10 Mental Health Illnesses: Symptoms and Treatment Options
Mental health illnesses can affect thoughts, emotions, behaviour, perception, relationships and daily functioning. They are health conditions—not signs of weakness, poor character or insufficient willpower.
Common examples include depression, anxiety disorders, bipolar disorder, schizophrenia, obsessive-compulsive disorder, post-traumatic stress disorder, eating disorders, attention-deficit/hyperactivity disorder, borderline personality disorder and substance use disorders.
Healthcare organizations often use the terms mental disorders and mental health conditions. Symptoms frequently overlap, and the same symptom can have several possible causes. A qualified professional considers duration, severity, functional impact, physical health, medicines, substance use, personal history and immediate safety before making a diagnosis.
Get urgent help now when safety is at risk
Call your local emergency number or go to the nearest emergency department if someone has suicidal intent, a suicide plan, an intention to harm another person, an overdose, life-threatening withdrawal, dangerous psychosis, mania with unsafe behaviour, severe confusion or an inability to maintain immediate safety.
United States: Call 911 for immediate danger or call/text 988 for the Suicide & Crisis Lifeline. Outside the United States, contact the local emergency number or national crisis service.
Quick answer: What are common mental health illnesses?
Common mental health illnesses include depression, anxiety disorders, bipolar disorder, schizophrenia, OCD, PTSD, eating disorders, ADHD, borderline personality disorder and substance use disorders. Treatment may involve condition-specific psychotherapy, medication, medical monitoring, rehabilitation, family or school support, recovery services or coordinated care.
According to the World Health Organization, about 1.1 billion people worldwide were living with a mental disorder in 2021, with anxiety and depressive disorders among the most common. Effective treatments exist, although access to care remains uneven.
This guide provides an educational overview. It cannot determine whether you or another person has a mental-health condition or recommend an individual treatment plan.
What Are Mental Health Illnesses?
Mental health illnesses are clinically significant conditions that can disturb thinking, emotional regulation, behaviour or perception and cause distress, functional impairment or safety risks.
They can affect:
- Emotions and mood.
- Thoughts and beliefs.
- Attention and memory.
- Sleep and appetite.
- Energy and motivation.
- Impulse control.
- Relationships.
- Work or school performance.
- Personal care.
- Safety.
Mental Health Is Not the Same as Mental Illness
Mental health describes emotional, psychological and social well-being. Everyone has mental health, just as everyone has physical health.
A mental health disorder involves a pattern of symptoms that causes clinically significant distress, impairment or risk. Someone can experience stress or emotional difficulty without meeting the criteria for a disorder.
Explore the wider relationship in our guide to mental health versus physical health.
Why Self-Diagnosis Is Unreliable
Symptoms such as fatigue, poor concentration, insomnia, appetite changes and irritability may appear in several mental-health conditions. They may also be caused or worsened by:
- Thyroid disease.
- Anaemia.
- Neurological conditions.
- Infection.
- Sleep disorders.
- Medication effects.
- Alcohol or drug use.
- Grief or major stress.
A diagnosis should therefore come from a qualified professional who can evaluate the full clinical picture.
General Warning Signs of a Possible Mental Health Condition
One symptom does not establish a diagnosis. Professional assessment becomes more important when changes persist, recur, worsen or interfere with daily life.
- Persistent sadness, anxiety, irritability or emotional numbness.
- Marked loss of interest or motivation.
- Major changes in sleep or appetite.
- Extreme mood or energy changes.
- Difficulty concentrating or making decisions.
- Withdrawal from friends, family, school or work.
- Unusual beliefs or perceptions.
- Repeated rituals or behaviours that feel impossible to resist.
- Dangerous impulsive behaviour.
- Severe food restriction, bingeing or purging.
- Escalating alcohol or drug use.
- Neglect of personal care.
- Thoughts of death, self-harm or harming another person.
10 Mental Health Illnesses and Their Treatment: Comparison Table
| Condition | Possible core signs | Common treatment categories |
|---|---|---|
| Depression | Low mood, loss of interest, hopelessness and impaired functioning | Psychotherapy, medication and selected brain-stimulation therapies |
| Anxiety disorders | Excessive fear, worry, panic or avoidance | CBT, exposure therapy and medication |
| Bipolar disorder | Episodes of mania or hypomania and depression | Mood stabilizers, antipsychotics and psychotherapy |
| Schizophrenia | Psychosis, disorganization, reduced motivation and cognitive symptoms | Antipsychotics, coordinated care and rehabilitation |
| OCD | Obsessions and compulsions | Exposure and response prevention, CBT and SSRIs |
| PTSD | Intrusions, avoidance, negative mood and hyperarousal | Trauma-focused psychotherapy and medication |
| Eating disorders | Restriction, bingeing, purging or body-image distress | Medical, nutritional and psychological care |
| ADHD | Persistent inattention, hyperactivity or impulsivity | Medication, behavioural care and school or workplace support |
| Borderline personality disorder | Emotional, relationship and self-image instability | Structured psychotherapy, particularly DBT |
| Substance use disorders | Loss of control and continued use despite harm | Medication when available, behavioural therapy and recovery support |
Important: These are broad summaries—not personalized treatment plans. Care differs by age, severity, medical history, pregnancy status, co-occurring conditions, medicines, access and individual preference.
