I was hoping to hear back from you with some additional information, but I will send my answer now, and then, if you have any further questions, please click 'reply.'
Because the liquid catnip spray was the only 'new' thing introduced before they both started feeling ill, I would assume that they ingested some of the spray and it's not agreeing with them. Here is more information about cats and catnip:
If their pupils are dilated or don't react to light (become smaller in bright light and larger in dim light) and/or their gums are pale, this could indicate a toxic, allergic or neurological reaction to an ingredient or ingredients in the liquid catnip spray. If they're showing any gastrointestinal symptoms, like vomiting or diarrhea or blood in the stool, they may have ingested a different substance that was toxic or is causing an intestinal obstruction.
Their food may have been tainted and that is causing them to feel ill.
You have to examine everything that they were exposed to or might have inhaled/ingested since last night when they played with the catnip spray, since both cats seem to be affected.
If their symptoms do not improve, remain the same or worsen, they will need to be seen by a vet in person, as soon as possible. Since we're going into a weekend, you may need to bring them to an ER vet center if your regular vet doesn't have weekend or emergency hours.
I hope all will be well with your two furkids!
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