Redness at the tail of the eye is mostly caused by acute irritation, such as external stimulation, acute infection, allergy and other factors. 1. External stimulation: the patient’s tail of the eye scratching and itching discomfort, the patient may not consciously repeatedly rub the tail of the eye, resulting in the patient’s tail of the eye localized redness, is a normal phenomenon. 2. Acute infection: If the skin at the corner of the patient’s eye is flushed and accompanied by blisters, pain and other discomforts, it may be caused by viral infection. If the patient’s eye tissue bacterial infection can lead to local inflammation, such as conjunctivitis, keratitis, etc., the patient may also appear local redness, swelling, burning, pain and other manifestations. 3. Allergic diseases: if the patient’s tail of the eye by mosquito bites, cosmetic stimulation, etc., allergic reactions can occur, the patient may be manifested in the tail of the eye redness, swelling, pain, skin epidermal damage and other symptoms. It is recommended that patients with obvious redness and swelling of the tail of the eye should consult the hospital in time to assess their condition and under the guidance of the doctor.