When your 4.5 kg cat's gut reacts to erythritol
The first signs typically appear within 30 minutes if she's sensitive—you might hear gurgling sounds before any diarrhoea starts. Her smaller body size means the sugar alcohol affects her gut faster than it would a larger animal. The loose stools often come in waves rather than one sudden bout, as her system tries to move the erythritol through while drawing in extra water.
By the 2-hour mark, if she hasn't shown signs yet, she may only experience mild gas. Vomiting is rarer but tends to happen within the first 90 minutes when it does occur. What you're watching for isn't blood or black stools—just increased frequency and softer consistency that should taper off within a day as her gut rebalances.
Why the keto cookie makes this different
Unlike pure erythritol powder, the cookie's fat and fiber content may slow absorption slightly, spreading out the diarrhoea over several hours rather than one intense episode. The other ingredients won't protect her from the sugar alcohol's effects but might delay them by an hour or so. Watch for signs starting at the 45-minute mark instead of the typical 30 minutes.
Her 4.5 kg body is processing both the erythritol and the cookie's dense calories, which means her gut has more to handle than if she'd licked plain sweetener. The combination could lead to more pronounced gassiness alongside the diarrhoea, with audible gut sounds as everything moves through.
The next 24 hours with your cat
Once diarrhoea starts, it usually peaks within 3-4 hours before gradually improving. She may make extra trips to the litter box during this window, passing small amounts of soft stool each time. What you don't want to see is straining without passing anything—that would suggest obstruction rather than typical erythritol reaction.
Keep her hydrated by offering water in a clean bowl every hour, but don't be surprised if she drinks less than usual—cats often reduce intake when their gut is upset. Her appetite should return within 12 hours as the erythritol clears her system. If she's still refusing food at the 24-hour mark, that's when to call your vet.
When to worry about more than diarrhoea
While most cats bounce back quickly, watch for lethargy or refusal to move—these aren't normal erythritol reactions. Her gums should stay pink and moist; if they feel tacky or look pale, she's losing too much fluid. Small breeds like yours dehydrate faster than larger cats when diarrhoea continues beyond eight hours.
The erythritol itself isn't toxic to cats like xylitol is to dogs, but the dehydration risk is real. If her stools haven't started firming up by the 18-hour mark or she's vomiting more than twice, skip the waiting period and contact your vet. For now, just track her litter box trips and keep her comfortable.
The full verdict, portion guidance and serving notes are collected on the Erythritol food facts page.