To become swollen (typically due to inflammation, injury, or allergy); a body part enlarges and may become painful or hard.
虫に刺されて足が腫れて痛い。
My leg is swollen and painful from an insect bite.
花粉症で目が腫れて赤くなった。
My eyes became swollen and red because of hay fever.
転んで打ったところが翌日大きく腫れた。
The spot I hit when I fell swelled up a lot the next day.