Acetaminophen (Tylenol) if I can't get it under control without meds but I agree with the other posters about trying to figure out the root cause! For me, the main causes of headaches used to be hormones from the pill until I switched to a different form of birth control (IUD). Nowadays my headaches are mostly dry eye or allergy related so I keep eye drops on hand and take allergy meds and I'm down to headaches once every week or two. Staying hydrated and taking fish oil supplements has also helped my dry eyes.