What is the difference between Mounjaro and Ozempic?

Ozempic (semaglutide) is a single-mechanism agent that acts only on the GLP-1 receptor. Mounjaro (tirzepatide), by contrast, is a dual agonist that acts on both the GIP and GLP-1 receptors, and is expected to deliver more potent glucose-lowering and weight-reduction effects.

Are the side effects of Mounjaro serious?

The most common side effects are gastrointestinal symptoms such as nausea, vomiting, and diarrhea. These typically appear early in treatment and improve within a few weeks. Serious adverse events such as pancreatitis or thyroid tumors are rare but possible, so treatment should be conducted under regular medical supervision.

Can I get Mounjaro through online medical consultation?

Yes. Our clinic offers Mounjaro prescriptions through online medical consultation. The first visit is conducted online for medical history and examination, and the medication is prescribed if appropriate. The drug is shipped to your home, so you can begin treatment without visiting the clinic in person.

How much does Mounjaro cost?

Under self-pay (out-of-pocket) care, the drug cost per pen (one weekly dose) is approximately JPY 15,000-25,000 depending on dosage. Monthly costs are typically JPY 60,000-100,000. Initial consultation and prescription fees may apply separately.

Who is Mounjaro suitable for?

Mounjaro is suitable for patients with overweight or obesity (BMI 25 or above) and for patients with type 2 diabetes whose blood glucose is not adequately controlled. However, it cannot be used in patients with a history of pancreatitis, a family history of thyroid cancer, or those who are pregnant or breastfeeding. A physician will confirm eligibility during examination.

Will my weight come back if I stop Mounjaro?

When treatment is discontinued, the appetite-suppressing effect ends and weight regain is possible. Mounjaro is intended as medical support, and combining it with improved diet and exercise habits helps reduce the risk of rebound after discontinuation.

Mounjaro (Tirzepatide) for Weight Loss: Effects, Side Effects & Cost Guide [2026]

Image of a physician consultation

“I cut back on food but my weight won’t drop.” “I exercise but I’m not seeing results.” For people facing these struggles, Mounjaro (tirzepatide) is now drawing major attention.
This new-generation obesity treatment, which has captured worldwide interest, has been reported in clinical trials to deliver weight reduction beyond that of conventional GLP-1 receptor agonists, and prescriptions at medical institutions in Japan are rapidly increasing.

In this article, we provide a physician-reviewed, easy-to-understand explanation of Mounjaro’s mechanism, effects, side effects, costs, and how it compares with other obesity treatments.
We also answer common questions such as “Is Mounjaro right for me?” and “Can I get a prescription via online consultation?”, so please read to the end.

Contents

What is Mounjaro (tirzepatide)?
How Mounjaro works and its effects
Comparison with other obesity treatments (Ozempic, Wegovy, Rybelsus)
Indications and eligibility for Mounjaro
Side effects and precautions
Administration and dosing
Costs and insurance coverage
How to get Mounjaro through online medical consultation
Frequently asked questions (FAQ)
Summary

1. What is Mounjaro (tirzepatide)?

Image of an injectable medication

Mounjaro (generic name: tirzepatide) is an injectable medication developed by US pharmaceutical company Eli Lilly and was originally approved as a treatment for type 2 diabetes.
In Japan, it was approved and launched as a type 2 diabetes treatment in September 2023. Because the same active ingredient was later approved overseas as the obesity drug “Zepbound”, it has rapidly drawn attention in the context of medical weight loss as well.

Mounjaro’s biggest distinguishing feature is that it is a dual agonist that acts on both the GIP receptor and the GLP-1 receptor.
Existing obesity drugs (Ozempic, Wegovy, etc.) act only on the GLP-1 receptor, but Mounjaro simultaneously engages GIP, delivering stronger appetite suppression, blood-glucose control, and weight-loss effects.

Note: GIP and GLP-1 are both incretin hormones secreted from the gastrointestinal tract after meals. They promote insulin secretion to lower blood glucose and act to suppress appetite. By binding to both of these hormone receptors at the same time, tirzepatide produces effects superior to single-target agents.

2. How Mounjaro works and its effects

Image representing weight management

The biggest reason Mounjaro is attracting attention is its remarkable weight-loss effect.
In the international clinical trial “SURMOUNT-1”, treatment with Mounjaro for 72 weeks (approximately 17 months) produced an average weight loss of approximately 20.9% at the highest dose (15 mg). For an 80 kg patient, this is equivalent to a reduction of about 17 kg.

Primary mechanisms of action

STEP 1
Appetite suppression: Acts on the hypothalamus to powerfully suppress appetite, leading to a natural reduction in food intake.

