An excessive reaction to a situation or stimulus; often used for emotional responses or physiological responses (e.g., allergies).
上司の一言に過剰反応してしまい、後で冷静になった。
I overreacted to my boss's remark and calmed down later.
薬に対する過剰反応で蕁麻疹が出た場合はすぐに医師に相談するべきだ。
If you develop hives from an excessive reaction to a medication, you should consult a doctor immediately.
ネット上では小さな出来事が過剰反応を招きやすい。
On the internet, small incidents tend to trigger overreactions.