It is indeed dangerous for a cat to lick external parasite medication. External parasite medications usually kill parasites through skin absorption, and these medications are generally relatively safe for cats. However, if ingested or in large quantities, they can pose a danger to the cat.

Cat owners should closely monitor their cat's health. If abnormal symptoms such as vomiting or diarrhea occur, please contact a veterinarian immediately. When using external parasite medication, ensure the cat does not lick its skin; a collar can be used.
To prevent this, it is recommended to follow the correct dosage and usage method when using external parasite medication, and to take appropriate measures to prevent the cat from licking it.