Parsley contains dangerous compounds that can cause photosensitization.
When too much of this herb is consumed by your cat, it may result in sunburn, blisters, and sores.
Suggestions
If you choose to give your cat parsley, it should only be in very small amounts and infrequently.
Monitor for any signs of adverse reactions such as sunburn, blisters, or sores and consult your veterinarian if any symptoms appear.
Note: even if labeled as safe, any food can potentially cause allergies. When introducing a new food, please feed a small amount and observe your cat for any allergic reactions.