Why does it sting when lemon juice enters a cut finger?

Lemon juice contains citric acid, which can irritate nerve endings in a cut or open wound. When the acidic juice comes into contact with exposed nerve endings, it triggers a painful sensation. Additionally, the acidity disrupts the skin's natural pH balance, further exacerbating the sting. This combination of factors causes the sharp, stinging pain associated with lemon juice on a cut.