Questions to ask your doctor before starting Mounjaro (tirzepatide)

Before your first Mounjaro (tirzepatide) dose, ask your doctor eleven questions: whether it suits your history, what the first weeks involve, what the labels say about tests, pregnancy and side effects, and how treatment is meant to end. Bring them to your 30-minute video consultation with Dr Quek at GetLean.

Each question below comes with what the label or the published evidence says and why it matters; none replaces the doctor's own assessment.

For choosing a clinic, see how to choose a GLP-1 clinic.

For the short version (what GLP-1 is, whether it is legal here, what it costs at GetLean and how to start), see GLP-1 in Singapore.

1. Does my BMI fit what the Mounjaro label covers?

Tirzepatide is registered in Singapore for weight management on its current registrations (NDF). The weight management indication runs as an adjunct to a reduced-calorie diet and increased physical activity, in adults with an initial BMI of 30 kg/m² or above, or 27 to under 30 in the presence of at least one weight-related comorbid condition — the label names hypertension, dyslipidaemia, sleep apnoea, cardiovascular disease, prediabetes and type 2 diabetes as examples (NDF). Singapore's national obesity classification applies to the whole local adult population. It sets overweight at a BMI of 23.0 and obesity at 27.5, alongside waist-circumference action points above 90 cm in men and 80 cm in women (HPB-MOH 2016). This is a population classification, not a treatment threshold.

Why it matters: Singapore runs more than one BMI scale at the same time, all of them correct, and confusing them is the commonest error in this area. Fitting a BMI range is not the same as being suitable for treatment, which a doctor decides at the consultation. The three published Singapore BMI scales and how they relate are set out in am I eligible.

2. Is there anything that rules Mounjaro out?

Singapore's product information for Mounjaro lists one contraindication, in section 4.3: hypersensitivity to the active substance or to any of the excipients (NDF). The US prescribing information for tirzepatide adds a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2) (US prescribing information). The reason is a rodent finding: in a two-year rat study tirzepatide caused thyroid C-cell tumours, and the label states that whether it does so in humans is unknown (US prescribing information). Anyone with a personal or family history of medullary thyroid carcinoma or MEN 2 should raise it, and expect a careful conversation.

Why it matters: Singapore's public page for the product carries only sections 4.1 to 4.3, so an item missing from it is not a clearance (NDF). What the doctor asks, and what each part is for, is in The questions a doctor asks before prescribing GLP-1.

3. Which conditions call for extra care?

In the US prescribing information for tirzepatide, acute pancreatitis is a warning and precaution, not a contraindication (prescribing information). In the US labels the same section also covers gallbladder disease, acute kidney injury from fluid loss, severe gastrointestinal reactions, hypoglycaemia when combined with insulin or a sulfonylurea, and diabetic retinopathy complications in people with type 2 diabetes.

Why it matters: If a procedure is planned, tell the team early. Stopping Mounjaro before surgery or a scope sets out what the current guidance says.

4. Which checks come before the first dose?

No product label in the United States, the European Union or Singapore requires a blood test before starting GLP-1 medication for weight management. The only laboratory instructions in the US labels are conditional and narrow, and Singapore's public formulary does not publish a monitoring section at all. What tests a particular doctor orders is a clinical judgement about the person in front of them, which is a separate question from what a label requires. We do not do blood tests, and we do not order them.

Why it matters: Ask which document requires it. Blood tests and GLP-1 sets out what each label does and does not require.

5. Which other medicines should the doctor know about?

Everything, including the parts people leave off: prescriptions from other doctors, anything bought over the counter, and anything a specialist started years ago and nobody has reviewed since. The US label says the medicine delays gastric emptying, which has the potential to affect the absorption of oral medicines taken at the same time (US prescribing information).

Why it matters: A slower stomach changes the timing of absorption for a swallowed medicine more or less regardless of what that medicine is, so the question is not "does this drug react with a GLP-1" but "which of my medicines depends on being absorbed predictably".

6. What if I am planning a pregnancy, or use the pill?

If you are planning a pregnancy, the stopping window is counted in months rather than days — and it differs by medicine and by which regulator's document you read. For tirzepatide, the EU document instructs at least one month, while the current US weight-management document says only to discontinue when a pregnancy is recognised and gives no pre-conception window (product information). The US and EU report near-identical pharmacokinetics and then tell patients to do different things. The US prescribing information advises patients using oral hormonal contraceptives to switch to a non-oral method, or add a barrier method, for four weeks after starting tirzepatide and four weeks after each dose increase (US prescribing information). If you take an oral contraceptive, say so at your consultation.

