Are azaleas poisonous to cats?
Azaleas are indeed a problem for cats and other pets. See this link from Purdue University’s Veterinary Program.
Excerpt:
“These ornamental shrubs aren’t commonly nibbled on but they can cause fatal heart problems in dogs, cats, and pet birds. Signs to watch for are similar to that of the yews and include weakness, fainting, salivation, difficulty breathing, vomiting, and diarrhea.”
According to the Handbook of Poisonous and Injurious Plants, 2nd ed., by Lewis Nelson et al. (New York Botanical Garden/Springer, 2007), all Rhododendron species, including Azaleas, contain grayanotoxins in their leaves. Honey made from the flower nectar would also be toxic.