Stephanie Johnson is a 32 year old vet who saw one of your colleagues six weeks ago with troublesome headaches. You see from her notes that they discussed the nature, timing and severity of headaches, as well as, possible triggers and had agreed to lifestyle changes and review in a few weeks with a headache diary. Stephanie also has mild anxiety and dysmenorrhea. Her BMI is 32. The headaches were throbbing in nature and mainly unilateral with some photophobia. Miss Johnson has come to see you today with her headache diary and is wondering if there is any treatment she could try as she has had a further headache since last being seen. Looking at Stephanie’s headache diary you can see that episodes appear to be triggered by the onset of menses. There are no red flags in the history. She takes Desogestrel for contraception.
Given the likely diagnosis what is the most suitable first line treatment?