There’s not much you can’t buy online these days, including medication for your pet. But one-click shopping isn’t always a safe way to stock up on heartworm tablets or tick and flea prevention products.

Don’t put your dog or cat at risk. Read on before clicking “place order.”

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You don’t always get what you ask for

“Not all Internet sites that sell drugs for pets represent legitimate pharmacies,” says Juli Putnam, a spokesperson for the Food and Drug Administration (FDA). Many of these advertise discounted pet meds, but saving money this way could be disastrous for an animal. The FDA’s Center for Veterinary Medicine has found that some companies sell medication that hasn’t been approved or drugs that are “counterfeit.”

What’s more, pet meds purchased from a website may be mislabeled or have expired by the time you order them. And purchasing pet medication from a foreign Internet pharmacy raises the risk of receiving drugs that don’t have FDA approval.

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You leave your vet out of the equation

Some shady online pet pharmacies will dispense medication based on a form filled out by a pet owner. Warns Putnam: “Giving a pet prescription drugs without veterinary involvement may put the animal’s health in danger.”

This applies even to routine preventative drugs, particularly heartworm medication, which both dogs and cats should get monthly. If you miss a dose, or you’re even just late with it, your pet could develop heartworm disease, which is potentially fatal. At the same time, giving heartworm preventive medication to a pet that has the disease could lead to rare but potentially fatal side effects, according to the National Heartworm Association. In other words, don’t allow your pet’s heartworm medication to run out and then order more online and resume giving it without seeing your vet.

Anti-inflammatory medications (NSAIDs) for pain are another type of drug that pet owners often are tempted to purchase on the Internet. NSAIDS should be prescribed by a veterinarian in order to get the dose correct. And a pet that’s being given NSAIDS needs to be monitored closely, cautions the FDA.

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Safe buying practices

According to the American Veterinary Medical Association, getting medication directly from your pet’s doctor has advantages. The drugs are often in stock, so you don’t have to wait for delivery. They’re handled properly (for example, stored at the correct temperature), which can be a concern when a drug is shipped in the mail.

When you buy medication from the vet she can also demonstrate how to give it to your pet if it’s tricky, and answer your questions.

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If ordering medication online for your pet is truly the most convenient option for you, it’s possible to do it safely. Ask the vet, or local veterinary hospital, to recommend a reliable online site.

If you have to search for a safe site on your own, look for the Vet-VIPPS seal, which stands for Veterinary-Verified Internet Pharmacy. This guarantees that the company you’ve chosen meets the criteria required for producing and dispensing pet meds.

Report fraud

If the worst should happen and your pet reacts badly to a medication you ordered online, alert your veterinarian. Besides treating the animal’s side effects, the doctor help you get in touch with the FDA.

“Adverse drug reactions are supposed to be accompanied by a report from the company that manufacturers it,” says Putnam. By relaying your pet’s reaction, you might be helping to save other pets from suffering the same outcome.

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Jennifer Kelly Geddes is a New York City-based writer and editor who specializes in parenting, health and child development. She’s also the mom of two teen girls.