Well, of course, the headache can lead to dilated pupils. First, you should know that high pressure can cause dilated pupils. So when you have headache, it will increase your blood pressure, and then you will get high blood pressure. Finally, it can affect your eyes, and turn to dilated pupils. So just try some ways to heal your headache symptom. Also, anxiety, drug use, illness, and trauma are also the factors which will cause this disease. When the pupils, the black part of the eye are bigger than normal, we will see dilated pupils look like a big black circle, at that moment, you may get dilated pupils.