Should I Try Mounjaro? How to Think Through the Decision

Does your BMI and health profile put you in range?

The licensed starting point is a BMI of 30 or above. If your BMI sits between 27 and 29.9, you can still be considered if you have at least one weight-related condition, prediabetes, hypertension, raised cholesterol, obstructive sleep apnoea and osteoarthritis are among those that count. For some ethnic backgrounds, UK guidance lowers the relevant threshold by 2.5 kg/m², so South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds may qualify at a lower figure than the headline number suggests.

BMI is a starting point, not the whole picture. A prescriber also looks at your medical history, current medications, kidney function and any contraindications, a history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, for instance, rules it out entirely. You can get a rough sense of where you stand using the NHS BMI calculator before booking a consultation. Our Mounjaro overview page covers eligibility in more detail if you want to read further.

The honest version: hitting the BMI number is necessary but not sufficient. A lot of people who are in range on paper turn out to have straightforward applications; some need more discussion. That's what the clinical review is for.

What have you already tried, and how did it go?

Mounjaro is licensed as an adjunct to a reduced-calorie diet and increased physical activity, not a replacement for them. Prescribers will want to understand your background: previous diet attempts, any other weight-management medicines, bariatric surgery history. This isn't a gatekeeping exercise; it's genuinely relevant to how tirzepatide will work for you and whether the timing makes clinical sense.

If you've tried other approaches and hit a wall (whether because of how your body responds to calorie restriction, how hunger rebounds after weight loss, or a health condition that makes exercise difficult) that context matters. The mechanism here is different from a traditional diet: tirzepatide slows gastric emptying and reduces appetite signals through two pathways, which for many people changes the subjective experience of eating in ways that calorie counting alone doesn't. If you're weighing this against other options, the weight-loss treatment overview sets out what's currently available.

One practical thought: if you're considering starting Mounjaro and wondering whether now is the right time, timing can matter more than people expect. A lot of people think about this around January, or after a holiday, or when payday lands. There's no wrong month, but starting when your routine is reasonably stable tends to make the initial adjustment easier.

Are the side effects something you can plan around?

The most common side effects are gastrointestinal: nausea, vomiting, diarrhoea, constipation and indigestion feature in the trial data and are reflected in the NHS's patient information for tirzepatide. For most people they're most pronounced in the first few weeks and after each dose increase, then settle. They're real, though, and worth thinking about in advance, not to be alarmed, but so you're not caught off guard.

Serious side effects are less common but exist. Acute pancreatitis is a known risk: the MHRA issued a Drug Safety Update on GLP-1 medicines in January 2026 specifically flagging severe or persistent stomach pain that radiates to the back as a symptom requiring urgent medical attention. Gallbladder problems, significant dehydration from persistent vomiting or diarrhoea, and allergic reactions are also listed. The full picture is in the Patient Information Leaflet, which any reputable pharmacy will provide with your prescription.

Mounjaro is not recommended during pregnancy, while breastfeeding, or if you're actively trying to conceive. It's not licensed for under-18s. Women taking oral contraceptives should think carefully about whether Mounjaro is suitable for them and discuss this with their prescriber too, since tirzepatide can reduce absorption of the pill during the first four weeks of treatment and after each dose increase.

Private or NHS, what's realistic for your situation?

NHS access to Mounjaro is real but still limited. NICE recommended tirzepatide (TA1026) in December 2024, and phased rollout through primary care began in 2025, but the current criteria are strict, and not all GP practices are participating. If you're curious about whether you might qualify, the NICE appraisal of tirzepatide sets out the thresholds clearly. Many people who meet the licensed criteria don't yet meet the NHS commissioning thresholds, or simply don't want to wait.

Private prescribing fills that gap for a lot of people. If you're thinking about going on Mounjaro privately and want a clearer picture of what that involves, the most important question isn't price, it's whether the service you use has real clinical oversight and a verifiable pharmacy. Our clinical team reviews every consultation personally before any prescription is issued. You can also check whether any online pharmacy is legitimate via the GPhC pharmacy register. On the cost side, a transparent breakdown of what private treatment typically involves is on the Mounjaro pricing page.

If you'd like to work through whether Mounjaro is the right choice for your circumstances, speak to our prescribers, it's a free consultation, reviewed the same day by a real clinician.