基本结论
“Headache” 既可作可数名词，也可作不可数名词，具体取决于语境。
作为可数名词（a headache / headaches）
当表示“一次头痛”或“多次头痛发作”时，“headache” 是可数的：
• I had a terrible headache last night.
• She gets headaches every time she reads without glasses.
• She gets headaches every time she reads without glasses.
作为不可数名词（headache）
当泛指“头痛”这种症状或不适感（不强调次数）时，通常用作不可数名词：
• Stress can cause headache.
• He suffers from chronic headache.
• He suffers from chronic headache.
不过在现代英语中，即使泛指，也常使用复数形式 “headaches”，因此不可数用法相对较少见。
引申义：麻烦事（可数）
“Headache” 还常用于比喻义，表示“令人头疼的人或事”，此时总是可数：
• This project has been a real headache.
• Dealing with bureaucracy is always a headache.
• Dealing with bureaucracy is always a headache.
常见误区
❌ 错误：I have headache.
✅ 正确：I have a headache.（因为这里指“一次头痛”，必须加冠词）
✅ 正确：I have a headache.（因为这里指“一次头痛”，必须加冠词）
在表示“我头痛了”时，英语习惯说 “I have a headache”，而不是 “I have headache”。
更多例句
• The noise gave me a headache.
• Migraines are more than just bad headaches.
• Filing taxes is such a headache!
• He’s been a constant headache for the management.
• Do you often get headaches in the morning?
• Migraines are more than just bad headaches.
• Filing taxes is such a headache!
• He’s been a constant headache for the management.
• Do you often get headaches in the morning?