1. Depression
What Is Depression?
Depression is a mood disorder involving persistent low mood or loss of interest or pleasure, together with symptoms that impair daily functioning.
Possible Symptoms
- Sadness, emptiness or irritability.
- Loss of interest or pleasure.
- Hopelessness, guilt or worthlessness.
- Sleep changes.
- Appetite or weight changes.
- Fatigue.
- Difficulty concentrating.
- Physical slowing or agitation.
- Thoughts of death or suicide.
Depression Treatment May Include
- Psychotherapy.
- Antidepressant medication.
- Combined psychotherapy and medication.
- Treatment of contributing physical conditions.
- Electroconvulsive therapy or another brain-stimulation treatment in selected severe or treatment-resistant cases.
Treatment choice depends on symptom severity, previous response, bipolar-disorder screening, medical history and individual preference.
Safety note: Suicide risk, psychotic depression, severe self-neglect or inability to remain safe requires urgent professional assessment.
Related reading:
2. Anxiety Disorders
What Are Anxiety Disorders?
Anxiety disorders involve excessive fear, worry, panic or avoidance that causes significant distress or interferes with life.
Examples include generalized anxiety disorder, panic disorder, social anxiety disorder, specific phobias and separation anxiety disorder.
Possible Symptoms
- Persistent or difficult-to-control worry.
- Panic attacks.
- Restlessness or feeling on edge.
- Irritability.
- Muscle tension.
- Poor concentration.
- Avoidance.
- Nausea, sweating, trembling or palpitations.
- Sleep difficulty.
Anxiety Treatment May Include
- Cognitive behavioural therapy.
- Exposure-based therapy.
- Antidepressants such as SSRIs or SNRIs.
- Other medicines selected for the specific disorder.
- Relaxation and stress-management skills as supportive care.
Benzodiazepines may be used in limited circumstances but are generally unsuitable as routine long-term treatment because of sedation, tolerance and dependence risks.
Related reading: Can Anxiety Cause Nausea?
3. Bipolar Disorder
What Is Bipolar Disorder?
Bipolar disorder involves episodes of depression and episodes of mania or hypomania. It is not the same as ordinary moodiness or emotional changes within one difficult day.
Possible Manic Symptoms
- Unusually elevated or irritable mood.
- Markedly increased energy or activity.
- Reduced need for sleep.
- Rapid speech.
- Racing thoughts.
- Inflated confidence or grandiosity.
- Impulsive or risky behaviour.
- Psychosis in some severe episodes.
Bipolar Disorder Treatment May Include
- Mood-stabilizing medication.
- Antipsychotic medication.
- Psychotherapy.
- Psychoeducation.
- Relapse-prevention planning.
- Regular sleep and daily routines as supportive measures.
- Family support.
Medication is usually central to treatment. Antidepressants should not be presented as stand-alone therapy because they may trigger or worsen mania in susceptible people.
Emergency warning: Mania involving psychosis, dangerous spending, reckless driving, aggression, severe sleep loss or inability to maintain safety may require emergency or hospital care.
4. Schizophrenia
What Is Schizophrenia?
Schizophrenia is a serious mental disorder that may affect perception, thought, speech, motivation, emotional expression and daily functioning.
Possible Symptoms
- Hallucinations involving sound, vision, touch, smell or taste.
- Delusions.
- Disorganized speech.
- Disorganized or unusual behaviour.
- Reduced emotional expression.
- Low motivation.
- Social withdrawal.
- Cognitive difficulties.
Schizophrenia Treatment May Include
- Antipsychotic medication.
- Individual psychotherapy.
- Coordinated specialty care after first-episode psychosis.
- Family education and support.
- Supported employment or education.
- Rehabilitation and daily-living support.
- Treatment of substance use and other co-occurring conditions.
Coordinated specialty care is a team-based, recovery-focused approach for early psychosis that may combine medication, psychotherapy, family education, case management and work or education support.
