It actually is not only good for you, it is something I'd recommend doing everyday you consume meth.
I'd especially recommend aspirin, as it has been proven to reduce blood clots and help reduce some of the heart issues associated that stimulants can cause.
It is also neuro-protective I believe, and will reduce the damage to receptors last time I checked.
As for dehydration, drink water, make sure to get some sodium if it is a lot, but don't assume you are always thirsty, as meth easily causes dry mouth and over-stimulation of the CNS which makes you feel thirsty, but in actuality, you are just cotton mouthed.