Guide · by Dr. Priya Raman, MD · October 2026
Nausea, constipation, fatigue and reflux are common in the first weeks on semaglutide or tirzepatide and usually ease as the dose settles. Rarer problems exist and are listed here plainly. By Dr. Priya Raman, MD.
The short answer
Most side effects come from the medication slowing your stomach: nausea, feeling full early, reflux, constipation, sometimes diarrhoea, and tiredness in the first weeks after each dose increase. They are usually mild and usually ease within a few weeks at a given dose. Rarer but serious problems include pancreatitis, gallbladder disease, severe dehydration and, with some conditions, a reason not to prescribe at all. The weekly nurse check-in exists so a bad week is caught in days and the dose is held, not raised. This is general information about a class of medication, not advice for you; the Starting Line is where that happens.
| When | What you may feel | At Wrenhaven |
|---|---|---|
| Weeks 1 to 2 | Nausea, early fullness, tiredness | Lowest dose, small meals, water; nurse call on day three |
| Weeks 3 to 4 | Constipation or reflux as food slows | Fibre and fluid plan from the dietitian; dose held if needed |
| Each dose increase | A repeat of week one for a few days | Increase only after a check-in; never two increases in a row without one |
| Any week | Severe pain, vomiting you cannot stop, signs of dehydration | Call the nurse the same day; urgent care if told to |
| Week 12 | Appetite changes as the plan ends or the dose steps down | Taper on the plan, maintenance with the dietitian |
What moves it
Plainly
A clinic that sees you monthly learns about week two at week four. Ours hears about it on day three, holds the dose, adjusts the food, and tells Dana. That is the difference between a side effect and a reason to quit.
Call your nurse for anything that worries you; that is what the number is for. Do not wait on severe or persistent abdominal pain, vomiting you cannot stop, yellowing skin or eyes, or feeling faint. Those are same-day calls, and sometimes urgent care.
Author
Medical Director
Priya is a physician with a background in obesity medicine who founded Wrenhaven in 2022. She writes the protocols, reviews every plan before a prescription is written, and is in the building during clinic hours as the collaborating physician.
Most people feel queasy for a few days after a start or an increase and then settle. Persistent nausea at a dose means the dose is wrong for now, and we hold it.
Some people notice shedding a few months into any rapid weight change. It is usually temporary; protein and the dietitian help.
Losing weight quickly without enough protein and strength work costs muscle. That is why the body composition reading is repeated and the dietitian is included.
Less than before, and slowly; many people find it sits badly. We say so at the Starting Line.
The Starting Line · 75 min · $149, credited
The Starting Line is seventy-five minutes with a nurse practitioner and ends with a written plan with the price on it.