ASPCA Animal Poison Control: (888) 426-4435
Pet Poison Helpline: (855) 764-7661
Poison Control (Human): (800) 222-1222 — While primarily for humans, they also provide animal toxin information.
Please note: Animal poison control services charge a fee, but it's well worth the cost. They'll provide a case number that allows emergency veterinarians to consult directly with their toxicology experts. They also maintain an extensive database of toxic substances and can help determine whether your cat needs immediate veterinary care.