Project Description

Imidazoline decongestants are an OTC class of drugs commonly used for nasal congestion or in eye medications to relieve redness and inflammation. Products commonly used are Afrin and Visine.


Drugs in this class include:

  • oxymetazoline
  • tetrahydrozoline
  • naphazoline
  • tolazoline

Well-meaning owners may consider giving these products to their pets to treat ailments, particularly eye complications. Due to toxicity risks, always consult your veterinarian before giving your pet any medication. Poisoning may also occur if a pet chews on the vials containing these products.

Signs and symptoms of toxicity: severely low blood pressure, decreased heart rate, weakness, fatigue, depression, agitation, vomiting, tremors, and seizures. Symptoms may occur within 15 minutes of ingestion.

Toxic consumption: There is no established toxic threshold for pet consumption. All incidents of accidental exposure should be reported immediately.

– Fitzgerald KT, Bronstein AC, Flood AA. Over-the-counter drug toxicities in companion animals. Clin Tech Small Anim Pract 2006; 21(4):215-226.
– Osweiler, G, et al. (2011). Blackwell’s five-minute veterinary consult clinical companion. Small Animal Toxicology. [Kindle version]. Retrieved from