Introducing Mucinex® InstaSoothe Sore Throat + Pain Relief Elderberry & Wild Cherry Flavor Medicated Drops. Show your sore throat who's boss with our 3-in-1 formula that is Clinically Proven To Numb Pain Fast so you can get back to your day. Each medicated drop contains the active ingredient Hexylresorcinol, which helps to relieve occasional minor irritation and pain associated with sore throat, sore mouth and canker sores. This Powerful sore throat oral pain reliever starts to work in seconds & lasts for hours. FSA (Flexible Spending Account) and HSA (Health Savings Account) eligible. Save up to 30%. Cover out-of-pocket expenses with pre-tax dollars.