Signs and Symptoms of Critical Incident Stress

After a critical incident, you may experience one or more of the following reactions:

​Physical reactions

  1. Feeling very tired
  2. Nausea/vomiting
  3. Weakness
  4. Trouble breathing
  5. Chest pain
  6. Rapid heartbeat
  7. Headaches
  8. Dry mouth or constant thirst
  9. High blood pressure
  10. Dizziness or fainting
  11. Worsening allergies
  12. Signs of shock

Thinking (cognitive) reactions

  1. Blaming yourself or others
  2. Confusion
  3. Shorter attention span
  4. Flashbacks
  5. Trouble concentrating or loss of confidence
  6. Negative self-talk
  7. Reduced awareness
  8. Disturbing thoughts
  9. Nightmares
  10. Being easily distracted
  11. Short-term memory problems
  12. Feeling disoriented about time, place or people

Emotional reactions

  1. Frustration
  2. A strong need for others to understand what you experienced
  3. Anxiety
  4. Guilt or strong feelings for those involved
  5. Sense of loss
  6. Anger
  7. Denial
  8. Fear of losing control
  9. Irritability or agitation
  10. Depression
  11. Feeling overwhelmed
  12. Feeling isolated
  13. Difficulty controlling emotions

Behavioural reactions

  1. Emotional outbursts
  2. Changes in activity level
  3. Trouble sleeping
  4. Smoking more than usual
  5. Being easily startled or constantly on alert
  6. Antisocial behaviour
  7. Withdrawing from others
  8. Changes in eating habits (eating more or less)
  9. Difficulty relaxing
  10. Restlessness or fidgeting
  11. Increased use of alcohol or other substances
  12. Changes in sex drive
Source: Critical Incident Stress Management (CISM) Program, Canada Border Services Agency - Pacific Region: CISM Mass Event Response Plan (2026).