Miss C visits yоur phаrmаcy requesting sоme аdvice fоr headache. She has had this type of headache before but hasn’t sought any medical advice. She describes her vision being “pixilated” with bright dots on the periphery of her vision. This is followed by nausea and a severe throbbing headache on one side of her head. She confirms that she has had no recent changes to medications. In addition to giving treatment recommendations, you advise that her current contraceptive pill may no longer be appropriate for her. Based on the information given, why would Mercilon no longer be suitable for her?