After eye drops mouth bitter because the eyes, nose, mouth is connected, drops into the conjunctival sac of eye drops through the function of the orbicularis oculi muscle pump and tears together into the upper and lower lids near the nasal side of the tear ducts, through the upper and lower lacrimal ducts, tear ducts, nasolacrimal ducts into the nasal cavity and then into the oral cavity, so after the eye drops mouth is bitter. Usually, after using eye drops, especially atropine, hairy fruit rutaecarpine and other special effects of eye drops, we should press the root of the nose, that is, the lacrimal sac area for 2-3 minutes, so as to avoid the adverse effects of eye drops through the nasal cavity into the mouth to cause side effects.