pet medications purchased online or from a "people" pharmacy may not be as safe as you think

Are you considering purchasing your pet medications from an Internet or mail-order company, or having your pet’s prescriptions filled at a retail pharmacy? Before you purchase pet medications from a source other than your veterinarian, you may want to consider these issues.

Remember that your vet knows your pet and can best determine appropriate medications

Knowledge of Appropriate Medications for Pets

Your veterinarian has received extensive training in animal medications and is best qualified to prescribe the appropriate form of medication and at the appropriate dosage. Not all medications are safe for pets. For instance, Tylenol (in any form) should never be given to pets, as it can prove fatal. Similarly, some types of insulin are not appropriate for certain diabetic pets. If a pharmacist suggests a substitution in medication from what is prescribed by your veterinarian, you should confirm this substitution with your veterinarian before administering the medication to your pet.


Even though human medication can be used in pets, often the dosage Pet medication dosages do NOT correspond to human necessarily different. Human pharmacists are trained in human pharmacology, not veterinary pharmacology, so they may not be aware of these important differences. An example of this is thyroid medication. Dogs require a much higher dose than would be appropriate in humans. Human pharmacists who are not aware of this may try to lower the prescribed amount. This change would result in an unfavorable response to treatment by the pet. If a pharmacist suggests any change in dosage or frequency of administration of a medication, be sure to confirm this change with your veterinarian before administering the medication to your pet.

Care of Medications

To preserve their effectiveness, certain medications must be kept in a controlled environment. You can be assured that medications obtained from your veterinarian have been shipped and stored properly. In most cases, the veterinary drug manufacturer will stand behind its medication should an adverse event occur, something that may not be guaranteed if the medication is purchased from a source other than your veterinarian.


Medication should not be given to your pet until it is determined to be safe – and necessary. For example, dogs with an active heartworm infection should not be given preventive heartworm medication as it can lead to a fatal reaction. Screening for the infection prior to starting the preventive is a necessity. Retail (human) pharmacies are not equipped to do this screening.
Medication for cats is different than medication for dogs.

Cats and Dogs Are Different

And so are their medications. Medications specifically designed for cats or dogs are not interchangeable. For instance, canine flea medications can be fatal if given to cats. Your veterinarian will ensure that the medications you receive from them are species-appropriate.

Your vet is ready to monitor and adjust pet medication as needed.


Certain medications require monitoring and follow-up care, dosage adjustments, or continued lab tests or examinations. For that reason, and due to the unfortunate possibility of an adverse reaction, it is important to have a relationship established with your veterinarian, so that appropriate and timely care can be given.