Can I Give My Cat Capstar?

No
Same: knock-down only. Never use dog spot-on products on cats (permethrin, see never-list).
Source: Merck Veterinary Manual
Already ingested? Pet Poison Helpline 855-764-7661

Skip it or ask a vet first if

under 2 lb / 4 weeks old

The safe habit

Confirm any medication decision with your veterinarian, who knows your cat's health history and other medications. VetDose shows published reference data, not prescriptions.