Nasal Discharge in Cats: What the Color Means

Nasal discharge in cats is very commonly connected to upper respiratory infections, a category that includes several viruses (feline herpesvirus and calicivirus being the most common) that spread easily in multi-cat environments like shelters, and that many cats carry in a dormant form that can flare up during times of stress.

Clear discharge often accompanies the early stage of an infection or mild irritation. Thick yellow or green discharge suggests either a more advanced viral infection or a secondary bacterial infection layered on top. One-sided discharge, similar to dogs, raises the possibility of a foreign object, a dental issue affecting the nasal passage, or in older cats, a mass or polyp — this pattern is worth specifically investigating rather than assuming it's simply an upper respiratory infection.

Because nasal discharge affects a cat's sense of smell, and smell drives much of a cat's interest in eating, congestion and discharge often come paired with reduced appetite — a combination that needs attention specifically because of how quickly cats can decline when they stop eating.

What to do: Mild clear discharge in an otherwise well-eating cat can often be monitored for a few days, especially if a stressful event might have triggered a mild flare. Thick colored discharge, discharge from one side only, or any reduction in eating alongside the congestion warrants a vet visit — appetite loss specifically needs fast attention given cats' unique metabolic risks, regardless of the nasal symptom's own severity.

If reduced appetite is becoming the bigger concern, here's more on why smell-related appetite loss in congested cats needs quick attention.