at one time and the symptoms are causing serious problems in the ability to study, work or relate to others, he/she should be seen by a psychiatrist. People with suicidal thoughts or intent, or thoughts of harming others, need immediate attention.

Mental health conditions can also begin to develop in young children, but because children are still learning how to identify and talk about thoughts and emotions, their most obvious symptoms are behavioral. Symptoms in children may include the following:

  • Changes in school performance.
  • Excessive worry or anxiety, for instance fighting to avoid bed or school.
  • Hyperactive behavior.
  • Frequent nightmares.
  • Frequent disobedience or aggression.
  • Frequent temper tantrums.

Diagnosis & Treatment


Knowing warning signs can help let you know if you need to speak to a professional. For many people, getting an accurate diagnosis is the first step in a treatment plan.

Unlike diabetes or hypertension, there is no medical test that can accurately diagnose mental illness. An interview with a psychiatrist is required to assess symptoms and make a diagnosis. If you feel you or somebody you know needs help, reach out to your local mental health hospital or clinic for more guidance.

Treatments for mental illness vary by diagnosis and by person. There’s no “one size fits all” treatment. Treatment options can include medications, psychotherapy or a combination of both.