Most bloodshot eyes are not serious and nothing to worry about.
Bloodshot eyes can be caused by not getting enough sleep, exposure to smoke, allergies, wearing contact lenses, rubbing your eyes, inflammation of the eyes, drinking too much alcohol, staring at a computer screen too long and other eye irritants.
Sometimes bloodshot eyes may be caused by some eye disease or other medical condition or too much blood pressure.
But most times bloodshot eyes are nothing serious.
I will get bloodshot eyes when I don't get enough sleep and when I do get enough sleep the bloodshot eyes go away.
If the bloodshot eyes last longer than a week or they come back too often then you should see an eye doctor about it.