Rheum

Mucus naturally discharged from eyes, nose, or mouth during sleep

Rheum is a thin mucus naturally discharged from the eyes, nose, or mouth, often during sleep. Rheum dries and gathers as a crust in the corners of the eyes or the mouth, on the eyelids, or under the nose. It is formed by a combination of mucus, nasal mucus, blood cells, skin cells, or dust.

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