Eyelid swelling in summer may be caused by drinking too much water, or it may be caused by allergic blepharitis or mosquito bites. 1. Edema: summer is hot, so it is easy to sweat, but also increase the amount of water intake, if you drink a lot of water in a short period of time, especially before going to bed, the amount of water intake exceeds the limit of kidney drainage, excess water will be retained in the body, the patient may appear to be swollen eyelids. 2. Allergic blepharitis: There are a lot of pollen particles and dust floating in the air in summer, and allergic patients may have allergic reactions after contacting allergens, which may lead to swelling, redness, itching and other discomforts of the patient’s eyelids. 3. Mosquito bites: If the patient’s eyelids appear obvious redness and swelling, it may also be caused by mosquito bites, and the patient may also be accompanied by eye itching, pain and other discomfort. It is recommended that patients with obvious eye swelling consult a doctor in time to assess the condition and follow the doctor’s instructions for treatment.