People with schizophrenia are not automatically dangerous. Stigma can prevent people from seeking care and participating fully in family and community life.
5. Obsessive-Compulsive Disorder
What Is OCD?
Obsessive-compulsive disorder involves recurring, unwanted thoughts, urges or images called obsessions and repetitive behaviours or mental acts called compulsions.
Possible Symptoms
- Contamination fears.
- Repeated checking.
- Intrusive harm-related thoughts.
- A need for symmetry or exactness.
- Repetitive washing.
- Mental counting or reviewing.
- Reassurance seeking.
- Rituals that consume substantial time.
Unwanted intrusive thoughts do not automatically indicate intent. A professional should assess distressing thoughts when there is uncertainty about safety.
OCD Treatment May Include
- Exposure and response prevention.
- Cognitive behavioural therapy.
- SSRI medication.
- Combined psychotherapy and medication.
- Selected brain-stimulation approaches for severe treatment-resistant cases.
Exposure and response prevention is a specific form of CBT in which a person gradually faces triggers while learning not to perform the usual compulsion.
6. Post-Traumatic Stress Disorder
What Is PTSD?
Post-traumatic stress disorder may develop after experiencing or witnessing trauma. Not everyone exposed to trauma develops PTSD.
Main Symptom Groups
- Intrusive memories, nightmares or flashbacks.
- Avoidance of trauma reminders.
- Negative changes in mood, beliefs or emotional connection.
- Hypervigilance, irritability or exaggerated startle.
- Sleep and concentration problems.
PTSD Treatment May Include
- Trauma-focused psychotherapy.
- Cognitive processing therapy.
- Prolonged exposure.
- Eye movement desensitization and reprocessing.
- Medication.
- Treatment for depression, substance use or other co-occurring conditions.
Trauma treatment should be delivered by a qualified professional with appropriate training. General relaxation advice alone is not equivalent to trauma-focused treatment.
7. Eating Disorders
What Are Eating Disorders?
Eating disorders are serious mental and physical illnesses involving persistent disturbances in eating behaviour and related thoughts or emotions.
Examples include anorexia nervosa, bulimia nervosa, binge-eating disorder, avoidant/restrictive food intake disorder and other specified feeding or eating disorders.
Possible Warning Signs
- Severe food restriction.
- Binge eating.
- Vomiting or laxative misuse.
- Compulsive exercise.
- Intense fear of weight gain.
- Rapid or significant weight change.
- Dizziness or fainting.
- Preoccupation with food, weight or body shape.
A dangerous eating disorder can occur at any body size.
Eating Disorder Treatment May Include
- Medical monitoring.
- Nutritional rehabilitation and counselling.
- Individual, group or family psychotherapy.
- Family-based treatment for selected children and adolescents.
- Medication for selected disorders or co-occurring conditions.
- Hospital or residential treatment when medically necessary.
Urgent medical warning: Fainting, chest pain, severe weakness, dehydration, vomiting blood, confusion or other signs of medical instability require immediate medical care.
8. Attention-Deficit/Hyperactivity Disorder
What Is ADHD?
Attention-deficit/hyperactivity disorder is a neurodevelopmental disorder involving persistent patterns of inattention, hyperactivity, impulsivity or a combination that interferes with functioning.
Possible Symptoms
- Difficulty sustaining attention.
- Disorganization.
- Forgetfulness.
- Losing necessary items.
- Restlessness.
- Excessive talking.
- Interrupting.
- Difficulty waiting.
- Acting without considering consequences.
Symptoms are assessed in relation to age, development, the settings in which they occur and the degree of impairment. Sleep loss, anxiety, depression, trauma and learning difficulties can resemble or worsen ADHD symptoms.
ADHD Treatment May Include
- Stimulant medication.
- Non-stimulant medication.
- Behavioural interventions.
- Cognitive behavioural therapy for some adults.
- Parent education.
- School-based support.
- Workplace accommodations.
- Organizational-skills training.
9. Borderline Personality Disorder
What Is Borderline Personality Disorder?
Borderline personality disorder can involve persistent instability in emotions, relationships, self-image and behaviour.
Possible Symptoms
- Intense emotional changes.
- Fear of abandonment.
- Unstable relationships.
- Impulsive behaviour.
- Chronic feelings of emptiness.
- Intense anger.
- Self-harm or suicidal behaviour.
- Temporary paranoia or dissociation during stress.
BPD Treatment May Include
- Dialectical behaviour therapy.
- Mentalization-based treatment.
- Other structured psychotherapies.
- Safety planning.
- Treatment of co-occurring depression, PTSD, eating disorders or substance use.
