Why are these three hard to tell apart?
Fatigue, cycle changes and hot flashes overlap in time and in cause. Perimenopause can bring all three at once;[7] weight change and stress can shift a cycle; and the medicine itself can bring tiredness, especially if you are eating or drinking less.[1][2] A note that records when each one happens — and what happened before — is often more useful than trying to name the cause on the day.
Is fatigue a side effect?
Both the Wegovy® and Zepbound® labels list fatigue (grouped with weakness and low energy) among the adverse reactions reported more often than with placebo.[1][2] Eating less, poor sleep, dehydration and, in people with diabetes on certain medicines, low blood sugar can all add to tiredness.[1]
The labels also warn that nausea, vomiting or diarrhoea can cause dehydration and kidney problems.[1][2]
Do GLP-1 medicines change periods?
The current US labels for Wegovy®, Ozempic®, Zepbound® and Mounjaro® do not list menstrual changes as an adverse reaction.[1][2][3][4] That does not rule out a change you notice; it means the label does not describe one.
For people using birth-control pills, the tirzepatide labels add that the pill may be less reliable for 4 weeks after starting and after each dose increase.[2] ACOG lists bleeding patterns that are not normal and should be checked.[5]
Do they cause hot flashes?
Hot flashes are not listed in these labels either.[1][2][3][4] They are a hallmark of perimenopause and menopause; the NIA describes common triggers and the options a doctor can discuss.[6] Noting time of day, sleep and what came before helps that conversation.
What does PepLabo not do?
PepLabo is a log. It does not diagnose, measure hormones or body composition, suggest a dose or tell you when to change one.
Period dates and hot flashes go in the note — there are no dedicated fields for them. Linking a check-in to a dose only stores the link; PepLabo draws no conclusions.
Wegovy® and Ozempic® are registered trademarks of Novo Nordisk A/S; Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. They are named only to identify the medicines and their labels. PepLabo has no affiliation with these companies.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Bleeding between periods or after sex, much heavier or longer periods, or any bleeding after menopause | Book a visit with your gynaecologist or doctor | At your next appointment | ACOG[5] |
| Nausea, vomiting or diarrhoea that does not go away, with dizziness or little urine | Your prescriber | Today | Wegovy® Medication Guide[1] |
| Shakiness, sweating, confusion or a fast heartbeat if you have diabetes and use glucose-lowering medicine | Your prescriber | Today | Wegovy® label §5.4, §17[1] |
| Severe stomach pain that will not go away, sometimes reaching the back | Stop the medicine and call your prescriber right away | Today | Wegovy® Medication Guide[1] |
