Benadryl, or diphenhydramine hydrochloride, when taken by mouth, works within 15 to 60 minutes. When injected through a muscle, it takes 20 to 30 minutes to work. When injected through a vein, it...
The time a cat can take antibiotics, depends on what it is for. If your cat has really bad cat flu it could be on it for over 7 days. A mild dose of cat flu will have a cat on antibiotics for a week...
If ingested, the medication takes about 20 to 40 minutes to take effect. The time it takes is also effected by the acid content in the stomach, which can adjusted via food intake.