What does 頭痛 (ずつう, zutsuu) mean?

頭痛(ずつう)がひどいので薬(くすり)を飲(の)んだ。

My headache was so bad that I took medicine.

朝(あさ)から頭痛(ずつう)がして仕事(しごと)にならない。

I've had a headache since morning and can't get any work done.