Is that while the medication is at its peak, or more toward the tail end of the cycle? The extended amphetamine release Vyvanse, for example, can leave you feeling tired after it wears off. Especially on "vacations", like weekends or other extended periods, until you readjust. Such exhaustion would likely shorten anyone's temper, but especially someone with ADHD.
All I gotta say, a good specialist will definitely attempt to go through different medications with you, as what works great for some people might have side effects for others. And there are new ADHD medications being released too, some of which end up working fabulously for people who previously couldn't find one that works for them without any impairing side effects.
For me it's while it's at its peak. I personally use IR as opposed to XR. This was because I personally have a high propensity for insomnia (to the point that if I have coffee after like 2 or 3 PM I risk not sleeping). So I essentially am prescribed to take it twice a day but rarely go for the second dose. If I do take the second dose I have an insanely productive day but often get no sleep.
Back to the topic of the irritability/temper, yeah it's basically when it's active. Afterwards I'm a bit tired but otherwise totally kosher. For context, I am also on a very low dose of 5 mg. 10mg starts putting me on "talk really fast, move really fast" sort of stimulant buzz. 20mg was utterly uncomfortable. IIRC the higher doses exacerbated the positives and negatives: even better focus, even less patience, even shorter temper.
