After dropping eye drops, the mouth is bitter, because the eye drops into the mouth, eye drops into the conjunctival sac of the eye, eye drops will be absorbed through the two lacrimal openings located in the inner side of the upper and lower eyelids, that is, tear ducts through the upper and lower lacrimal ducts, lacrimal ducts and nasolacrimal ducts drainage to the nasal cavity, oral cavity, after the eye drops into the mouth, our mouth will be bitter. Therefore, usually, the doctor will ask the patient after dropping eye drops, compression of the lacrimal sac is also the root of the nose on both sides of 2-3 minutes, in order to maximize the blockage of eye drops into the nasal cavity, the oral cavity to reduce the side effects brought about by the eye drops, especially children dropping atropine eye drops pupil dilation, especially should pay attention to the lacrimal sac should be compressed for 2-3 minutes.