BACKGROUND: Health risk behaviours such as smoking and binge drinking track from adolescence to adulthood. Medicine use is associated with smoking and binge drinking among adolescents. Whether medicine-use behaviour tracks from adolescence to adulthood is unknown. AIM: To examine tracking of medicine use for headache from age 15 to 19 to 27. METHODS: A national random sample of 15-year-olds (n = 996) was followed up after four and twelve years respectively in a longitudinal study in Denmark; 614 persons completed questionnaires in all three waves. The main outcome measure was medicine use for headache within the past 14 days. RESULTS: Medicine use for headache was common in all age groups and more females than males used medicine in all three age groups: 34.9% vs. 18.0% at age 15, 45.4% vs. 22.1% at age 19 and 44.3% vs. 29.5% at age 27. The risk of using medicine for headache at age 27 increased if medicine was used at age 15 or 19. However, use increased substantially if medicine for headache was used at both age 15 and 19 (OR = 5.83, 95%CI: 1.99-17.14 for males and OR = 4.67, 95%CI: 2.59-8.43 for females). CONCLUSION: Medicine use for headache is a behavioural pattern that may track from adolescence into adulthood.