Does lack of water cause medicine to build up in the bloodstream?

Question

I am currently taking 200 mg a day of Lamictal, a medicine used to treat both seizure and bipolar disorders. I was wondering if it can build up in the bloodstream to a point of toxicity if you don't drink enough water. This question also goes for any medication.

Answer 1

Not really, but you're close. You're just looking at it from the wrong perspective. Taking the medicine is what causes it to build up in your bloodstream. Drinking water flushes out your bloodstream. Not drinking enough water means the medicine will not be flushed out of your bloodstream.
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Answer 2

If you are dehydrated, your body will be much more strongly affected from whatever medication you are on. You need to drink fluids, especially water in good quantities to hydrate your body.