have headache
The Spanish phrase 'tener dolor de cabeza' literally translates to 'have pain of head' in English. However, it is more naturally understood as 'have a headache'. This phrase can be used in the same situations where one would express their sufferance of a headache in English, such as 'Tengo dolor de cabeza' translating to 'I have a headache'.
After studying all day, I usually have a headache.
This sentence describes a common physical condition that might happen after a long period of concentration on a task, like studying, symbolized here by the usage of the phrase 'tener dolor de cabeza'.
When I forget to put on my glasses, I start having a headache.
In this instance, the phrase 'tener dolor de cabeza' is used to highlight a consequence of not wearing glasses for someone who needs them to see properly, which could cause headaches.
If I don't drink enough water during the day, I can have a headache.
This sentence emphasizes the importance of hydration for the body's wellbeing using 'tener dolor de cabeza' to illustrate one of the potential symptoms of dehydration.