The US Medication Guides tell patients to stop the medicine and get help right away for severe stomach pain that will not go away, or signs of a serious allergic reaction (Medication Guides). Call a doctor if vomiting or diarrhoea does not settle. In an emergency in Singapore, go to an emergency department or call 995. At GetLean, daily WhatsApp coaching keeps you in touch with the care team, so anything clinical can reach Dr Quek early. Book your consult with Dr Quek to discuss suitability.
In Singapore, tirzepatide is registered as Mounjaro, and semaglutide injection as Wegovy for weight management and as Ozempic for type 2 diabetes. Whichever medicine is prescribed, GetLean plans the exit from the first consultation. Coming off GLP-1 in Singapore: what happens and how to plan sets out how.
Medication Guide: the patient-facing section of the US prescribing information. The wording below is drawn from it. Singapore's registered product information does not publish an equivalent section publicly, so the medicine supplied to you comes with its own patient leaflet — read that too, and follow your doctor's instructions over anything here.
Stop and seek help right away
Severe abdominal pain that will not go away. This is the clearest instruction in the whole document. The Medication Guide for both medicines says: stop using the medicine and call your healthcare provider right away if you have severe pain in your stomach area that will not go away, with or without nausea and vomiting — and notes the pain may be felt from the abdomen through to the back (semaglutide, tirzepatide). That pattern is the labelled warning sign for pancreatitis.
Signs of a serious allergic reaction. Swelling of the face, lips, tongue or throat; severe rash or itching; a very rapid heartbeat; problems breathing or swallowing; fainting or dizziness. The instruction is to stop the medicine and get medical help right away (Medication Guides).
Both of those are "right away" instructions in the source document, not "mention it at your next appointment".
Contact your doctor promptly
Gallbladder symptoms. Pain in the upper abdomen, yellowing of the skin or eyes, fever, or clay-coloured stools (prescribing information). Gallbladder disease is a listed warning for both medicines.
Vomiting or diarrhoea that does not settle. This one is easy to underestimate because it starts as an ordinary side effect. The Medication Guides are explicit that diarrhoea, nausea and vomiting may cause a loss of fluids, which may cause kidney problems, and instruct patients to tell a healthcare provider right away if these do not go away (Medication Guides). Persistence is what the instruction turns on — but severe symptoms on any single day are also a reason to seek advice rather than wait.
Symptoms of low blood sugar, particularly for anyone also taking insulin or a sulfonylurea, in whom the risk is higher. Dizziness or light-headedness, sweating, shakiness, blurred vision, slurred speech, weakness, hunger, headache, irritability, confusion or drowsiness, a fast heartbeat, feeling jittery (Medication Guides).
Vision changes, for anyone with type 2 diabetes. The Medication Guides instruct telling your healthcare provider about changes in vision during treatment, and frame that instruction specifically for patients with type 2 diabetes (Medication Guides). Any sudden change in vision is worth reporting regardless.
A lump in the neck, difficulty swallowing, shortness of breath, or persistent hoarseness. These are the symptoms patients are counselled to report in connection with the thyroid warning (Medication Guides). The underlying evidence is a rodent finding whose human relevance the US prescribing information says has not been determined — this is a report-it item, not a reason for alarm.
Before any procedure
Tell any surgeon, anaesthetist, dentist or endoscopist that you take GLP-1 medication, and do it before the day.
The reason is that these medicines slow stomach emptying, and there have been reports of stomach contents remaining despite normal fasting. Guidance here changed recently and it is worth knowing which version is current: 2023 advice to withhold weekly GLP-1 medication for a week before a procedure was superseded in October 2024 by multi-society guidance stating that most patients should continue taking the medicine before elective surgery, with those at highest risk of gastrointestinal effects advised a 24-hour liquid diet beforehand or other measures (multi-society guidance 2024). Highest risk is identified as being in the dose-escalation phase, having active gastrointestinal symptoms, or being on a higher dose.
So the instruction is not "stop before surgery". It is "tell them, early, so the team can decide". Do not stop a prescribed medicine on your own for a procedure. Stopping Mounjaro or Wegovy before surgery or a scope sets out what the 2024 and 2025 guidance says and what the labels add.
What is not on this list
Two things worth saying plainly, because both circulate.
Suicidal thoughts are not a current label warning. This was investigated as a safety signal in 2023. It was removed from both medicines' US product information in February 2026, and it does not appear in the European product information (label change logs). If you encounter a site presenting it as an active warning, that site is out of date. Any change in mood is still worth telling your doctor about — that is true of any medicine, and of weight loss generally.
