Keep track over time
Weight-loss injections (GLP-1): what to watch
On a weight-loss injection? When a side effect starts, Hea takes your history, quotes what the product label says about it and writes a note for your prescriber or GP.
Free in the beta · Works inside the AI you already use · Last reviewed 5 November 2026
Feeling sick, constipation, tiredness: side effects are common on weight-loss injections, and it's hard to know which ones matter, or whom to tell. Hea checks the urgent signs first, takes your history and writes it down for your prescriber or GP, with sources.
How Hea helps
Urgent signs first Today
Hea asks about urgent signs before anything else. If one applies, it tells you where to go, in the NHS's own words.
What the product label says Today
Hea quotes what the US FDA product label for your medicine mentions about your symptom. A label lists many possible reactions; a symptom being listed doesn't mean the injection caused it.
A note for your prescriber or GP Today
Your symptom, when it started, what you've tried and every medicine you take go into one note, with your own questions. Blood test results you share are kept beside earlier ones of the same test.
Blood tests at home Soon
Blood tests you can do at home, kept with your earlier results.
What it looks like
Hea, I'm on a weight-loss injection — help me keep track of side effects and tests
What you’ll get
- Urgent signs checked first, with where to go in the NHS's words
- What the US FDA product label mentions about your symptom, quoted
- A note for your prescriber or GP, with your own questions
- Your blood test results beside earlier ones of the same test
- Summaries of research about these medicines in general, each with its source
Safety first
Call NHS 111 if you're using a weight-loss injection and think you might be having a serious side effect, such as severe pain in your stomach or back that does not go away.
Call 999 if your lips, mouth, throat or tongue suddenly become swollen, or you're breathing very fast or struggling to breathe.
Keep taking your medicine unless you're advised to stop. Talk to your doctor if you want to stop.
Questions people ask
What are the common side effects of tirzepatide (Mounjaro) and semaglutide (Wegovy)?
The NHS pages for both list feeling or being sick, constipation, diarrhoea, feeling tired, itchy or red skin where you inject, and hair loss. Speak to a pharmacist or doctor if a side effect bothers you or doesn't go away. Keep taking the medicine unless you're advised to stop.
Does Mounjaro make you tired?
It can: the NHS lists feeling tired among its common side effects. Tiredness has many other causes too, such as poor sleep, stress or low mood. Speak to a pharmacist or doctor if it bothers you or doesn't go away.
Which side effects of a weight-loss injection need urgent help?
Call NHS 111 if you think you might be having a serious side effect. The NHS lists an inflamed pancreas among the rare serious ones: it can cause severe pain in your stomach or back that does not go away. Call 999 for signs of a severe allergic reaction, such as a swollen throat or tongue or difficulty breathing.
Does tirzepatide (Mounjaro) affect the contraceptive pill?
The NHS says to use an extra barrier method of contraception, such as condoms, a diaphragm or a cap, for 4 weeks after starting it and for 4 weeks after each dose increase. Ask your prescriber or a pharmacist if you're not sure what this means for you.
Can Hea tell me if a symptom is from my injection?
No. Hea checks urgent signs first, takes your history and quotes what the US FDA product label mentions about your symptom. A label listing a symptom doesn't mean the injection caused it. Your prescriber, GP or pharmacist decides.
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Hea, I'm on a weight-loss injection — help me keep track of side effects and tests
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Sources
- NHS: Tirzepatide (medicine page), Page last reviewed 15 May 2026
- NHS: Semaglutide (medicine page), Page last reviewed 15 May 2026
- NHS: Anaphylaxis, Page last reviewed 21 June 2023