Do side effects of strattera (atomoxetine) last more than a day?

Likely will. Strattera (atomoxetine) is not a stimulant but in the class of antidepressants. It needs to be taken daily and takes time to build up both blood concentrations and effects. Inititally, side effects such as nausea or daytime drowsiness by worsen, especially if dose is being increased. Some se well may carry over to next day. Usually, over time, se diminish and often disappear, though.