Side effects, week by week

Most people get some gut upset. Most of it settles. Knowing roughly when it should settle is what stops a normal bad week turning into quitting the treatment altogether.

Nausea, diarrhoea, constipation and reflux, concentrated in the weeks after each dose increase. Semaglutide is much the same: Nausea, vomiting, diarrhoea and constipation, usually worst in the first weeks and after dose increases. The pattern matters more than the list — trouble clusters in the fortnight after each dose increase and eases between them.

Roughly what to expect

1. Week 1 to 2Appetite drops, sometimes abruptly. Mild nausea is common, usually a day or two after the shot. Many people feel very little at the starter dose.
2. Week 3 to 4Often the settled stretch, right before the first increase. Constipation starts to show up around here for a lot of people.
3. After each increaseThe rough fortnight. Nausea, reflux and fatigue are commonest in the two or three days after the higher dose, then ease.
4. Month 3 onwardMost people have found a rhythm. If you are still struggling badly at this point, that is a conversation about slowing the ladder, not about pushing harder.

What usually helps

• Smaller meals, eaten slowly. Volume is the usual trigger for nausea.
• Fluids, deliberately. Appetite loss reduces drinking as well as eating, and dehydration makes everything worse.
• Protein first at each meal. Losing weight fast while eating very little protein costs you muscle.
• Fibre and movement for constipation, which is close to universal.
• Asking to stay at your current dose for another month. This is a normal request.

When to stop and call somebody

• Severe abdominal pain, especially radiating to the back, or with persistent vomiting.
• Vomiting that stops you keeping fluids down.
• Signs of dehydration — dizziness on standing, very little urine, confusion.
• Swelling of the face or throat, or difficulty breathing.
• Vision changes, or a lump or swelling in the neck.

This is general information, not medical advice, and it is not a complete list. Both drugs carry contraindications a questionnaire will not always catch. Your prescriber’s instructions take priority over anything written here; in an emergency call your local emergency number.

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