How to track side effects on a GLP-1

The most common effects, label by label

Every US prescribing information opens with a Highlights page that names the reactions reported most often in its clinical trials. The table below collects those lists. Stomach and bowel effects head each one; depending on the product, tiredness, headache, injection site reactions or hair loss are added ^{[1][2][3][4][5][6][7][8]}.

Two cut-offs are in use. Highlights lists what was reported in at least 5% of treated people. The longer tables in section 6.1 count reactions seen in at least 2% of treated people and more often than with placebo; Table 3 of the Wegovy® label is built that way ^[2]. The rates describe groups: in the adult weight-reduction trials of Wegovy® injection, nausea was reported by 44% of people on the medicine and 16% on placebo ^[2]. They do not predict what any one person will notice.

Why the dose step belongs in every entry

Several labels tie stomach effects to the way doses are raised. Ozempic® reports that most nausea, vomiting and diarrhea came during dose escalation; Mounjaro®, Zepbound® and Foundayo™ say the same and add that these effects decreased over time; Wegovy® says its gastrointestinal reactions were reported most often while the dose was being escalated ^{[1][2][4][5][6]}. The STEP 1 trial of semaglutide described nausea and diarrhea as usually transient, mild to moderate, and easing with time ^[14].

European product information adds durations. In the semaglutide weight trials summarised in the EU Wegovy® document, the median episode lasted 8 days for nausea, 2 for vomiting and 3 for diarrhoea, while constipation ran a median of 47 days and is described as longer lasting ^[9]. A log therefore needs the day a symptom stopped as well as the day it began, plus the date of each dose change, to show whether a hard week lines up with a new strength. The article on how long side effects last goes through the timing in more detail.

What one entry should answer

Short entries are fine, as long as each one covers the same ground. These are the questions worth answering every time:

• When it started: the date, the time and how many hours or days after your last dose.
• What it was, in plain words, using the same word each time (for example always “nausea”, not “queasy” one day and “sick” the next), so entries can be counted later.
• How strong it was, on one scale you keep using: none, mild, moderate and severe, or a 0 to 10 number.
• When it ended, or a note that it is still going.
• What it stopped you doing: eating, keeping fluids down, sleeping or working.
• For a skin reaction: which injection site, and what you saw, such as redness, itching, a lump or a bruise.
• Anything else that changed: a new medicine or supplement, an illness, a dose step, a late or missed dose.
• If you also use insulin or a sulfonylurea: any signs of low blood sugar and the readings you took, since the labels link those combinations to hypoglycemia ^[1][2].

A log shows patterns, not causes

A dated record makes it easy to see that nausea returns on the second day after each injection, or that constipation began with a new strength. It cannot settle whether the medicine caused the symptom. The FDA makes the same point about its own adverse event data: an event may come from the illness being treated, from another medicine or from something unrelated, and each report reflects only what the reporter observed ^[13].

MedlinePlus separates side effects to mention if they are severe or do not go away from symptoms that need a call straight away ^[11][12]. Your clinician weighs those possibilities, and your notes give them dates and details to work with rather than a conclusion.

Fluids on a bad day

The Medication Guides link vomiting and diarrhea to fluid loss, and fluid loss to kidney problems. They say drinking fluids helps lower that chance, and they want nausea, vomiting or diarrhea that persists reported to your healthcare provider without delay ^[1][2]. The Zepbound® label asks prescribers to explain the signs of acute kidney injury and to have patients report persistent nausea, vomiting and diarrhea promptly ^[5].

In a log, that becomes three short notes on a hard day: roughly how much you managed to drink, how many times you vomited or had diarrhea, and whether you passed less urine than usual. MedlinePlus lists decreased urination among the semaglutide symptoms that need a call straight away ^[11].

Who to tell, and where reports go

Your prescriber or pharmacist is the first person to hear about a side effect that bothers you or lingers ^[2]. Each US label also prints a reporting line in its Highlights, with the manufacturer’s phone number and the FDA’s 1-800-FDA-1088 and www.fda.gov/medwatch ^[1][4]. A separate article walks through the MedWatch form and what it asks.

In the European Union, package leaflets say side effects can be reported directly through the national reporting system. The EU documents for Wegovy® and Mounjaro® carry the additional-monitoring statement, which asks for reports so that new safety information is picked up quickly ^[9][10].

Ozempic®, Wegovy®, Rybelsus® and Saxenda® are registered trademarks of Novo Nordisk A/S. Mounjaro®, Zepbound® and Trulicity® are registered trademarks and Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Novo Nordisk or Eli Lilly and Company.