Symptoms of PTSD come under four groupings:

Intrusive thoughts

Intrusive thoughts are memories of the trauma that you can’t get out of your mind. Flashbacks are a common experience when you have PTSD; a trigger like a sound or smell takes you back to the traumatic event. More than just a memory, a flashback makes you feel as though you’re reliving the trauma in every detail. Nightmares are also common symptoms of PTSD.

Avoidance

It can be tough to talk about the trauma that led to PTSD, which means you’re likely to avoid doing so. You might also avoid people, locations, activities, or anything else that could remind you of the trauma. Social withdrawal and resorting to substance abuse are markers of avoidance.

Changes in thoughts and mood

It’s common to experience symptoms of depression, such as hopelessness, worthlessness, despair, and guilt when you have PTSD. It’s also likely that you feel anger and severe anxiety, and lose interest in activities you used to enjoy.

Changes in physical and emotional reactions

Your physical and emotional reactions and behaviors can change when you have PTSD, and it’s not uncommon for friends and family to notice changes in you. Overreacting in stressful situations and behaving as though you were in danger are common responses. PTSD can also cause sleeping problems and changes in appetite.

These symptoms can vary in severity and frequency, depending on your situation. They might start within a few weeks or months of the event, or not until years later.