An outstanding scientific question, that merits further investigation, is whether dilation of intracranial arteries is implicated in the pathogenesis of cephalic pain in migraine. Here, we hypothesize that experimentally-induced dilation of intracranial arteries using intake of sildenafil (a potent vasodilator) can induce cephalic pain with migraine-like features in people with migraine, who prior to the infusion are administered erenumab (anti-calcitonin gene-related peptide (CGRP) receptor monoclonal antibody.

Inclusion Criteria:

• Participant has provided informed consent prior to initiation of any study-specific activities/procedures.
• Age ≥18 years upon entry into screening.
• History of migraine without aura for ≥12 months with a frequency of 1-5 migraine attacks per month before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018), based on medical records and/or patient self-report.

Exclusion Criteria:

• History of any primary headache disorder other than migraine without aura, or tension-type headache with a frequency of ≥5 headache days per month before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018), based on medical records and/or patient self-report.
• History of any secondary headache disorder before screening according to the International Headache Society (IHS) Classification ICHD-3 (Headache Classification Committee of the International Headache Society, 2018) based on medical records and/or patient self-report.
• Intake of prophylactic migraine medication within ≤30 days or 5 plasma half-lives (whichever is longer) prior to screening.
• Prior intake of therapies targeting the CGRP signaling pathway, including anti-CGRP ligand monoclonal antibodies, anti-CGRP receptor monoclonal antibodies, and small molecule CGRP receptor antagonists.
• The participant is at risk of self-harm or harm to others as evidenced by past suicidal behavior.
• History or evidence of any other clinically significant disorder, condition, or disease (with the exception of those outlined above) that, in the opinion of the investigator will pose a risk to participant safety or interfere with the study evaluation, procedures or completion.
• Female participants of childbearing potential with a positive pregnancy test assessed at screening or day 1 by a urine pregnancy test.
• Female participants who are pregnant or breastfeeding or plan to become pregnant or breastfeed during participation in the study.
• Evidence of current pregnancy or breastfeeding per participant self-report or medical records.
• Participants likely to not be available to complete all protocol-required study visits or procedures, and/or to comply with all required study procedures to the best of the participants' and investigator's knowledge.