Yes, it’s not just the smoke—even if you’ve eaten something with cannabis, your eyes can get red because of how THC affects your body. It dilates the capillaries in your eye, causing them to fill with blood, giving you a red tint. This usually lasts anywhere from 30 minutes to a few hours, depending on the dose and your body. And quick relief can come from eye drops, moisture, a cold compress, or some vitamins—just for basic comfort.