Mounjaro for men: what to expect week by week, from the starting dose to maintenance

Mounjaro (tirzepatide) starts at 2.5 mg once a week for 4 weeks. The dose then rises in 2.5 mg steps to a maintenance dose of 5, 10 or 15 mg. Each step comes no sooner than 4 weeks after the last. [1]

Appetite changes arrive before visible results. Side effects cluster around each dose step and ease with time. That pattern is expected.

This article sets out what the UK licence, the clinical trials and the medicines regulator say about each stage. It is a reference for men starting treatment, so you can read your own experience against what the evidence calls normal.

How does the Mounjaro dose build up?

The licence sets a minimum pace, not a target. Every patient starts on 2.5 mg once weekly.

After 4 weeks the dose rises to 5 mg. Further increases of 2.5 mg can follow after at least 4 weeks on the current dose. [1]

Stepping the dose up in stages is called titration. The table shows the schedule in the UK Summary of Product Characteristics, the licence document for the medicine. [1]

Stage	Dose	What the licence says
Weeks 1 to 4	2.5 mg once weekly	The starting dose for everyone
Week 5 onwards	5 mg once weekly	The first maintenance dose
Later steps	7.5 mg, 10 mg, 12.5 mg, 15 mg	Each increase is 2.5 mg, after at least 4 weeks on the current dose
Maintenance	5, 10 or 15 mg once weekly	The recommended maintenance doses; 15 mg is the maximum

In the weight management trials, everyone started on 2.5 mg for 4 weeks and stepped up by 2.5 mg every 4 weeks. Reaching 15 mg took 20 weeks. [1] [2]

Does everyone reach 15 mg?

No. Your clinician sets the pace from how you tolerate each step. The licence names 5, 10 and 15 mg as maintenance doses. Stopping at a lower dose is a normal outcome. [1]

The licence also sets a review point. If you have lost less than 5% of your starting weight 6 months after reaching your highest tolerated dose, your clinician reviews whether to continue. [1]

What happens in weeks 1 to 4 on the starting dose?

The first 4 weeks are about tolerability. The 2.5 mg dose is the starting dose, not a maintenance dose. [1]

Appetite can change early. In the licence's appetite study, hunger fell from week 1 of treatment and feelings of fullness rose from week 3. [1]

Side effects in the first weeks

Digestive side effects are the most common. The regulator says they are more likely at the start of treatment or after a dose increase. [4]

In the weight management trials these effects were very common. Very common means more than 1 in 10 people: [1]

• nausea
• diarrhoea
• vomiting
• constipation
• abdominal pain

Fatigue was common. The term covers tiredness and lethargy. Common means between 1 in 100 and 1 in 10 people. [1]

Injection-site reactions were also common. Redness and itching were the usual signs. In the trials, 91% of these reactions were mild. [1]

Most digestive effects were mild or moderate. [1] They can still cause dehydration. Drink plenty of fluids throughout treatment. [4]

What changes in weeks 5 to 8 at 5 mg?

At week 5 the dose moves to 5 mg, the first maintenance dose. [1] If your appetite has changed by now, the licence describes why.

This is not willpower. Tirzepatide is a GIP and GLP-1 receptor agonist. GLP-1 (glucagon-like peptide-1) is a gut hormone involved in appetite.

GIP (glucose-dependent insulinotropic polypeptide) is a second gut hormone. A receptor agonist is a medicine that acts on the same receptors as the hormone. [1]

Both receptors are found in the areas of the brain that regulate appetite. In clinical studies, tirzepatide increased feelings of fullness, reduced hunger and reduced food cravings. [1]

Cravings for fast-food fats, sweets, carbohydrates and starches fell compared with placebo. Cravings for fruit and vegetables were the exception. [1]

Why side effects return at each step

Tirzepatide slows stomach emptying. That effect is strongest when treatment starts and diminishes over time. [1]

Nausea, vomiting and diarrhoea were more frequent during the dose escalation period and decreased over time. [1] A new dose can bring a few days of symptoms. The regulator notes these effects can persist for several days. [4]

What happens between weeks 9 and 20 as the dose rises?

