Cough drops are meant to be dissolved slowly in the mouth, not chewed or swallowed whole. They are usually sold in wrapped individual pieces inside a bag or box.
常見錯誤
I took a spoonful of cough drop before bed.
I took a spoonful of cough syrup before bed.
'cough drop' is a hard lozenge, not a liquid medicine.
She swallowed the cough drop with water.
She let the cough drop dissolve slowly in her mouth.
Cough drops are designed to dissolve in the mouth, not to be swallowed like a pill.