Candesartan for Migraine Prevention:

1. Signed informed consent
2. Episodic migraine with or without aura according to ICHD-3 criteria
3. At inclusion, patients should retrospectively have from 2 to 8 migraine attacks per month during the last 3 months. This frequency must be confirmed in the headache diary before randomization to treatment.
4. Debut of migraine at least one year prior to inclusion
5. Start of migraine before age 50 years
6. No use of other migraine prophylactics during the study
7. For women of child-bearing potential, use of highly effective contraception.

Exclusion Criteria:

1. Interval headache not distinguishable from migraine;
2. Chronic migraine, chronic tension-type headache, medication overuse headache or other headache occurring on ≥ 15 days/month
3. Pregnancy, planning to get pregnant, inability to use contraceptives, lactating
4. Clinical information on or signs of cholestasis or decreased hepatic or renal function. If in doubt, relevant blood tests should be performed
5. High degree of comorbidity and/or frailty associated with reduced life expectancy or high likelihood of hospitalization, at the discretion of the investigator
6. Hypersensitivity to candesartan
7. History of angioneurotic oedema
8. Current use of antihypertensive medication
9. Current use of potassium supplements
10. Current use of spironolactone
11. Primary hyperaldosteronism (Conn's syndrome)
12. Significant psychiatric illness
13. Use of medicines for migraine prophylaxis less than 4 weeks, or of botulinum toxin less than 16 weeks, prior to start of study
14. Having tried ≥ 3 prophylactic drugs against migraine during the last 10 years
15. Previous use of candesartan
16. Requiring detoxification from acute medication (triptans, opioids)
17. Consistently failing to respond to any acute migraine medication
18. Alcohol or illicit drug dependence.
19. Inability to understand study procedures and to comply with them for the entire length of the study