Cats can safely eat catnip. When eaten, catnip generally produces a calming, sedative effect on cats, which contrasts with the stimulant and playful reaction they might show when they just smell it. However, not all cats respond to catnip because sensitivity is genetic, and about 30-50% of cats do not react to it at all. While eating catnip is safe, consuming large amounts might cause mild gastrointestinal upset such as nausea or diarrhea. Also, some cats, like pregnant or nursing ones, cats with neurological problems, or young kittens under one year, should avoid catnip. Overall, catnip is non-toxic and can be a fun and enriching treat that cats typically enjoy in moderation.