There is no clinically preferred eye drop for allergic conjunctivitis in adults. Commonly used drugs for adult allergic conjunctivitis include antihistamines, mast cell stabilizers, glucocorticoids, and mixtures of antihistamines and mast cell stabilizers. 1. Antihistamines: they can competitively block histamine receptors and reduce itching and redness of the eyes, and the common ones are emetine fumarate and azelastine hydrochloride eye drops. 2. Mast cell stabilizers: can stabilize mast cells and eosinophils, inhibit mast cell degranulation and histamine release, thus inhibiting the occurrence of allergic conjunctivitis, common color sodium glycolate eye drops, lodosamide eye drops, etc.. 3. Glucocorticoids: can effectively inhibit the activation of a variety of immune cells and the release of inflammatory response mediators, applicable to severe allergic conjunctivitis and recurrent patients, common fluticasone eye drops, tobramycin dexamethasone eye drops. 4. A mixture of antihistamines and mast cell stabilizers: the combination of the two drugs is more conducive to treatment, commonly used Olopatadine eye drops, azelastine hydrochloride eye drops and so on. Adult allergic conjunctivitis, patients can choose eye drops under the guidance of the doctor, to avoid the adverse consequences of blind medication.