Histalix Expectorant Syrup 150 mL is an expectorant cough syrup that helps loosen phlegm while diphenhydramine reduces cough and allergy-related upper-airway symptoms. Its confirmed composition is Each 5 mL contains diphenhydramine hydrochloride 14 mg, ammonium chloride 135 mg and levomenthol 1.1 mg; contains sucrose.

For adults and adolescents 12 years and older, take 5–10 mL every four hours when needed, with no more than four 10 mL doses in 24 hours. It can cause marked drowsiness; avoid alcohol and driving.

Drowsiness, dizziness, dry mouth, blurred vision, nausea, constipation or difficulty urinating may occur. Seek urgent help for confusion, severe palpitations, allergic swelling or breathing difficulty.