If your clinician continues the escalation the dose moves through 7.5 mg, 10 mg and 12.5 mg towards 15 mg. Each step needs at least 4 weeks on the current dose. [1]

The trials report side effects by dose group against a placebo, an inactive comparison treatment. In the pooled SURMOUNT-1 and SURMOUNT-2 trials, nausea affected 24.6% to 29.0% of people on tirzepatide and 8.5% on placebo. Diarrhoea affected 18.7% to 22.5% against 7.8%. [1]

Between 1.9% and 4.3% of people on tirzepatide stopped treatment because of a digestive side effect. On placebo the figure was 0.5%. [1]

Less common effects to know about

• Gallbladder problems affected 2.0% of people on tirzepatide and 1.6% on placebo. They were more likely with larger weight loss. [1]
• Hair loss was reported by 4.9% on tirzepatide and 1.0% on placebo. Most cases were mild and most people recovered while still on treatment. [1]
• Heart rate rose by a mean of 3 beats per minute. [1]
• Acute pancreatitis was uncommon, which means between 1 in 1,000 and 1 in 100 people. It is serious. The warning signs are in the section on contacting your clinician. [1]

What about the scales?

The licence says weight loss occurred early and continued throughout the 72-week trial. [1] The figures cited here are the 72-week results, so this article gives no week-by-week weight curve.

What does maintenance look like after week 20?

Once you reach a dose that is effective and tolerated, the focus shifts from escalation to consistency. The recommended maintenance doses are 5, 10 and 15 mg once weekly. [1]

SURMOUNT-1 followed 2,539 adults with obesity or overweight and no diabetes for 72 weeks. [2] The licence reports the results as if everyone had stayed on treatment for the full 72 weeks. [1]

• Mean weight loss: 16.0% on 5 mg, 21.4% on 10 mg, 22.5% on 15 mg, and 2.4% on placebo. [1] [3]
• Lost 5% or more: 89%, 96% and 96% across the three doses, against 28% on placebo. [1]
• Waist circumference fell by 14.6 cm to 19.9 cm, against 3.4 cm on placebo. [1]

Average trial results are not a prediction of individual results.

Across three weight management trials, blood pressure fell by a mean of 7 mmHg systolic and 4 mmHg diastolic. [1] Blood pressure is measured with a cuff, not a blood test.

The 6-month review

Maintenance still has a review point. The licence's 6-month review applies here.

NICE, the National Institute for Health and Care Excellence, recommends the same rule for NHS patients. If you have lost less than 5% of your starting weight after 6 months on the highest tolerated dose, your clinician decides whether to continue. [1] [7]

What if you miss a dose?

Take the missed dose as soon as possible if 4 days or fewer have passed. If more than 4 days have passed, skip it and take the next dose on your usual day. [1]

You can change your injection day if needed. Keep at least 3 days between two doses. [1]

You can take the dose at any time of day, with or without food. Rotate the injection site each dose between the abdomen and thigh, or the back of the upper arm if someone else injects for you. [1]

When should you contact your clinician?

Some symptoms need prompt contact rather than waiting for a scheduled check-in. Seek urgent medical attention for severe, persistent abdominal pain that may spread to your back. This can be a sign of acute pancreatitis. [5]

Contact your clinician promptly for:

• vomiting or diarrhoea that stops you keeping fluids down, because dehydration can harm the kidneys [1]
• signs of low blood sugar, if you have type 2 diabetes and also take insulin or a sulfonylurea [1]
• any planned operation or procedure under general anaesthetic or deep sedation, so the team knows you take tirzepatide [1]
• any new or unusual symptom that worries you

Only use medicine from a registered prescriber and an authorised pharmacy. The regulator reports counterfeit pens, some containing insulin. [4] [6]

How does HeMed fit in?

HeMed starts with a blood test. We measure 10 metabolic markers across four systems from a needle-free blood test at home.

A clinician reviews your blood test first. If they approve treatment, we deliver it the next working day, discreetly packaged, with delivery included in your plan.