STEP 2
Delayed gastric emptying: Slows the movement of food from the stomach to the small intestine, prolonging the feeling of fullness.

STEP 3
Promotes insulin secretion: Increases insulin release in response to post-meal blood glucose rises, improving glucose control.

STEP 4
Improves fat metabolism: Through action on the GIP receptor, promotes fat-tissue metabolism and contributes to a reduction in visceral fat.

Estimated time to see effects

The time it takes for Mounjaro to take effect varies by individual, but a general guide is shown below.

Treatment period	Expected change
Weeks 1-4	Decreased appetite and natural reduction in food intake
Weeks 4-8	Noticeable weight loss (approximately 2-5 kg)
Months 3-6	5-10% weight reduction, improvement in blood glucose
Months 6-17	Maximum effect (average 15-20%+ weight reduction)

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3. Comparison with other obesity treatments

Below is a comparison of the main injectable medications currently used for medical weight loss.

	Mounjaro	Ozempic	Wegovy
Generic name	Tirzepatide	Semaglutide	Semaglutide
Mechanism	GIP + GLP-1 (dual)	GLP-1 only	GLP-1 only
Administration	Once-weekly subcutaneous injection	Once-weekly subcutaneous injection	Once-weekly subcutaneous injection
Average weight reduction	Approx. 15-21%	Approx. 9-14%	Approx. 15-17%
Approval in Japan	Type 2 diabetes (Sept 2023)	Type 2 diabetes (2021)	Obesity (2023)
Self-pay (monthly est.)	Approx. JPY 60,000-100,000	Approx. JPY 30,000-60,000	Approx. JPY 50,000-80,000

Key point: Mounjaro has the highest reported weight-loss effect of these three options. However, it tends to cost more, and the best choice depends on body weight, BMI, underlying conditions, and lifestyle, all of which the physician will weigh up. If you are unsure which option is right for you, please start with an online consultation.

4. Indications and eligibility for Mounjaro

The main candidates for whom Mounjaro is considered are listed below. Final eligibility, however, must always be determined by a physician’s examination and judgment.

Patients likely to be candidates for prescription

People who are overweight or obese (BMI 25 or above)
People who have difficulty losing weight through diet and exercise alone
Patients with type 2 diabetes whose blood glucose is not adequately controlled
Patients with obesity-related conditions such as hypertension, dyslipidemia, or sleep apnea
Patients who used GLP-1 receptor agonists previously but did not achieve sufficient results

Patients who cannot use Mounjaro (contraindications and cautions)

Caution: Patients in the following groups may not be able to use Mounjaro. Please be sure to inform your physician in advance.

Patients with a history of pancreatitis
Patients with a personal or family history of medullary thyroid carcinoma
Patients with type 1 diabetes
Patients with severe kidney or liver disease
Women who are pregnant or breastfeeding
Patients with hypersensitivity to any component of the medication

5. Side effects and precautions

Image of a clinic consultation

Mounjaro is highly effective, but it does have side effects. Most side effects appear early in treatment and can be reduced by gradually titrating the dose, but it is important to be aware of them in advance.

Common gastrointestinal side effects

Side effect	Frequency	Management
Nausea	Approx. 20-30%	Start at low dose, titrate up; inject after meals
Diarrhea	Approx. 15-20%	Stay hydrated; adjust diet
Constipation	Approx. 10-15%	Increase fiber intake; stay hydrated
Vomiting	Approx. 5-10%	Eat smaller meals and rest
Injection-site reaction (redness, itching)	Less than 5%	Rotate injection sites

Serious side effects (rare but require attention)

What to do: If any of the following symptoms appear, contact your physician immediately.

Acute pancreatitis: severe abdominal or back pain with fever – seek immediate care
Gallbladder disease: right upper abdominal pain, jaundice
Hypoglycemia (when combined with insulin): palpitations, sweating, tremor, decreased consciousness
Thyroid mass: a lump in the neck, hoarseness, difficulty swallowing

6. Administration and dosing

Mounjaro is self-administered as a once-weekly subcutaneous injection. It uses a dedicated pen-type auto-injector, so even patients who are new to injections can easily administer it at home.

Standard dose-escalation schedule

Weeks 1-4
2.5 mg/week (induction dose)

Weeks 5-8
5 mg/week (maintenance dose 1)

Week 9 onward
7.5 mg-15 mg/week (titrated up at the physician’s discretion)

* The pace of dose escalation varies depending on side effects, response, and weight changes. Always follow your physician’s instructions.

