Suicide emerges as a threat to national health of USA with Whites being at extra risk. More information is needed regarding the increased suicide among Whites to improve national suicide prevention strategies. This study aims to characterise the age pattern of suicide among Whites by suicide methods adjusting for time period and birth cohort.

Suicide mortality data by age of 15–84 years during 1999–2017 were derived from the Wide-Ranging Online Data for Epidemiological Research, prepared by US Center for Disease Control and Prevention. Mortality data for three common suicide methods, firearms, suffocation and poisoning were analysed using the age–period–cohort (APC) model. Period–cohort adjusted mortality rates by age were estimated based on results from APC modelling.

Period–cohort adjusted rates indicated that the overall age pattern for males contained five phases, including three increasing phases (ages 15–20, 30–50 and 65+), connected by two declining phases (ages 20–30 and 50–65); and the age pattern for females was a parabolic with an increasing phase from 15 years of age up to 50, followed by a declining phase after age 50. Furthermore, the age pattern for different suicide methods differed substantially for males, but did not for females. Among males, suicide by firearms contained two rapid increasing phases, one during adolescence and another in older ages; suicide by suffocation showed a high plateau across an age span from 20 to 55 years; and suicide by poisoning followed a parabolic, increasing by age up to 45 before it declined. Age patterns revealed by the unadjusted crude rates were biased because of significant linear period effect and W-shaped cohort effect.

This study is the first to quantify the age patterns of suicide by different methods for US Whites using period–cohort adjusted rates. Study findings provide valid evidence supporting precision interventions to reduce the extra suicide mortality among Whites by targeting specific age ranges with different suicide methods.