GLP‑1 side effects
This collection covers symptoms described in the NHS guidance and medicine leaflets. Begin with the overview or go straight to a symptom. Each guide distinguishes what its sources say from what needs advice about your own treatment.
A place to start
Want an overview?
Compare the common side effects listed for the different medicines.
Common side effects, and when to get helpWondering about timing?
Read what the sources say about side effects easing over time.
Do side effects ease over time?Looking up stomach pain?
Find the leaflet warnings and advice routes covered in the serious stomach pain guide.
Stomach pain: when it’s serious
Find a guide
Search by medicine, symptom or question.
19 guides in side effects
Your first weeks on a GLP-1
What the leaflets say about starting: the low first dose, the side effects most likely early on, and the pen.
Checked against 10 sources on 12 October 2026
Read the guideRed, itchy or sore where you inject
How often the leaflets say reactions where you inject happen, what they look like, and the serious signs to know.
Checked against 5 sources on 12 October 2026
Read the guideCommon side effects, and when to get help
The common and serious side effects the NHS lists for semaglutide and tirzepatide, and who to contact.
Checked against 4 sources on 12 October 2026
Read the guideStomach pain: when it’s serious
What the leaflets and the NHS say severe stomach pain can be a sign of, and what they say to do about it.
Checked against 7 sources on 12 October 2026
Read the guideLow blood sugar on a GLP-1
Who the leaflets say is most at risk of low blood sugar, the warning signs they list, and what may change.
Checked against 6 sources on 12 October 2026
Read the guideEyesight changes on a GLP-1
What the leaflets say about diabetic eye disease, the very rare NAION on semaglutide, and when to contact a doctor.
Checked against 6 sources on 12 October 2026
Read the guideAllergic reactions on a GLP-1
The signs of a serious allergic reaction the NHS lists, how rare the leaflets say it is, and what they say to do.
Checked against 6 sources on 12 October 2026
Read the guideHeadaches and dizziness
Which leaflets list headaches and dizziness, how common each is, and what the NHS says about driving.
Checked against 6 sources on 12 October 2026
Read the guideTaste changes on a GLP-1
Which leaflets list a change in taste, how common it is on each, and the changed skin sensation listed beside it.
Checked against 6 sources on 12 October 2026
Read the guideHair loss on a GLP-1
Which leaflets list hair loss, how common it is, what Zepbound’s trials found, and what the NHS says to do.
Checked against 6 sources on 12 October 2026
Read the guideFeeling sick on a GLP-1
How common feeling and being sick are on each medicine, what Zepbound’s trials found, and what the leaflets say.
Checked against 6 sources on 12 October 2026
Read the guideDiarrhoea on a GLP-1
How common diarrhoea is on each medicine, what Zepbound’s trials found, and why the leaflets stress fluids.
Checked against 6 sources on 12 October 2026
Read the guideConstipation on a GLP-1
How common constipation is on each medicine, what Zepbound’s trials found, and the severe forms the sources list.
Checked against 6 sources on 12 October 2026
Read the guideHeartburn, burping and indigestion
Which leaflets list heartburn, burping and indigestion, how common they are, and what Zepbound’s trials found.
Checked against 6 sources on 12 October 2026
Read the guideBloating and wind
How common bloating and wind are on each medicine, what Zepbound’s trials found, and when it’s serious.
Checked against 6 sources on 12 October 2026
Read the guideGallstones and the gallbladder
How common gallstones are on each medicine, what Zepbound’s trials found, and the signs its label lists.
Checked against 6 sources on 12 October 2026
Read the guideFeeling tired on a GLP-1
How common tiredness is on each medicine, what Zepbound’s trials found, and when Wegovy’s leaflet says it eases.
Checked against 6 sources on 12 October 2026
Read the guideDo side effects ease over time?
Which side effects the leaflets say usually ease, what the NHS says to do meanwhile, and when to get help.
Checked against 6 sources on 12 October 2026
Read the guideDrinking enough when you feel sick
Why the leaflets warn that being sick or diarrhoea can dehydrate you, what they say to do, and when to get help.
Checked against 6 sources on 12 October 2026
Read the guide