Why it matters: The washout is measured in months, not days. GLP-1 and pregnancy sets out both documents.

7. What is the starting dose, and how does it go up?

Singapore's product information for Mounjaro gives the starting dose of tirzepatide as 2.5 mg once weekly, increased to 5 mg once weekly after 4 weeks; if needed, further increases can be made in 2.5 mg increments after a minimum of 4 weeks on the current dose (NDF). The same page gives the recommended maintenance doses for adults as 5 mg, 10 mg and 15 mg, with a maximum of 15 mg once weekly (NDF). The US label for the weight-management product adds that the 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage (US prescribing information). Can you stay on the lowest dose of Mounjaro (2.5 mg)? covers whether a person can stay on the lowest dose.

Why it matters: Because gastrointestinal reactions cluster at the increases. Every part of this is your prescriber's decision: never raise, hold, lower or skip a dose on your own, and take a schedule from the person who wrote your prescription rather than from an article.

8. Which side effects come first, and who do I call?

The most common side effects of GLP-1 medication are gastrointestinal — nausea, diarrhoea, vomiting, and constipation — and for most people they are mild to moderate and concentrated during the period when the dose is increasing. Tirzepatide's prescribing information states the majority of nausea, vomiting and diarrhoea events occurred during dose escalation and decreased over time (prescribing information). The US Medication Guide for tirzepatide says to stop using the medicine and call a healthcare provider right away for severe pain in the stomach area that will not go away, with or without nausea or vomiting, and notes the pain may be felt from the abdomen through to the back (Medication Guide).

Why it matters: The distinction that matters is persistence and severity, not presence. The full lists are in red flags on GLP-1 and your first GLP-1 injection. If something worries you and it is not on either list, that is still a reason to contact the person who prescribed it. What to ask a clinic about reaching someone between visits is in how to choose a GLP-1 clinic.

9. What about eating, and keeping muscle?

The evidence-based range during active weight loss is approximately 1.2–1.6 g of protein per kg of body weight per day (Leidy 2015). The range exists because individual needs differ: age, activity level, how much muscle you are carrying, and how fast you are losing weight all shift the ideal number. Pick dishes where the protein is a separate object. Ask for less rice, not less meat.

Why it matters: In the SURMOUNT-1 body-composition sub-study, roughly 25% of the weight lost was lean mass and 75% was fat — in the tirzepatide arm and the placebo arm alike (Look 2025). Individual results vary, and clinical-trial figures describe the populations studied. Singapore food is covered in hawker centre when you can finish only half a plate and protein with no appetite.

10. What about alcohol, travel, fasting and festive meals?

There is no general prohibition in the product information, and there is also no evidence base saying a particular amount is fine on this medication. Given that, the sensible position is the one you would take anyway, with two additions: raise your actual drinking honestly at your consultation, and raise it specifically if you have any history of pancreatitis, gallbladder disease, liver problems, or if you take insulin or a sulfonylurea. Ask your pharmacist, and read the storage section of your own leaflet before you pack.

Why it matters: Absence of a label warning is not a clinical clearance. More on alcohol, flying with a pen, Ramadan and Hari Raya and Chinese New Year.

11. Is there a set length of treatment?

No. The length follows the goal, the response and the plan for coming off, not a number of months.

Why it matters: Individual results vary, and clinical-trial figures describe the populations studied. Never stop or change a prescribed medication on your own; how long to stay on it is a decision to make with the doctor who prescribed it. How the length is set is in how long to stay on GLP-1 medication.

What should I avoid while taking Mounjaro?

The US prescribing information for Mounjaro's active ingredient, tirzepatide, lists no food or drink to avoid. What the label says to avoid is using it with another tirzepatide or GLP-1 medicine, sharing a pen with anyone, and relying on the oral contraceptive pill alone for four weeks after the first dose and after each dose increase.

