A tirzepatide plan, explained from first dose to long-term results

Step 1: clinical assessment before anything else

No tirzepatide plan starts with a pen in the post. It starts with a prescriber reading your medical history. At nume, that means a free consultation reviewed the same day by a GPhC-registered Independent Prescriber, a real clinician, not an automated system, working through your answers and checking them against the clinical criteria for this medicine.

Tirzepatide is licensed in the UK for adults with a BMI of 30 or above, or 27 or above where at least one weight-related condition is present (examples include high blood pressure, type 2 diabetes, dyslipidaemia or obstructive sleep apnoea). Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance. Meeting the headline BMI figure alone does not guarantee approval; the prescriber weighs the full picture. You can find a broader summary of treatment options on the weight-loss treatments page if you want to compare routes before starting.

Once approved, identity and weight are verified. For transfer patients or dose increases, evidence of current treatment is required. This is the safeguard structure that makes the rest of the plan safe to follow.

Step 2: the dose schedule, patience is built into the design

The plan has a deliberate rhythm. Treatment opens at 2.5 mg for four weeks. That first pen exists to let your system settle, not to produce significant weight loss, the GI side effects that sometimes occur in the early weeks are far easier to manage at this level. The prescriber then typically moves doses up in 4-week steps: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and up to 15 mg if tolerated and clinically appropriate.

The pace is controlled by how you respond, not by a fixed timetable. Some people stay longer at a given dose; some reach their maintenance dose before 15 mg. Titration decisions belong with your prescriber, and at nume every repeat order is clinically re-reviewed before dispatch, there are no automatic renewals. The tirzepatide overview covers the pharmacology behind this schedule if you want the mechanism in more depth.

The NICE appraisal of tirzepatide (TA1026, published December 2024) notes that continuing treatment is reviewed if less than 5% of body weight has been lost after six months at the highest tolerated dose, a checkpoint that reflects how prescribers monitor progress throughout the plan, not just at the start. You can read the NICE recommendation for tirzepatide directly for the clinical detail.

Step 3: managing side effects as part of the plan

Side effects are not a sign something has gone wrong. They are a predictable feature of how tirzepatide works, and knowing what to expect makes them easier to handle. The most common are gastrointestinal: nausea, constipation, loose stools, reflux, burping and occasional fatigue. These are typically at their peak immediately after a dose increase and ease within one to two weeks as the body adjusts.

Practical measures help: eating smaller portions, avoiding high-fat meals around injection day, staying hydrated, and not rushing food. Protein adequacy matters too, appetite falls considerably on this plan, and making what you do eat count becomes more important than it sounds. If you want guidance on structuring your food choices around treatment, the Mounjaro weight loss plan page covers how diet and lifestyle fit alongside the dose schedule.

A less common but serious concern is pancreatitis. In January 2026 the MHRA issued a Drug Safety Update highlighting acute pancreatitis as an infrequent but potentially serious effect across GLP-1 medicines. Severe stomach pain that spreads to the back, with or without vomiting, warrants urgent medical attention. The MHRA's Yellow Card scheme is where patients can report any suspected side effects, and our aftercare team is available seven days a week for questions that don't require A&E.

Women using oral contraceptives should add a non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because tirzepatide's effect on gastric emptying can reduce pill absorption. This is detailed in NHS England's guidance on weight-management injections.

Step 4: what to expect when your treatment arrives

Order by midday Monday to Friday and, once your prescriber approves, the pen is dispatched the same day. It arrives the next working day in plain, unbranded packaging via DPD, you get a tracking notification on your phone so you know exactly when to be home. Inside the box is the KwikPen itself, pre-filled and ready to use once you have read through the Patient Information Leaflet that comes with it. The pen is kept refrigerated at 2–8°C; for the precise room-temperature storage window, the leaflet is the definitive reference. Patients who want to read the full leaflet before their order arrives can find it on the tirzepatide patient leaflet page, which covers storage, administration and safety information in detail.

For a fuller picture of how the medicine works alongside the clinical plan, the Mounjaro overview brings together the evidence, eligibility and access detail in one place. If you have questions about how the process works at nume (or want to understand what our prescribers look for) about us explains the clinical setup behind the service. You can also read about the Mounjaro plan, which sets out how each stage of treatment is structured from first consultation through to ongoing review. Those interested in how individual doses are managed at each stage of the titration schedule will find a clear breakdown on the tirzepatide levels page.

When you feel ready to take the next step, check your eligibility with a free consultation. There is no commitment until a prescriber has reviewed your information and confirmed the plan is right for you.