Is there a BMI cut-off?

Japan’s licensed obesity medicines carry defined BMI thresholds under national guidelines. Off-label self-pay prescribing does not work from a single published number — it is the doctor’s clinical judgement, taking your weight, health and history together. In practice, being at a healthy weight already is a reason to be told no.

Do I need a blood test first?

Not routinely for this treatment, but the doctor may ask for one depending on your history — for example if you have diabetes, or a condition that needs checking before starting. If so it will be explained at the consultation.

Can I start at a higher dose to get results faster?

No. Doses start low and step up, and that schedule exists to reduce side effects rather than to slow you down. Starting high mostly produces nausea severe enough to make people stop altogether.

I am already on a GLP-1 at home. Can I switch to this?

Possibly, but it is a medical decision rather than an administrative one. Semaglutide and tirzepatide are not interchangeable dose-for-dose. Bring the name of what you take, the dose, and how long you have been on it.

What if the doctor says no?

Then you pay nothing — the consultation is free — and you leave knowing something useful about your own health. We would rather that than prescribe something we are not comfortable with.

Is Mounjaro Right for You? Eligibility and Who It Is Not For

2026 9/05

English

Is Mounjaro right for you: who it is not for, what to tell the doctor, and what it is not

Medically reviewed by Dr. Itsuki Nakayama, Director, Almond Clinic Tokyo | Last verified: 25 August 2026

The short version

This is a doctor’s decision, not a checklist you can pass. Nothing on this page can tell you whether Mounjaro is right for you.
There are some people it should not be used by at all — that list is short, specific, and worth reading before you book anything.
It is not a substitute for eating and moving differently. It is prescribed alongside those, not instead of them.
If you are already at a healthy weight and want to be thinner, this is not the right tool, and a responsible doctor will say so.

People usually arrive at this question having read a great deal about how well the medicine works and very little about whether they are someone it suits. This page is the second half of that: what the doctor is actually assessing, who it is not for, and what you should tell us.

Who it should not be used by

Start here, because these are absolute rather than a matter of judgement. Mounjaro should not be used by:

Anyone who is pregnant, planning a pregnancy, or breastfeeding.
Anyone with a personal or family history of medullary thyroid carcinoma, or with multiple endocrine neoplasia syndrome type 2 (MEN 2).
Anyone who has had a serious allergic reaction to tirzepatide or to any ingredient of the product.

If any of those apply to you, please do not book a consultation expecting a prescription. We would not be able to provide one, and we would rather you knew that now than after a trip across Tokyo.

Tell the doctor about these

These are not automatic refusals. They are things that change the answer, the dose, or the monitoring — and they only work if you mention them.

A history of pancreatitis, or of gallbladder disease.
Severe gastrointestinal disease, including problems with stomach emptying.
Diabetes, and any medicine you take for it. Combined with insulin or a sulfonylurea, there is a real risk of low blood sugar and doses may need adjusting.
Kidney problems, particularly if you have had episodes of dehydration.
Diabetic retinopathy.
Any history of an eating disorder. A medicine that suppresses appetite is not neutral in that context.
Oral contraceptives, and every other medicine or supplement you take — including ones you consider unimportant.

What the consultation is for

The consultation is not a formality on the way to a prescription. The doctor is deciding two separate things: whether this medicine is appropriate for you at all, and if so, at what dose and with what precautions.

Expect to be asked about your weight history and what you have already tried, your general health and any conditions you are treated for, medicines and supplements, allergies, whether you might be pregnant, and what you are hoping for. The consultation is free, and that is deliberate — nobody should feel financially committed before this conversation happens.

Sometimes the answer is no. That is not a failure of the appointment; it is the appointment working.

See prices and how the consultation works

What this medicine is not

It is not a replacement for diet and activity. It is prescribed alongside them. Muscle is lost along with fat when weight comes off quickly, and eating enough protein and staying active is part of the treatment, not an optional extra.
It is not a short course with a permanent result. Weight commonly returns after stopping. Whether and how you continue is something to discuss at the outset, not at the end.
It is not a cosmetic product. If your weight is already in a healthy range, the risks are the same and the reason for accepting them is not.
It is not the same for everyone. Response varies, side effects vary, and no honest clinic can tell you in advance what yours will be.

The status of this treatment in Japan

In Japan, Mounjaro is approved as a treatment for type 2 diabetes. Using it for weight management is off-label use, provided as self-pay (non-insured) care. It is therefore not covered by Japanese public health insurance, and it is not eligible for the national relief system for adverse drug reactions.

Japan does have medicines licensed specifically for obesity, and they are governed by national guidelines with BMI thresholds, required complications and ongoing follow-up. We explain how that fits together, and why it rarely applies to a visitor, in Mounjaro, Zepbound, Wegovy and Ozempic in Japan.

Side effects, plainly

The most common side effects are gastrointestinal: nausea, vomiting, diarrhoea, constipation, reduced appetite and abdominal discomfort. They are usually mild to moderate, are most noticeable in the first weeks and after each dose increase, and tend to ease as the body adjusts.

Rare but important: acute pancreatitis and gallbladder disease. Low blood sugar can occur when Mounjaro is used together with other glucose-lowering medicines. If you develop severe, persistent abdominal pain, stop using it and seek medical attention — that is the symptom not to wait out.

FAQ

Is there a BMI cut-off?: Japan’s licensed obesity medicines carry defined BMI thresholds under national guidelines. Off-label self-pay prescribing does not work from a single published number — it is the doctor’s clinical judgement, taking your weight, health and history together. In practice, being at a healthy weight already is a reason to be told no.
Do I need a blood test first?: Not routinely for this treatment, but the doctor may ask for one depending on your history — for example if you have diabetes, or a condition that needs checking before starting. If so it will be explained at the consultation.
Can I start at a higher dose to get results faster?: No. Doses start low and step up, and that schedule exists to reduce side effects rather than to slow you down. Starting high mostly produces nausea severe enough to make people stop altogether.
I am already on a GLP-1 at home. Can I switch to this?: Possibly, but it is a medical decision rather than an administrative one. Semaglutide and tirzepatide are not interchangeable dose-for-dose. Bring the name of what you take, the dose, and how long you have been on it.
What if the doctor says no?: Then you pay nothing — the consultation is free — and you leave knowing something useful about your own health. We would rather that than prescribe something we are not comfortable with.

This article is general information, not medical advice, and it cannot take the place of an assessment. Whether Mounjaro is appropriate for you is a decision for a doctor who has examined you and knows your history.