Sudden swelling of the left eyelid can be seen in blepharoconjunctiva, allergy, folliculitis and other diseases. 1. Blepharoconjunctiva: also known as pinhole, granuloma, etc., is a purulent inflammation caused by bacterial infection, including external blepharitis and internal blepharitis, the main symptom is the local eyelid redness, swelling, heat, pain, and some patients will have a yellow pus head, to maintain local hygiene, the use of levofloxacin and other drugs for treatment. 2. Allergy: pay attention to find allergens, may be due to mosquito bites, dust mites and other allergens, the main treatment is anti-allergy treatment, can use loratadine and other drugs. 3. folliculitis: most because of improper cleaning accompanied by bacterial infections caused by the majority of localized pustules, the main treatment is anti-infection treatment, can use mupirocin ointment and other medication. The left eyelid suddenly swollen, to timely medical treatment, accept the treatment, the drugs need to follow the doctor’s instructions reasonable application.