Before you faint due to vasovagal syncope, you may experience some of the following: 
Pale skin
Lightheadedness
Tunnel vision — your field of vision narrows so that you see only what's in front of you
Nausea
Feeling warm
A cold, clammy sweat
Blurred vision
 During a vasovagal syncope episode, bystanders may notice: 
Jerky, abnormal movements
A slow, weak pulse
Dilated pupils
 Recovery after a vasovagal episode generally begins in less than a minute. However, if you stand up too soon after fainting — within about 15 to 30 minutes — you're at risk of fainting again.