Recommended injection sites are the abdomen, thigh, and outer upper arm. It is important to rotate sites and avoid injecting in the exact same spot each time.
The medication must be stored refrigerated (2-8°C). Proper home storage will be explained to you when the medication is dispensed.

7. Costs and insurance coverage

Image of cost calculation on a smartphone

The cost of Mounjaro varies significantly based on the indication (diabetes treatment vs. obesity treatment) and the dose used.

Insurance-covered (type 2 diabetes treatment)

When used for type 2 diabetes treatment, Mounjaro is eligible for national health insurance (30% co-pay).
In this case, monthly out-of-pocket costs depend on the dose but are typically around JPY 3,000-8,000 (a ballpark figure including consultation and drug costs).

Self-pay (medical weight loss)

Dose	Drug cost (per pen)	Estimated monthly cost
2.5 mg / 5 mg	Approx. JPY 15,000-18,000	Approx. JPY 60,000-70,000
7.5 mg / 10 mg	Approx. JPY 20,000-23,000	Approx. JPY 80,000-90,000
12.5 mg / 15 mg	Approx. JPY 23,000-26,000	Approx. JPY 90,000-100,000

* Figures above are estimates only. Initial consultation and prescription fees may apply separately. Please confirm details at your visit.

8. How to get Mounjaro through online medical consultation

A man having an online medical consultation on his smartphone

Our clinic offers Mounjaro prescriptions through online medical consultation. You can complete everything from consultation to prescription with just a smartphone, with no clinic visit required, so even busy patients can use the service with confidence.

STEP 1
Book online
Book your consultation through our official website or LINE. Reservations are available 24/7.

STEP 2
Video consultation (about 10-15 minutes)
A physician conducts an online interview, reviewing your current weight, BMI, medical history, and current medications, then determines whether Mounjaro is appropriate for you.

STEP 3
Prescription and payment
If you are determined to be a candidate, the prescription is issued. After online payment, the medication is shipped to your home.

STEP 4
Self-administration at home and follow-up
You self-inject once a week at home. Monthly online follow-ups track your weight progression and any side effects to keep treatment safe.

9. Frequently asked questions (FAQ)

Q. How long does it take for Mounjaro to work?

A. Although individual responses vary, many patients begin to notice weight loss within 4-8 weeks of starting therapy. Clinical trials have reported an average weight loss of 15-20% or more after 72 weeks of treatment.

Q. Which is more effective: Mounjaro or Ozempic?

A. Clinical trial data show that Mounjaro produces greater weight loss. However, side-effect profiles and individual response also matter, so which is best for you is determined by a physician on a case-by-case basis.

Q. Is Mounjaro covered by insurance?

A. Insurance covers it for type 2 diabetes treatment. When used for obesity treatment (medical weight loss), it is provided as out-of-pocket (self-pay) care. Please check the details at your consultation.

Q. Will I regain weight if I stop?

A. When treatment is stopped, the appetite-suppressing effect ends and there is a risk of weight regain. Combining therapy with improvements in diet and exercise habits makes it easier to maintain results after discontinuation.

Q. Can I inject Mounjaro myself?

A. Yes. Mounjaro uses a pen-type auto-injector, so even patients with no prior injection experience can easily self-administer it at home. Instructions are provided through video and a manual at the time of prescription.

10. Summary

In this article, we provided a detailed explanation of Mounjaro (tirzepatide). Below is a summary of the key points.

Mounjaro is a dual GIP + GLP-1 receptor agonist and offers stronger weight reduction than conventional obesity treatments
Clinical trials confirmed an average weight loss of approximately 20.9% at the highest dose
Once-weekly subcutaneous injection that can be self-administered at home with a pen-type injector
Common side effects include nausea and diarrhea, but they can often be reduced by titrating up from a low dose
Insurance covers type 2 diabetes treatment; obesity treatment is self-pay (approx. JPY 60,000-100,000/month)
Our clinic offers prescription via online medical consultation, so treatment can be started without visiting the clinic

Ready to take serious control of your weight with Mounjaro?

Through physician-supervised online medical consultation, we will recommend a treatment plan tailored to you.

Start today, all from your phone.

Get a free consultation

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Reviewed by: Physicians at Shimbashi Ginza Swift Clinic (formerly Men’s Care Clinic Shimbashi).
Specialties include internal medicine, obesity treatment, and diabetes. Reviewed in accordance with Japan’s Ministry of Health, Labour and Welfare guidelines and the Japan Society for the Study of Obesity.
This article is provided for medical information only and does not guarantee diagnosis or treatment. Always consult a physician regarding treatment.