Sedate a cat at home using the correct dosage of Benadryl, the brand name for diphenhydramine. The correct dosage for cats is 0.5 mg to 2 mg by mouth per pound of body weight. If Benadryl doesn't work, visit your veterinarian for a prescription sedative and administer it as prescribed.
Obtain Benadryl from the store
Purchase Benadryl or generic diphenhydramine from the store. Oral tablets work best. If you can't pill your cat, purchase liquid Benadryl.
Administer the drug before you need it
Give your cat Benadryl by mouth before it's necessary to sedate your cat. Start with the smallest dosage of 0.5 mg per pound up to every eight hours. This lets you know if Benadryl will effectively sedate your cat. Diphenydramine doesn't work as a sedative on all felines.
Up the dosage
Give your cat a larger dosage of Benadryl, up to 2 mg per pound of body weight, if the lowest dose doesn't sedate your cat.
Sedate your cat with the correct dosage
Administer Benadryl in the dosage that works for your cat two hours before you need your cat to be sedate. For example, if you are traveling by car, administer Benadryl two hours prior to leaving.
Obtain a prescription
If Benadryl doesn't sedate your cat, visit your veterinarian for a sedative. Vets prescribe various drugs, including acepromazine and prozac, to sedate cats. Use the drug as directed by your veterinarian.