Accepted answer
The relevant detail is that timing is the most useful diagnostic feature here and it is the one most often omitted from the question.
Constipation outlasts the nausea because it has two causes and only one of them resolves. Gastric emptying accommodates over weeks; total intake, and therefore stool volume and the osmotic load reaching the colon, does not recover until intake does. This is why fibre alone can make it worse — you add bulk to a system that is short of water and short of motility.
Gastrointestinal adverse events, indicative pooled rates
| Event | Active arm | Placebo arm | Timing |
|---|
| Nausea | 40–45 % | 15–20 % | Peaks 1–2 wk after each step |
| Vomiting | 15–25 % | 5–8 % | Follows nausea |
| Diarrhoea | 20–30 % | 10–15 % | Early, variable |
| Constipation | 20–25 % | 8–12 % | Later onset, persistent |
| Discontinuation for GI events | 4–7 % | 1–2 % | Mostly during escalation |
Ranges span agents and doses; read the specific prescribing information for a specific figure.
Specifically, fatigue attribution is a subtraction problem. Take out the energy deficit, the dehydration, the electrolyte shortfall and the poor sleep, and what remains attributable to the drug in the trials was modest — placebo-arm fatigue rates were within a few points of active-arm rates in most of the programme. The corollary is that the fixable causes are usually the actual causes.
SURMOUNT-1 reported gastrointestinal events as the most frequent adverse events, mostly mild to moderate and mostly during escalation, with discontinuation for adverse events in the single digits per cent[1].
I would flag that attributing a symptom to a drug is a hypothesis, and the base rate of these symptoms in the general population is high enough that the hypothesis is often wrong.
A symptom diary with dates against dose steps answers most of these questions without anyone needing to guess.
edited 12 Jan 2026 by rania_haddad — clarified the distinction between purity and content
6Is there a reason to prefer the second method over the first, other than cost? – coldbox9 5 months ago add a comment