Week 9 is day 63: on a four-week ladder that is week 1 of dose step 3, and — at the seven-day half-life this class runs on — 9 half-lives in. Steady state is about five half-lives, so day 35 is where the concentration stops climbing on its own. Day 63 is 4 weeks past it, which means the level is no longer the variable. That distinction is most of the question: at week 1 of a step, an effect that is still accumulating is indistinguishable from one that is not resolving unless you know which side of day 35 you are on. Vomiting is the rarer and more informative of the pair. It follows the same escalation weeks as nausea, so one arriving well away from a step is pointing at something other than the ladder. Dose decisions are made under supervision, and nothing here is medical advice.
Answer first: vomiting is less common than nausea, is more strongly dose-related, and matters chiefly because of what it does to fluid and electrolyte balance.
Warning signs that convert this from a nuisance to a clinical problem: inability to keep fluids down for more than a few hours, reduced urine output, dizziness on standing, confusion, or severe abdominal pain.
Repeated vomiting is the mechanism behind most reported acute kidney injury in this class. The renal event is a volume event, not a direct toxicity.
Oral rehydration solution composition is standardised by the World Health Organization and rests on glucose-coupled sodium transport.
The renal risk here is volume, not toxicity. That is the mechanism to watch.
edited 4 Jul 2026 by pieter_maas — added the placebo-arm figures