A weekly in-app check-in, reviewed by clinicians, so your plan can be adjusted when it needs to be. A retest every 6 months shows what’s actually changing.

Mounjaro is a prescription medicine for weight management. Whether it’s right for you is a clinical decision, made from your health information and your baseline blood test.

Frequently asked questions

When do appetite changes start?

Appetite changes come first. In the licence's appetite study, hunger fell from week 1 and fullness rose from week 3.

Weight loss in the main trial began early and continued through 72 weeks. The published results are the 72-week figures, so this article does not give a week-by-week weight curve.

When do Mounjaro side effects settle?

Digestive side effects were most frequent during dose escalation and decreased over time in the trials. They can persist for several days after a dose change. The sources say they decrease, not that they disappear for everyone.

Is the 2.5 mg starting dose meant to cause weight loss?

The licence names 2.5 mg as the starting dose and 5, 10 and 15 mg as the maintenance doses. It sets no weight-loss target for the starting dose.

Does everyone go up to 15 mg?

No. The maintenance doses are 5, 10 or 15 mg. Your clinician decides which one suits you from how you respond and tolerate each step. The licence requires at least 4 weeks on a dose before any increase.

Does Mounjaro make you tired?

Fatigue is a common side effect in the weight management trials. The term covers tiredness and lethargy, and common means between 1 in 100 and 1 in 10 people.

No primary source shows that the medicine improves energy. If fatigue is persistent or severe, tell your clinician.

What if I miss a dose?

Take it within 4 days of the missed dose. If more than 4 days have passed, skip it and take the next dose on your usual day.

Do not take an extra dose to make up for it. If you are unsure, contact your clinician.

What does NICE recommend for NHS access?

NHS access is narrower than the licence. NICE recommends tirzepatide for adults with a BMI of at least 35 and at least one weight-related condition. BMI is body mass index, your weight against your height.

The NHS is introducing it in phases, starting with a BMI of 40 or more and four or more of the listed conditions. Private prescribing is bound by the licence criteria and is still a clinical decision.

HeMed provides clinician-led weight management. Treatment is prescription-only and is prescribed only where a clinician decides it is suitable. This page is general health information, not medical advice. If you are worried about symptoms, speak to your GP, or use NHS 111.

Next step: see what the HeMed blood test measures.

Sources (7)

1. Eli Lilly, Mounjaro KwikPen (tirzepatide) Summary of Product Characteristics, sections 4.1, 4.2, 4.4, 4.8 and 5.1 (text revised 29 August 2026). electronic medicines compendium. medicines.org.uk/emc/product/15484/smpc. Accessed 12 October 2026.
2. Jastreboff AM and colleagues. "Tirzepatide Once Weekly for the Treatment of Obesity" (SURMOUNT-1). New England Journal of Medicine 2022;387(3):205 to 216. doi.org/10.1056/NEJMoa2206038. Accessed 12 October 2026.
3. MHRA, "MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss", 8 November 2023. gov.uk/government/news. Accessed 12 October 2026.
4. MHRA Drug Safety Update, "GLP-1 receptor agonists: reminder of the potential side effects and to be aware of the potential for misuse", 24 October 2024. gov.uk/drug-safety-update. Accessed 12 October 2026.
5. MHRA Drug Safety Update, "GLP-1 receptor agonists and dual GLP-1/GIP receptor agonists: strengthened warnings on acute pancreatitis, including necrotising and fatal cases", 29 January 2026. gov.uk/drug-safety-update. Accessed 12 October 2026.
6. MHRA, "GLP-1 medicines for weight loss and diabetes: what you need to know", updated 5 February 2026. gov.uk/government/publications. Accessed 12 October 2026.
7. NICE, "Tirzepatide for managing overweight and obesity", technology appraisal guidance TA1026, 23 December 2024 (updated 1 September 2025), recommendations 1.1 and 1.2 and the implementation chapter. nice.org.uk/guidance/ta1026. Accessed 12 October 2026.

Numbered markers in the page text link to these entries. Statistics describe populations, not any one person’s results.