Hi there, every time after a run or work out, i get a bad headache. this happens even if i drink a lot of water before, during abs after the work out. what could be causing it?

Electrolytes: Electrolyte imbalances can lead to headaches after workouts. Try substituting an electrolyte solution for every other bottle or glass of water throughout the day. You should see a difference right away. If the symptoms persist, though, check in with your GP for an exam to rule out other causes such as Blood Pressure problems, etc.

Many possibilities: One consideration is exercise induced migraine headaches, which can be handled preventatively. Might respond to magnesium supplements.