Ambroxol
Ambroxol is a mucolytic and expectorant. It stimulates the airway glands and the movement of the cilia that sweep mucus upwards, and it supports surfactant production, so secretions become thinner and easier to bring up. It is used for a cough with thick phlegm during airway infections.
It is taken with food, spread across the day, and enough water matters as much as the drug itself — without fluid the loosened mucus stays where it is. Because it makes a cough more productive rather than quieter, it does not sit well with something meant to suppress coughing at the same time. Mild nausea, stomach discomfort or an altered sense of taste can occur and generally settle.
Rash, blistering or peeling skin, swelling of the face or mouth, or breathing that becomes harder are reasons to stop guessing and see a doctor; so is a cough that persists or comes with fever after a course of treatment.
Reference information, not medical advice. Discuss any change with your doctor.