Tracking constipation on a GLP-1 medicine

Constipation, nausea and diarrhoea are listed among the common side effects of GLP-1 medicines such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). A short diary shows your prescriber what is happening, and when.

By The family behind Stool Log · Reviewed 5 November 2026

Why a diary helps on these medicines

Constipation, diarrhoea, nausea and vomiting are among the most common side effects in the labels of these medicines.¹² They reduce your appetite and slow digestion, and both can change your bowel habits.³ In trials of tirzepatide (Zepbound), most nausea, vomiting and diarrhoea came while the dose was being raised, and eased over time.⁴

That makes timing the useful part. "I've been constipated" is hard to act on. "Since my dose went up three weeks ago I've gone twice a week, mostly type 1 and 2" gives your prescriber something to work with.

What to log

Keep it to a few things you can note in seconds:

• Each stool, with its Bristol type. The Bristol stool chart gives you the numbers. Types 1 and 2 are hard; 6 and 7 are loose.
• Days you didn't go. On a medicine that slows things down, the gaps are the story.
• Your dose and the day you take it. Note any change of dose with its date.
• Water. Being sick or having diarrhoea makes dehydration more likely, and drinking regularly lowers the risk.⁵
• Fibre and meals, roughly: a serving of vegetables, fruit, beans or whole grains, or a skipped meal.
• Symptoms: nausea, bloating, cramps, reflux, or no appetite.
• Laxatives or fibre supplements you take, with the dose.

Reading your own pattern

After two or three weeks, look for:

• How many stools a week now, compared with before you started.
• Whether hard stools cluster in the days after your dose.
• Whether the days with more water or fibre look different.
• The longest gap between stools.

You're not looking for a cause on your own. You're collecting what your prescriber will ask about.

Talking to your prescriber

Bring your weekly numbers and the dates of any dose change. Ask what they'd like you to do if constipation continues, and whether any laxative or supplement is right for you. Don't change, skip or stop doses on your own: talk to your prescriber first.³

The labels also list rare reports of a blocked bowel and severe constipation since these medicines came on the market.¹ Mention any big change in how you go.

Keeping it easy

A once-a-week injection is easy to forget to write down, and so is water. A reminder on your dose day and a quick note after each stool are enough. If you'd rather use paper, our printable stool diary has room for a week.

This article is general information, not medical advice. Talk to a doctor or nurse about your own symptoms.