Ordinary nausea, constipation and reflux are not red flags. They are common, they cluster around dose increases, and they are covered in managing nausea and constipation and reflux. The distinction that matters is persistence and severity, not presence.
The practical version
Keep it simple enough to remember:
- Severe abdominal pain that will not go away, or signs of an allergic reaction — stop, seek help now.
- Jaundice, fever, clay-coloured stools, upper abdominal pain — contact your doctor promptly.
- Vomiting or diarrhoea that will not settle — contact your doctor; this is a dehydration and kidney issue.
- Any procedure with sedation or anaesthesia — tell the team in advance.
- Anything that worries you — raise it now, not at the next appointment. At GetLean, the care team is on WhatsApp from 9am to 9pm every day, Singapore time, and anything clinical goes to Dr Quek. Outside those hours an urgent symptom does not wait for a reply: go to an emergency department, or call 995 if it is an emergency.
These medicines are Prescription Only in Singapore (HSA register), and the doctor who prescribed yours is the right person to call. In an emergency, go to a hospital emergency department rather than waiting for a clinic appointment.
Individual circumstances vary, and this article is not a substitute for the product information supplied with your medicine or for your doctor's instructions.
This page covers the rest of the body. For the skin at the injection site specifically — a mark that is spreading, increasing pain, warmth or pus — see bruises, marks and lumps, which sets the short list against what is ordinary.
Read the transcript
“GLP-1 side effects: when should I contact my doctor?”
If you’re a patient at GetLean, I want you to know when to contact us and when you need urgent help straight away.
Contact your doctor if a side effect is persistent, worsening, or stopping you from eating and drinking normally. Some symptoms need urgent medical help instead of waiting for a routine reply. The distinction matters.
Nausea, vomiting, diarrhoea, and constipation can occur with this type of treatment. If you feel mildly unsettled but can drink, eat some food, and carry on with your day, make a note of what is happening and tell your prescriber. When did it start? How often is it happening? What can you keep down? Those details are more useful than simply saying, “I feel off.” Your doctor can assess whether the symptom is related to treatment and what to do next.
If vomiting or diarrhoea continues, or you cannot keep fluids down, contact a clinician promptly. Losing fluid can lead to dehydration. Do not wait until a planned follow-up to mention that you are barely drinking. If symptoms become severe or you feel seriously unwell, seek urgent medical assessment.
There are red flags I want you to recognise. Severe, ongoing pain in the upper abdomen, particularly if it goes through to the back, with or without vomiting: stop the medicine and get urgent medical help. This can be a warning sign of pancreatitis. Sudden trouble breathing, or swelling of the face, tongue, or throat, is an emergency: stop the medicine and call emergency services immediately.
If you also take medicines for diabetes, tell the doctor who prescribes your GLP-1 treatment. Some combinations can raise the risk of low blood sugar and need individual advice. Your exact medicine and health conditions matter, so keep an up-to-date list of everything you take.
For everyday side effects, please do not change your dose by yourself, and do not assume a symptom must be harmless because nausea is common. The right response depends on what you are feeling, how severe it is, and which product you were prescribed.
The practical rule is simple: keep track of manageable symptoms and tell your prescriber; contact a clinician promptly when symptoms persist or fluids are becoming a problem; stop the medicine and get urgent help for severe abdominal pain or signs of a serious allergic reaction. Your doctor can then make the treatment decision with the full picture.
Common questions
When should you stop GLP-1 medication and call a doctor?
The clearest instruction is for severe abdominal pain that will not go away, with or without nausea and vomiting, sometimes felt through to the back — stop and contact a healthcare provider right away (prescribing information). Signs of a serious allergic reaction carry the same urgency.
What are the signs of pancreatitis on GLP-1?
Severe, persistent abdominal pain that may radiate to the back, with or without nausea and vomiting. The product information instructs stopping the medicine and seeking medical attention right away (semaglutide, tirzepatide).
What are the signs of a gallbladder problem?
Pain in the upper abdomen, yellowing of the skin or eyes, fever, or clay-coloured stools — contact a healthcare provider (prescribing information).
When is vomiting or diarrhoea serious?
When it does not go away. Fluid loss can cause kidney problems, and patients are instructed to report persistent nausea, vomiting or diarrhoea right away (prescribing information).
Should I tell my surgeon or dentist I take GLP-1 medication?
Yes, in advance of any procedure involving sedation or general anaesthesia. Current multi-society guidance is that most patients should continue the medicine, with a 24-hour liquid diet or other measures for those at highest risk (2024 guidance) — but the team can only make that judgement if they know.