Fluorouracil cream is prescribed for people to apply to their skin to treat a number of conditions. These include warts; skin cancers such as certain forms of basal and squamous cell carcinoma; patches of scaly skin called actinic keratoses that usually come from too much sun exposure and can turn into cancer over time if not treated; and vitiligo. Dogs are dying from the cream, the FDA reports. Often it’s because they get into the tube itself, but even licking the cream from a person’s skin can cause illness. And many dogs like to lick and taste the topical medicines and other lotions that people apply.

Signs of fluorouracil poisoning can begin within 30 minutes of a dog’s ingestion of the drug. They include vomiting (sometimes with blood), seizures, tremors/shaking, difficulty breathing, lethargy, drooling, diarrhea (again, sometimes with blood), and incoordination/lack of balance. Even if a dog is rushed to the veterinarian’s office after consumption of this topical, which is the right course of action, he may not make it.

The consequences are so dire and the FDA has now received enough reports that the agency has asked manufacturers of the topical to include the following warning on labels:

“May be fatal if your pet licks or ingests. Avoid allowing pets to contact this tube or your skin where [name of specific fluorouracil product] has been applied. Store and dispose out of the reach of pets.”

The drug is sold under the brand names Carac, Efudex, Tolak, and Fluoroplex. It is also sold under the generic name Fluorouracil Cream USP, 5%.

Can’t be too careful

For your part, always keep flourouracil (and all medicines, for that matter) out of reach. (For a tall dog, the top of your nightstand is not out of reach.) In addition, throw away or wash anything used to apply the medicine, such as gloves or cotton-tipped applicators. Wash your hands well after applying the medicine, too. And avoid leaving any medicine residue on your hands, clothing, carpeting, or furniture. Finally, don’t let your dog lick the spot on your skin.

Your Dog Can Die From Licking Your Topical Medicine originally appeared in the Your Dog newsletter from Tufts University.