Cold and Flu Medications Dangerous for Pets

Laurie Anne Walden, DVM

Many over-the-counter (nonprescription) cold and flu medications contain ingredients that are toxic to dogs and cats. Keep all medications out of reach of your pets, and check with your veterinarian before giving a pet any medication—even remedies that are safe for children.
 
Cold medications are often sold as combination or multisymptom products containing more than 1 active ingredient. If your veterinarian recommends giving your pet a nonprescription medication, read the product label carefully to be sure it contains only the medication your veterinarian has approved.
 
Ingestion of some cold and flu products (especially oral decongestants, nasal sprays, eye drops, and pain relievers) is a medical emergency in animals. If your pet is exposed, contact a veterinary clinic or pet poison hotline:

• ASPCA Animal Poison Control: 888-426-4435, https://www.aspca.org/pet-care/animal-poison-control
• Pet Poison Helpline: 855-764-7661, https://www.petpoisonhelpline.com/

 
Oral Decongestants
Decongestants are often added to allergy medications and combination cold and cough remedies. If your veterinarian has recommended a nonprescription antihistamine for your pet, be sure that the product you use does not contain a decongestant. Look for label wording like congestion, stuffy nose, runny nose, multisymptom, or sinus pressure; these probably mean that the product includes a decongestant. Names of products containing decongestants might end in D (for example, Claritin-D and Mucinex D) or PE (as in Sudafed PE).
 
Pseudoephedrine and phenylephrine are the most common oral (by-mouth) decongestants. Both are dangerous for animals. In the United States, pseudoephedrine is sold without a prescription but with restrictions: it’s sold only in limited quantities, is usually kept behind the pharmacy counter or in a locked cabinet, and requires that the buyer show identification. If you’re not sure of the ingredients of your cold medication, knowing whether you took it from an open shelf or had to ask the pharmacist for it will help you figure out whether it is likely to contain pseudoephedrine.
 
Pseudoephedrine stimulates the cardiovascular system and certain nervous system pathways. It reduces nasal congestion by shrinking tiny blood vessels in the nose. It has a very narrow margin of safety in animals, meaning that a small dose can have serious consequences for a dog or cat. Symptoms of pseudoephedrine toxicity include the following:

• Nervousness
• Hyperactivity
• Panting
• Rapid heart rate
• Tremors
• Possibly death

 
The time of symptom onset depends on the formulation. With immediate-release products, symptoms can begin within minutes of ingestion. With extended-release products, symptoms might not appear for several hours.[1]
 
Phenylephrine is an ingredient in oral cold remedies, hemorrhoid creams, nasal sprays, and some eye drops. Animals are exposed by swallowing the product. The most common symptom is vomiting; other symptoms are similar to those of pseudoephedrine toxicity. Phenylephrine is not as toxic as pseudoephedrine at low doses.[2]
 
Nasal Sprays and Eye Drops
Oxymetazoline, tetrahydrozoline, naphazoline, and xylometazoline are imidazolines, a class of decongestant used in nasal sprays and eye drops (examples are Afrin and Visine). Animals—usually dogs—who chew the bottle and ingest the liquid can develop vomiting, lethargy, incoordination, slow heart rate, tremors, and coma. Imidazoline ingestion can be fatal.[3]
 
Some nasal sprays contain xylitol, a sweetener that is safe for humans but toxic to pets. Plain saline nasal rinses with no ingredients other than water and salt should be safe if accidentally ingested, but don’t squirt them up your pet’s nose.
 
Pain Relievers
Combination cold and flu products commonly contain pain relievers, most of which are unsafe for dogs and cats. Acetaminophen is extremely toxic to cats even at low doses. It causes liver failure, damage to hemoglobin in red blood cells, and death. It can also cause liver damage in dogs. Ibuprofen and naproxen are in a class of pain relievers called nonsteroidal anti-inflammatory drugs. In dogs and cats, these medications can cause stomach ulcers, digestive tract bleeding, kidney damage, and liver damage.
 
Cough Suppressants and Cough Drops
Dextromethorphan is an antitussive, or cough suppressant, included in many cough remedies and combination cold and flu products. Animals who ingest dextromethorphan can develop vomiting, lethargy, rapid heart rate, and seizures.[4]
 
Potentially toxic ingredients in cough drops include xylitol, which causes a dangerous drop in blood sugar in dogs, and benzocaine, which can cause upset stomach and possibly damage to red blood cells.
 
“Natural” Remedies
In high enough doses, zinc can damage red blood cells. Essential oils like menthol, camphor, and eucalyptus oil can cause skin reactions if applied topically. If swallowed or absorbed through the skin, these oils can cause symptoms ranging from vomiting to nervous system problems.
 
References
1. Pseudoephedrine toxicity in pets. ASPCApro. Accessed January 9, 2021. https://www.aspcapro.org/resource/pseudoephedrine-toxicity-pets
2. Wegenast C. Toxicology brief: phenylephrine ingestion in dogs: what's the harm? DVM360. November 1, 2012. Accessed January 9, 2021. https://www.dvm360.com/view/toxicology-brief-phenylephrine-ingestion-dogs-whats-harm
3. Imidazoline. Pet Poison Helpline. Accessed January 9, 2021. https://www.petpoisonhelpline.com/poison/imidazoline/
4. Dextromethorphan ingestion in pets. ASPCApro. Accessed January 9, 2021. https://www.aspcapro.org/resource/dextromethorphan-ingestion-pets
 
Photo by Shlomi Platzman

---