What is amoxicillin? 

Amoxicillin (brand names: Amoxil®, Amoxi-Tabs®, Amoxi- Drop®, Bimox®, Moxatag®, Novamoxin®) is an aminopenicillin antibiotic used to treat certain bacterial infections. Most commonly it is used to treat skin, respiratory, and urinary tract infections. 

It is used off label (extra label) to treat certain bacterial infections in cats, dogs, ferrets, birds, and reptiles. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label. 

How is amoxicillin given?

• Amoxicillin is given by mouth in the form of a tablet, capsule, or liquid suspension.
• It can be given with or without food.
• If vomiting occurs when dosed on an empty stomach, give future doses with food.
• Give the medication for the entire time prescribed, unless otherwise directed.
• Measure liquid forms carefully and shake well before administering.

This medication will take effect quickly, in about 1 to 2 hours. While effects may not be noted outwardly, gradual improvements are usually noticeable after a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once. 

Are there any potential side effects? 

Common side effects include:

• Gastrointestinal effects, such as lack of appetite, vomiting, and diarrhea

Serious adverse reactions may occur. If any of the following signs develop, stop giving amoxicillin and contact your veterinarian immediately: :

• Allergic reaction, characterized by skin rash, fever, facial swelling, or difficulty breathing
• Incoordination while walking
• Prolonged lack of appetite (in cats)

Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.  This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE amoxicillin in

• Pets that are allergic to it or other penicillins, cephalosporins, or other beta-lactam antibiotics
• Rabbits, guinea pigs, chinchillas, hamsters, or other small mammals

USE WITH CAUTION in

• Pregnant or lactating pets, although use of this medication is likely safe

Do not give by mouth to pets with a blood infection, shock, or other grave illnesses, is it will likely be ineffective.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with amoxicillin:

• Bacteriostatic antimicrobials
• Methotrexate
• Probenecid

Amoxicillin may also interact with certain urine glucose tests and cause false positive results. Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any treatment.

Is any monitoring needed with this medication?

• No specific monitoring is needed while your pet is taking this medication.
• Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store amoxicillin?

• Store capsules, tablets, and powders at room temperature, between 59°F and 86°F (15°C and 30°C)
• Store in a tight container and protected from moisture.
• The liquid suspension is best stored in the refrigerator, although it is not required.
• Discard unused liquid portions after 14 days.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.