Prescriptions and pharmacies: FAQs for pet owners

Below are answers to the most common questions we receive from pet owners about veterinary prescriptions and pharmacies.

Q: Why do I need a prescription?

A: Many prescription drugs are only effective for specific problems and may be harmful to your pet if used without a veterinary examination and diagnosis. When you are given a prescription for a medication for your pet, it means that your veterinarian has made a decision that the medication is recommended or necessary to treat your pet's health problem. Having these drugs available as prescription-only medications ensures that they are used appropriately.

For example, heartworm preventatives are labeled as "prescription-only" because it's critical that your veterinarian makes sure the medication is the right one based on your pet's health status. Heartworm preventatives target infective larvae as they are migrating through the tissue prior to reaching the bloodstream and developing into adult heartworms. If your dog (or cat) already has adult heartworms, giving a preventive medication will not effectively treat the disease because the preventives don't readily kill adult heartworms. 

There are also drugs, called "over the counter" (OTC) drugs, that don't require prescriptions. Drugs can be bought OTC when the Food and Drug Administration (FDA) determines that the directions for the drug's use aren't overly complicated and are adequate for the public to follow. In some cases, such as for common headache medications for people, the OTC version is simply a weaker strength than the prescription form. You should not use any OTC drugs for your pet unless your veterinarian has recommended such use, as many OTC drugs may not be appropriate or safe for veterinary patients.

Q: My veterinarian gave me a prescription for a pain reliever for my pet. Why can't I just buy one of the over-the-counter pain relievers at my local drug store?

A: Don't do it! Although these products are approved for use in people, many of them are not safe for pets. For example, acetaminophen (Tylenol® is the most common example) can cause severe illness, and even death, in pets. Talk to your veterinarian before you give ANY medication to your pet.

Q: What's the difference between the brand name, trade name and generic name of a medication?

A: Brand names and trade names are also called proprietary names and are just what they sound like – they are the trademarked names you recognize on the shelves and see in advertisements. The generic name, on the other hand, is the nonproprietary name of the drug and is the same for all versions (brand-name and otherwise) of that drug. An example is famotidine: there are several brand names for the drug, including Pepcid AC® , but the generic name of the drug is famotidine. If you were to buy the brand/trade name of the drug you'd purchase Pepcid AC but if you were to buy the generic version, it would just be labeled "famotidine."

Q: Is there a difference between the brand name version and the generic version of a medication?

A: For the most part, no. In both cases, law and regulations dictate that current good manufacturing practices must be followed. In addition, the United States Pharmacopeia (USP) sets standards for the quality, purity, strength and consistency of all prescription and OTC medications in the United States. The goal is to make sure that the product you purchase meets these standards. If you look closely at the drug label, you'll see "USP" printed after the drug name in the ingredients list, and sometimes it's printed clearly on the front label of the bottle/box. Based on USP standards, for example, generic famotidine is the same drug as the brand name-versions of famotidine (of the same strength) as far as the quality, purity, and consistency are concerned.

However, we have heard some anecdotal and unconfirmed reports of pets that had been receiving a brand name medication but did not do as well when given a generic version of the same medication. Although all USP versions of a drug meet the purity standards for that drug, all of the ingredients and the processes involved in making the trade name versions are often protected by patent or other intellectual property laws, and there may be differences in the minor ingredients that could produce slightly different results between the versions.

Q: Why are some spot-on flea and tick preventive medications only available through my veterinarian?

A: Some manufacturers have decided to sell their products only through veterinarians so that the veterinarian and pet owner can work together to determine the best flea and tick treatment for that pet. It's not that the product is "prescription-only" – it's that the manufacturer believes the product should only be sold through veterinarians. In addition, it seems more likely that the product will be used properly (for example, a cat won't be treated with a product labeled only for use in dogs) if the veterinarian is counseling the pet owner on appropriate use.

Q: Where can I get my pet's prescriptions filled?

A: You have several options when your pet needs a prescription medication:

  • You can get it from your veterinarian if they keep it in stock.
  • Your veterinarian can write (or call in) a prescription to a local pharmacy that stocks the medication.
  • Your veterinarian can provide a prescription so you can get the medication from an online pharmacy.

Q: If I choose to get my pet's prescriptions filled outside of my veterinarian’s office, can my veterinarian refuse to give me a prescription?

A: AVMA’s Principles of Veterinary Medical Ethics require that veterinarians provide prescriptions to clients upon request in lieu of dispensing a drug when a veterinarian-client-patient relationship exists and the veterinarian has determined that the drug is medically necessary. Additionally, most states have laws requiring veterinarians to provide prescriptions upon request.

Q: Is there a reason that I cannot take a prescription written by my veterinarian and have it filled at another veterinary clinic?

A: Most states require a veterinarian-client-patient relationship (VCPR) in order for a veterinarian to fill a prescription. However, the rules on this vary by state – a few states do allow veterinarians to fill prescriptions from other veterinarians in certain scenarios.

Q: My veterinarian is telling me that I have to bring my pet in for an examination before they'll write a prescription or authorize a refill. Why?

A: It is unethical, and, in most states, unlawful, for a veterinarian to write a prescription or dispense a prescription drug outside a veterinarian-client-patient relationship (VCPR). For more information about the VCPR, including a technical definition, see the AVMA's Principles of Veterinary Medical Ethics. For an overview of the VCPR, read our Veterinarian-client-patient relationship FAQ.

To maintain a VCPR, your veterinarian must see your pet regularly – how often depends on your pet's health. If your pet is on a prescription medicine, your veterinarian may need to reexamine your pet, check blood work, or perform other tests to monitor your pet's response to treatment and determine if the medication needs to be changed. For example, a dog being treated for hypothyroidism needs to be reevaluated regularly to make sure the dosage of medication prescribed is effective.

Q: How do I know the pharmacy is trustworthy?

A: Prior experience with a pharmacy is a good indication – ask your veterinarian if there is a pharmacy they recommend. You can also inquire with the state board of pharmacy to determine whether a pharmacy is licensed within the state and the status of the pharmacy's license.

In addition, accreditation by independent bodies can give you more information about an online pharmacy. Two examples of third-party accreditation include the National Association Boards of Pharmacy Pharmacy Verified Websites Program and, for compounding pharmacies, the Pharmacy Compounding Accreditation Board.

Q: What is the difference between a brand name or generic prescription medication and a compounded medication?

A: A brand name or generic prescription drug is approved by the FDA. A compounded drug is not an FDA approved drug. However, for a variety of reasons the use of an FDA approved product may not always be feasible. For more information on compounded medications see

Q: How will I know if there are or side effects or other problems with the medications I get from a pharmacy?

A: Don't hesitate to contact your veterinarian if you are concerned that your pet is having a problem with or a reaction to the medication. Talk to your veterinarian about the clinical signs your animal might show in case of a problem with the medication. Make sure you know what to look for, and what to do if you see it.

If you receive a shipped medication and the package is damaged or it appears to have been allowed to get too hot or too cold, contact the pharmacy immediately and notify them of the problem. If you are not sure if the medication is safe to use in that condition, contact your veterinarian.

If you have concerns or complaints about a pharmacy's practices or the quality of its products, you can report the pharmacy to your state board of pharmacy and also to the FDA.