For comparison just one tablespoon is thirty milliliters so a little bit goes a long way. You should however always consult a vet before administering medicine to your cat. Speak to your vet if youre in any doubt.
A liquid suspension of Benadryl should be twelve and a half milligrams per five milliliters. Typically cats take 1 mg of Benadryl for each pound of body weight two to three times a day. A higher body weight 125 to a 15-pound cat may need more. An average 10-pound cat needs 2 to 4 mg.