Blood shot eyes

Two very obvious reasons for blood shot eyes are excessive drinking or smoking, but if neither of these are contributing to the problem then other reasons can be:
allergies to airborne irritants (although the eyes are usually itchy and watery as well in this case),
– eyestrain and/or fatigue.
– Sometimes an inability to digest protein efficiently over a long period, can lead to amino-acid deficiencies.  These in turn have been known to contribute to reddened eyes.
– Another, not uncommon reason is a deficiency of vitamin B2 (riboflavin). If
this is the cause then a simple supplement of Vitamin B2 taken daily in conjunction with a vitamin B complex tablet will correct the problem.
See also page on ‘Cracks at the Corner of the Mouth’.

Irritation from airborne irritants can be alleviated, but obviously not
eliminated, by the use of Quercetin, which will reduce histamine reaction to allergies and also reduce inflammation. I have seen very good improvement to eye inflammatory conditions with the use a well tolerated product that contains 500mg of Quercetin plus other bioflavonoids.

Evening primrose oil can also help reduce redness.
Go to on-line shop for Quercetin or Evening primrose oil

Eyestrain can be eased by making sure to look away into the distance
regularly (as in every 10-15minutes) whenever doing close work. However, it is a
good idea if strain continues to pay a visit to a good Optician!

If fatigue is possibly a cause then you must take steps to alleviate it!
Get some good quality rest and extra quality sleep.