Tegan uses sublingual nitroglycerin for angina and has been warned to store it in a glass container with a tightly fitting screw top away from heat, because it is so sensitive to environmental conditions. How can she tell if, despite her efforts, the medication has lost its potency?

Tegan uses sublingual nitroglycerin for angina and has been warned to store it in a glass container with a tightly fitting screw top away from heat, because it is so sensitive to environmental conditions. How can she tell if, despite her efforts, the medication has lost its potency? 


She will get a severe rash and itching.
The medication will change color and smell odd.
She will not feel tingling when she places it under her tongue.
Her vision will blur and her mouth will get dry.


Answer: She will not feel tingling when she places it under her tongue.