Amoxicillin Side Effects in Dogs

By Carole Ann

Amoxicillin is prescribed for your dog to treat bacterial infections of the urinary tract, skin, ears, respiratory system, abscesses and from wounds. It kills bacteria by suppressing its production in the cells. In some cases it may cause side effects in dogs that are similar to those for humans. Administer all medication as prescribed by your veterinarian.

Upset Stomach

Amoxicillin can cause your dog to have an upset stomach. Try giving your dog the medicine with food to prevent this.


Some dogs may having vomiting from taking amoxicillin. If giving the medication with food does not help and your dog's vomiting continues, contact your veterinarian.


A common side effect of amoxicillin is diarrhea. As with humans, amoxicillin can alter the bacteria in your dog's bowels, causing loose or runny stools. If diarrhea continues, contact your veterinarian.

Loss of Appetite

Your dog may lose her appetite because of the upset stomach. Since some side effects subside during treatment, your dog may begin to feel better after a couple of days. If your dog does not begin eating again after a day or two, contact your veterinarian.

Allergic Reaction

Some dogs have an allergic reaction to amoxicillin. Symptoms include rashes, fever, breathing difficulty, swelling of the face or legs, rapid heartbeat and loss of balance. If this occurs, seek immediate veterinary care.

Drug Interactions

Amoxicillin may cause an adverse reaction when taken in conjunction with cerythromycin, hloramphenicol, tetracycline, cephalosporins, aminoglycosides and probenecid. Be sure to inform your veterinarian of any other medications your dog is taking.