Psychotherapy is the primary treatment. Medication may be prescribed for particular symptoms or co-occurring conditions, but no medication should be presented as a cure for the core disorder.
10. Substance Use Disorders
What Are Substance Use Disorders?
Substance use disorders involve a problematic pattern of alcohol or drug use that causes significant impairment, health risks or distress.
Use person-first language such as “a person with a substance use disorder,” rather than stigmatizing labels.
Possible Symptoms
- Difficulty controlling use.
- Strong cravings.
- Continued use despite harm.
- Tolerance.
- Withdrawal.
- Neglecting responsibilities.
- Risky use.
- Repeated unsuccessful attempts to stop.
Substance Use Disorder Treatment May Include
- Medical assessment.
- Withdrawal management when necessary.
- Behavioural therapies.
- Medication for opioid, alcohol or tobacco use disorders.
- Overdose-prevention services.
- Peer and recovery support.
- Treatment of co-occurring mental-health conditions.
- Residential or outpatient care based on need.
Withdrawal management alone is not complete addiction treatment. Ongoing treatment and recovery support reduce relapse and health risks.
Safety note: Alcohol and sedative withdrawal can be life-threatening. A person with physical dependence should not attempt abrupt withdrawal without medical guidance.
How Are Mental Health Illnesses Diagnosed?
Diagnosis is based on a clinical assessment rather than one symptom, blood test or online questionnaire.
A Professional May Review
- Current symptoms.
- How long symptoms have lasted.
- Functional impact.
- Personal and family mental-health history.
- Physical health and neurological symptoms.
- Sleep and appetite.
- Medicines and supplements.
- Alcohol or drug use.
- Trauma history.
- Developmental and school history when relevant.
- Immediate safety.
Screening Tools
Questionnaires may help identify symptoms that require further assessment, but a screening score is not a diagnosis by itself.
Medical Tests
Blood tests, physical examination or other investigations may be used to identify conditions that could cause or worsen psychiatric symptoms.
Can Someone Have More Than One Condition?
Yes. Depression, anxiety, PTSD, eating disorders, ADHD, substance use and other conditions may occur together. Treatment should address the full clinical picture rather than focusing on one label in isolation.
How to Find Help for a Mental Health Condition
Possible starting points include a primary-care clinician, psychiatrist, psychologist, licensed therapist, community mental-health clinic, school or university service, eating-disorder service or addiction-treatment service.
What Is the Difference Between a Psychiatrist and a Psychologist?
A psychiatrist is a medical doctor who can diagnose mental-health conditions, prescribe medicine and evaluate physical or medication-related factors.
A psychologist is trained in psychological assessment and psychotherapy. Prescribing authority varies by jurisdiction.
What to Say When Requesting Help
“I have been experiencing changes in my mood, thoughts, sleep and daily functioning. They are not improving, and I would like a mental-health assessment.”
When safety is at risk, use direct language:
“I am having thoughts of harming myself or someone else, and I do not feel safe. I need emergency help now.”
Can Lifestyle Changes Help Mental Health?
Sleep, physical activity, regular meals, daily structure, social connection and reducing harmful substance use may support mental well-being and recovery.
They do not replace condition-specific professional treatment.
Related guides:
How Can Mental Health Illnesses Affect Work?
Mental-health conditions can affect concentration, memory, energy, attendance, communication, confidence and decision-making. A person may also be present at work but unable to function at their usual level.
Supportive measures may include access to mental-health care, reasonable workplace accommodations, flexible scheduling when appropriate, protected medical leave, clear workloads and expectations, confidential employee-assistance services and anti-stigma policies.
Employment difficulties should not be interpreted as laziness or a lack of commitment. Appropriate treatment and workplace support can improve functioning.
Mental Health Illnesses: Key Takeaways
- Mental health illnesses are health conditions—not personal failures.
- Symptoms overlap and cannot reliably be diagnosed from an online list.
- Depression and anxiety disorders are common but require individualized care.
- Bipolar disorder and schizophrenia may require long-term medication and coordinated support.
- Exposure and response prevention is a leading psychotherapy for OCD.
- PTSD treatment commonly uses trauma-focused psychotherapy.
- Eating disorders can be medically dangerous at any body size.
- ADHD is a neurodevelopmental condition, not simply poor motivation.
- Psychotherapy is the primary treatment for borderline personality disorder.
- Substance withdrawal management alone is not complete treatment.
- Suicidal intent, dangerous psychosis, mania or severe medical instability requires emergency help.
