If your canine friend finds a cough drop or a package of them lying around, he is likely to try them out. Any small, hard object, such as a cough drop, is a choking risk for dogs of all ages. As for toxic effects, your main concerns are the ingredients xylitol and menthol. Both are commonly found in cough drops and can impact your dog's health.
Xylitol, an artificial sweetener often found in cough drops, is toxic to dogs. One cough drop is likely to cause only minor gastrointestinal upset, but if your dog's behavior changes, seek immediate veterinary assistance. Xylitol can significantly lower your dog's blood pressure, causing loss of coordination, seizures and motor activity depression. Liver damage is also a risk of xylitol consumption.
Menthol is another ingredient with potentially toxic effects. Menthol is an irritant to the tissues of the mouth and digestive tract, so your dog may experience mild vomiting or diarrhea, or lie around with a belly ache. As with xylitol, seek immediate veterinary assistance if your dog's behavior changes, such as if he's unable to stay awake or has trouble walking. To a newborn puppy, menthol can be deadly, because the cooling action of the cough drop depresses the lungs' ability to exchange oxygen, which can lead to respiratory depression.