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What is E-Cigarette Allergy?

E-cigarettes contain a large number of chemicals, including nicotine and tiny particles of metals, including heavy metals, and the liquid that the nicotine is suspended in is either propylene glycol or vegetable glycerine. Propylene glycol is the most likely culprit when dealing with inhalant allergies, however, either contact or inhalant allergies can be caused by any of the ingredients in the liquid. Food allergies are less common as the solution itself is neurotoxic when ingested, so it is more likely to poison the animal before it triggers an allergy. Symptoms of nicotine poisoning are quite different from the symptoms related to an allergic reaction and should prompt an immediate visit to the nearest veterinary clinic.

Cats may on occasion develop either contact or respiratory allergies in connection with E-cigarettes.

Symptoms of E-Cigarette Allergy in Cats

Symptoms of allergies in cats are typically exhibited as skin problems, regardless of the type of allergy. Allergy symptoms caused by secondhand vaping are likely to be centered on the head and ears of the cat but may show up anywhere on their body. Allergy symptoms due to direct contact with the fluid will generally start at the point of contact and spread from there. These symptoms may include: 

  • Bumps and scabs on the skin 
  • Hair loss
  • Overgrooming
  • Pulling out tufts of hair
  • Scabbing
  • Swollen skin
  • Twitching skin

Cats who are experiencing the disorder due to inhalation may also exhibit watery eyes, difficulty breathing, runny nose, bad breath, and coughing. 


There are several components to e-cigarettes that cats can develop a sensitivity or allergy to. Two of the more problematic ingredients may include: 


As well as being a relatively allergenic substance, moderate to large amounts of nicotine is neurotoxic. In the amounts that most felines would be exposed to by secondhand vapor, it is more likely to act as an allergen than a toxin.

Propylene Glycol

This common chemical is employed as a food additive, in toothpaste and mouthwash products, and as a solvent for colors and flavorings in foods. It is also the basis of many vaping liquids, and although relatively safe for humans it can be particularly problematic to cats as it increases the amounts of Heinz bodies found in their blood, but unless you are blowing the vapor directly in their faces, it is unlikely to be enough to cause a toxic reaction. The most common allergy-related to propylene glycol is a contact allergy as it can cause dermatitis to those who are sensitive to it. As cats often lick themselves to clean themselves, this contact allergy could extend into the mouth and throat area.

Causes of E-Cigarette Allergy in Cats

Cats can develop either contact or respiratory allergies to the vapor if it activates the immune system. Allergies are the result of an overly aggressive response by a specialized type of immune cell known as a mast cell to a protein present in the e-cigarette liquid. Both naturally occurring and synthetic proteins are capable of stimulating the mast cells to release histamine, which is responsible for the majority of the itching and swelling that is characteristic of an allergic response. E-cigarettes can cause reactions either due to inhaling the vapor, due to the vapor or liquid landing on the skin or due to the cat licking it off of their fur.

Diagnosis of E-Cigarette Allergy in Cats

The veterinarian examining your cat will most likely be prompted by the condition of the skin to collect a sample from an affected area using a technique known as skin scraping. These samples will then be evaluated by cutaneous cytology, the microscopic examination of the skin cells in order to detect infestations of microorganisms such as mites, bacteria, or yeast. Standard diagnostic tests such as a urinalysis, complete blood count, and biochemical profile, will also be completed to rule out certain diseases and may reveal an overabundance of eosinophils, a type of blood cell that may signify an allergic reaction has recently taken place. 

The symptoms that the cat is experiencing combined with the lack of evidence of other disorders may help to make a preliminary diagnosis. At this point, a patch test, also referred to as an intradermal skin test, may be recommended and minuscule amounts of the antigens that the veterinarian suspects, include the nicotine and propylene glycol, will be injected under the skin in order to induce a localized reaction.

Treatment of E-Cigarette Allergy in Cats

The best way to treat a feline allergy to the vapor or liquid in E-cigarettes is to eliminate it from the cat’s environment completely. If the allergy is to only the propylene glycol, then switching to a brand that uses vegetable glycerine instead may eliminate the response, but if it is to the nicotine or one of the other components you may need to avoid vaping in the house entirely. In many cases, allergy symptoms will continue for a few weeks or months after the chemical has been eliminated from the animal’s environment. 

There are a number of effective antihistamine options formulated specifically for cats, and there are also some human antihistamines that can safely be administered to cats as well. It is critical, however, that you never give your pet human medications without the advice and supervision of a veterinarian as even those that are safe for cats to use may require species-specific adjustments to the dosage to remain safe. Hydrocortisone salves and shampoos may also help to relieve skin discomfort, although it is important to prevent your pet from licking off and ingesting these preparations. Severe cases that are unresponsive to antihistamines or hydrocortisone preparations may respond to corticosteroid injections or oral tablets. Although cats can develop side effects from the corticosteroids, it is much less common than it is for dogs.

Recovery of E-Cigarette Allergy in Cats

Allergies may take quite some time to clear up, and this can lead to some additional complications and to stop animals from constantly itching and scratching themselves, some cats may require an Elizabethan collar. In some cases, inhalant allergies can lead to respiratory infections, and secondary skin infections are not uncommon on skin that has been marred by an allergic reaction. When this occurs, either topical or oral antibiotic will be required to clear the infection, and it is crucial to complete the full measure of antibiotic medication even if the symptoms appear to have subsided. Discontinuing antibiotic medications before the infection has been completely eradicated may cause the infection to reoccur.