My Editorial Approach to Mental Health Content
Adel Galal’s editorial perspective
Mental-health content should explain symptoms and treatment without encouraging self-diagnosis or reinforcing stigma. My role is not to diagnose readers or prescribe care. It is to compare authoritative sources, remove exaggerated claims and help readers understand when professional or emergency support is needed.
For this guide, I prioritized current information from the National Institute of Mental Health, the World Health Organization, the Substance Abuse and Mental Health Services Administration and the 988 Suicide & Crisis Lifeline.
Frequently Asked Questions About Mental Health Illnesses
What are 10 common mental health illnesses?
This guide covers depression, anxiety disorders, bipolar disorder, schizophrenia, OCD, PTSD, eating disorders, ADHD, borderline personality disorder and substance use disorders.
What is the difference between mental health and mental illness?
Mental health refers broadly to emotional, psychological and social well-being. A mental disorder involves clinically significant symptoms, distress, impairment or safety risk.
How are mental health illnesses treated?
Treatment may include psychotherapy, medication, medical monitoring, rehabilitation, family support, school or workplace accommodations and substance-use services. The correct plan depends on the diagnosis and individual.
Can mental health illnesses be cured?
Outcomes vary. Some people experience full recovery, while others manage recurring or long-term symptoms successfully with continuing treatment and support.
How do I know whether I need professional help?
Seek an assessment when symptoms persist, worsen, cause distress, interfere with daily life or create concern about safety.
Can someone have more than one mental-health condition?
Yes. Mental-health conditions frequently occur together, and treatment should consider all relevant symptoms and diagnoses.
Is medication always necessary?
No. Medicine needs depend on the condition, severity, age, medical history and individual preference. Medication is central for some disorders, while psychotherapy may be the primary treatment for others.
Can lifestyle changes treat mental illness?
Sleep, movement, nutrition, structure and social connection may support health and recovery, but they do not replace condition-specific professional care.
Are people with schizophrenia dangerous?
A diagnosis of schizophrenia does not mean someone is dangerous. Risk depends on individual circumstances, symptoms, substance use, treatment access and other factors. Stigmatizing assumptions can prevent people from seeking help.
Can children and teenagers have mental health disorders?
Yes. Anxiety, depression, ADHD, eating disorders, trauma-related conditions and other disorders can begin during childhood or adolescence. Assessment should account for age and development.
When is a mental-health problem an emergency?
It is an emergency when there is suicidal intent, an intention to harm another person, dangerous psychosis, mania with unsafe behaviour, overdose, severe withdrawal or inability to maintain immediate safety.
Where can I find crisis help in the United States?
Call 911 for immediate life-threatening danger. Call or text 988 for free, confidential crisis support.
Sources and Medical References
- World Health Organization — Mental disorders
- National Institute of Mental Health — Mental-health topics
- NIMH — Psychotherapies
- NIMH — Depression
- WHO — Anxiety disorders
- NIMH — Bipolar disorder
- NIMH — Schizophrenia
- NIMH — Obsessive-compulsive disorder
- NIMH — Post-traumatic stress disorder
- NIMH — Eating disorders
- NIMH — Attention-deficit/hyperactivity disorder
- NIMH — Borderline personality disorder
- SAMHSA — Substance use disorder treatment options
- 988 Suicide & Crisis Lifeline
Part of the NextFitLife Mental Health Series
Continue with our guides to high-functioning depression symptoms, physical symptoms of anxiety, postpartum depression symptoms, mental and physical health, the NextFitLife Health Hub and Health Articles.
Medical and crisis disclaimer
This article provides general education and cannot diagnose a mental-health condition, assess individual safety or recommend personalized treatment. Call your local emergency number for suicidal intent, an intention to harm another person, overdose, dangerous psychosis, mania, severe confusion or inability to remain safe. In the United States, call 911 for immediate danger or call/text 988 for crisis support.
Written and source-checked by Adel Galal
Founder and Lead Writer, NextFitLife | 30+ Years of Personal Study in Health, Fitness, Nutrition, Sleep and Healthy Aging
Adel Galal creates plain-language health content by comparing authoritative medical and public-health sources, removing stigmatizing or exaggerated claims and explaining when professional or emergency support is needed.
He is not a psychiatrist, psychologist, psychotherapist, physician, addiction specialist or licensed mental-health professional. This article was editorially source-checked against NIMH, WHO, SAMHSA and 988 Lifeline resources but has not been clinically reviewed unless a named reviewer is displayed on the published page. Read the NextFitLife Medical Review Policy.
Health & wellness writer with 30+ years of experience in nutrition, fitness, and healthy aging. Founder of NextFitLife.com — evidence-based health guidance.