• Other GLP-1 medicines. Using it with other tirzepatide products or any GLP-1 receptor agonist is not recommended (US prescribing information).
• Sharing a pen. Never share a KwikPen, even if the needle is changed (US prescribing information).
• The pill. The label advises people taking an oral hormonal contraceptive to switch to a non-oral method, or add a barrier method, for four weeks after the first dose and after each dose increase (US prescribing information).
• Dehydration. Vomiting and diarrhoea can cause fluid loss and kidney problems; the label tells patients to take precautions to avoid fluid depletion (US prescribing information).
• Low blood sugar. The risk is higher alongside insulin or a sulfonylurea; Singapore's product information says a lower dose of those may be considered (Singapore NDF).
• Unauthorised sellers. HSA has reports of hospitalisation with severe vomiting after GLP-1 medicines that came from overseas or online sellers without a prescription (HSA 2026). GLP-1 medication sold online, without a doctor's consultation and a prescription, is unsafe.

Tell the doctor about every other medicine (tirzepatide slows stomach emptying, which can change how oral medicines are absorbed), any planned surgery or sedation, and any plan for pregnancy. No food or drink warning is not a clearance: raise alcohol with the doctor, as alcohol on GLP-1 explains.

A doctor who has your full history is the one to ask what applies to you. At GetLean, daily WhatsApp coaching keeps you in touch with our care team (9am to 9pm every day, Singapore time), so anything clinical can reach Dr Quek early, not weeks later. 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. Book your consult to see whether Mounjaro is suitable for you.

Plan how it ends before it starts

Ask at the beginning, not at the end. In the withdrawal trials the weight came back when the medication was taken away, by stopping it or by switching people to placebo. A planned exit is built around that. Questions to put to the doctor:

• How will we decide whether to continue, adjust or stop, and when will that be reviewed?
• Will the dose come down in steps rather than stop overnight, and who decides each step?
• Which eating, protein and training habits need to be in place before the medication stops quieting appetite?
• What happens if weight starts to return, and can I come back to the same doctor?

Designed to end: planning a GLP-1 exit in Singapore and Coming off Mounjaro cover what a plan contains and the weeks after the last dose.

Individual circumstances vary. Whether treatment is appropriate for you is a decision for a doctor who has assessed you.

Common questions

What is the starting dose of Mounjaro?

Singapore's product information for Mounjaro gives the starting dose of tirzepatide as 2.5 mg once weekly, increased to 5 mg once weekly after 4 weeks; if needed, further increases can be made in 2.5 mg increments after a minimum of 4 weeks on the current dose (NDF). The same page gives the recommended maintenance doses for adults as 5 mg, 10 mg and 15 mg, with a maximum of 15 mg once weekly (NDF).

Can Mounjaro affect the contraceptive pill?

The US and EU report near-identical pharmacokinetics and then tell patients to do different things. The US prescribing information advises patients using oral hormonal contraceptives to switch to a non-oral method, or add a barrier method, for four weeks after starting tirzepatide and four weeks after each dose increase (US prescribing information). If you take an oral contraceptive, say so at your consultation.

Do I need a blood test before starting Mounjaro?

No product label in the United States, the European Union or Singapore requires a blood test before starting GLP-1 medication for weight management. The only laboratory instructions in the US labels are conditional and narrow, and Singapore's public formulary does not publish a monitoring section at all. What tests a particular doctor orders is a clinical judgement about the person in front of them, which is a separate question from what a label requires.

Who cannot take Mounjaro?

Singapore's product information for Mounjaro lists one contraindication, in section 4.3: hypersensitivity to the active substance or to any of the excipients (NDF). The US prescribing information for tirzepatide adds a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2) (US prescribing information).

Is there a set length of Mounjaro treatment?

No. The length follows the goal, the response and the plan for coming off, not a number of months. Individual results vary, and clinical-trial figures describe the populations studied.

When should I call the doctor about side effects?

Tirzepatide's prescribing information states the majority of nausea, vomiting and diarrhoea events occurred during dose escalation and decreased over time (prescribing information). The US Medication Guide for tirzepatide says to stop using the medicine and call a healthcare provider right away for severe pain in the stomach area that will not go away, with or without nausea or vomiting, and notes the pain may be felt from the abdomen through to the back (Medication Guide). The distinction that matters is persistence and severity, not presence.

What should I avoid while taking Mounjaro?

The US prescribing information lists no food or drink to avoid. It says not to use tirzepatide with other tirzepatide or GLP-1 medicines, never to share a pen, and to switch from the oral contraceptive pill or add a barrier method for four weeks after the first dose and after each dose increase (US prescribing information).