What are allergic shinners ? please justify?

Nasal congestion: Blood from the face drains back to the heart through veins that run through the nose. If your nose is congested, the swelling puts pressure on the veins, causing the blood to back up. The skin under the eyes is so thin that you can actually see that - so it looks like a bruise under the eyes. Reducing the swelling by using nasal steroids or decongestants relieves the pressure so the blood drains.

Dark eyes: When you have allergies, the capillaries below your eye dilate. The pooling of blood in these areas give a dark hue to the skin below your eyes. It can occur with allergies but is nonspecific and can occur at other times as well. For example, you may notice dark circles below your eyes if you don't get a good night sleep. If you see this you may think about allergies but it is not a guaruntee.