Are the cough drops sugar free?
What are the ingredients?
Most likey your dog is having a reaction to the Menthol. You will most likely see some gastrointestinal upset to include vomiting and diahrrhea. For now please give some Plain Benedryl at 1-2 mgs per pound of body weight every 8 hours. You will want to use some cool compresses on the areas that is swollen. This will help with the allergic reaction to the cough drops. If she shows any other symtoms you will want to see the ER Vet. If the Benedryl seems to help, then follow up with the Vet tomorrow. Joan