The severity of TBIs can be identified by the duration of effects.

In Mild TBI (or concussion) symptoms include:

- No or only briefly (a few seconds or minutes up to 30 minutes) loss of consciousness
- Headache, ringing in ears, blurred vision, nausea/vomiting
- Dizziness/lightheadedness, impaired balance/coordination
- Confusion/disorientation and/or memory loss (<24 hours)

In Moderate TBI symptoms are similar to mild TBI but include:

- Confusion or disorientation (>24 hours)
- Loss of consciousness (> 30 minutes but < 24 hours)
- Memory loss (>24 hours but < 7 days)

In Severe TBI symptoms are similar to mild TBI but include:

- Confusion or disorientation (>24 hours)
- Loss of consciousness (> 24 hours)
- Memory loss (>7 days)