Most people experience digestive effects in the first week after starting or increasing a dose. These are temporary and respond well to eating smaller portions more often. Within one to two weeks, your body adjusts and symptoms ease.
Nausea is the most reported, along with rapid fullness, constipation, reflux and occasional diarrhoea. Headache and fatigue also appear, often because food intake drops faster than people realise and hydration lags behind.
The timing is the key detail. These effects arrive in the days following a dose increase and fade as your system adjusts. Something that starts suddenly at a steady dose, weeks into treatment, warrants a call to your clinician rather than waiting it out.
Much of it responds to how you eat: smaller portions, more frequent meals, protein at the start, and stopping when satisfied rather than when the plate is empty. Learn more in Nausea and digestion, Nutrition on GLP-1, and Dosing and titration.
The pattern
Managing them
Handling common side effects week by week
Expect the first week
The days after your first dose and after each increase are when symptoms bunch up. Knowing that in advance stops people quitting in week one.
Change how you eat
Smaller and more often, protein first, less fat and less at once. This does more for nausea than anything else available.
Hold rather than push
If a dose is not settling, holding it is standard. Almost everyone with a miserable experience went up too fast.
Report what does not fit
Anything severe, anything new at a steady dose, or anything on the red-flag list is a call rather than something to wait out.
Often overlooked
The less obvious effects worth mentioning
Constipation is frequently under-reported and easily managed once discussed. Dehydration is another: when appetite drops and thirst does too, fluid intake falls, which explains many of the headaches and fatigue people attribute to the medication itself.
Food aversion, where foods you previously enjoyed become unappealing, is common and usually temporary. It matters because it affects what you can realistically eat, so it is worth raising at your appointment. For more detail, see Serious side effects, Protein and muscle loss, and First month expectations.
ConstipationUnder-reported
DehydrationEasy to miss
Food aversionUsually settles
Side effects
Other side effect topics
Nausea in detail, the red flags, interactions and mood.
How long they last, whether they mean it is working, and when to worry.
Usually one to two weeks after starting or after a dose increase, then they ease. If something is not easing after that, the dose is generally the thing to adjust rather than a symptom to endure.
Not reliably. Plenty of people lose weight with very little nausea, and plenty feel unwell without much effect. They are separate things, so severity is not a progress measure.
Eating less at once and more often, protein first, and cutting back on fatty or very large meals. Most people find that does more than anything else available to them.
Report it rather than stopping unilaterally. Most of the time holding the dose fixes it. The exception is the red-flag list, where stopping and seeking care the same day is correct.
Often mildly, for a few days after each step. That is expected and is why the schedule spaces increases out rather than moving quickly.
