Is a GLP-1 injection something you buy after a questionnaire?

You have seen a weekly pen, a friend has started one, or a form has offered a GLP-1 injection without anyone measuring you. The first question is usually the same: is a GLP-1 injection something you buy after a questionnaire, or a medicine a doctor may prescribe after seeing you? It is the second of those, even though a form can make the first version look like shopping.

At Medical Express Clinic the medicine under discussion is a prescription-only GLP-1 treatment, usually Mounjaro (tirzepatide). A GMC-registered doctor examines you in person on Harley Street, reviews baseline blood tests and a body composition scan, then decides whether treatment is appropriate. Meeting a number on a calculator does not complete that decision.

Is a questionnaire an examination?

The General Pharmaceutical Council, which regulates pharmacies in Great Britain, has been plain about weight-management medicines. They should not be prescribed from an online questionnaire alone. The prescriber should independently verify weight, height and body mass index before any supply is judged safe.

That safeguard exists because a form cannot examine you, take blood, or check whether the numbers you typed match the person in the room. Independent verification is the floor, not a flourish.

NICE guidance on obesity, including NG246 on overweight and obesity management (2025), treats overweight and obesity as clinical problems that need proper assessment. NICE has also appraised tirzepatide for managing overweight and obesity in defined NHS circumstances in TA1026. Those commissioning rules are not a private-clinic promise.

Licensed UK product information for Mounjaro describes tirzepatide as a prescription-only medicine given once a week under the skin, alongside a reduced-calorie diet and more physical activity, when a doctor judges it suitable. The summary of product characteristics sets out who may be treated, who should not, and which effects to watch for. It is not a shopping list.

Who may be considered?

This clinic may consider adults aged 18 to 75. Doctors may look at Mounjaro where body mass index is 30 or above, or 27 or above with a weight-related condition such as type 2 diabetes, high blood pressure or high cholesterol. Those figures sit close to the licensed adult weight-management indication, not to a guarantee.

Meeting a BMI threshold does not mean treatment will be offered. Your doctor also reviews your history, the examination, blood results, current medicines, and whether you can attend the planned reviews. BMI is a practical screen, not a complete account of health.

The body composition scan measures fat, including visceral fat, and muscle, rather than guessing from clothing size. Blood results can show diabetes risk, liver strain, kidney function or a lipid pattern that changes the decision.

What does the first visit involve?

The visit is a consultation and an examination.

Appointments run Monday to Friday at 117a Harley Street. Allow about 45 minutes for the first visit. Bring a list of medicines and any recent results you already hold.

The doctor takes a history, examines you, and reviews current medicines before deciding whether a prescription-only GLP-1 medicine is appropriate.

The included blood panel looks at full blood count, kidney function, liver function, lipids and HbA1c. Those results help the doctor decide whether treatment can be considered safely, and they sometimes point to another problem that needs attention first. A body composition scan records a starting point so later reviews can look at how your body has changed, not only the number on the scales.

A prescription is issued only when a doctor has seen you, reviewed that material, and decided the medicine is appropriate. It is never guaranteed.

When is this medicine not the right fit?

The clinic does not start Mounjaro in type 1 diabetes, because that sits outside the weight-management licence, and it does not prescribe it in pregnancy. Licensed UK information is clear that tirzepatide should not be used in pregnancy, and that it should be stopped at least one month before trying to conceive.

If you take the contraceptive pill, Mounjaro (tirzepatide) can make it less reliable. Use a non-oral method, or add condoms, for 4 weeks after starting and for 4 weeks after each dose increase. Do not use these medicines if you are pregnant, trying to conceive or breastfeeding; your doctor can discuss the alternatives. Treatment is not started if you have a known allergy to the ingredients.

Always tell your doctor about pancreatic disease, a severe gut problem such as gastroparesis, and heart, kidney, liver, gallbladder or thyroid conditions. Your doctor reviews those individually and may still decide against treatment after seeing you. Hiding a history to stay eligible is how people end up with a medicine they should not have been given.

New, severe or rapidly worsening illness needs a same-day GP or emergency assessment, not this programme. This service does not replace urgent care.

What happens if treatment starts?

If a GLP-1 weight-loss treatment is offered, you still have the same doctor at the later reviews.

The usual licensed approach is to begin at a low weekly dose and increase it gradually if you tolerate it. Your doctor sets that schedule.

The same doctor reviews you at weeks 4, 8, 12 and 16. Those visits include diet and lifestyle support, a check on side effects, and a decision on whether to adjust the dose, continue or stop. You also have direct access to your doctor between appointments.

Pens are bought separately at a pharmacy if a prescription is issued. How long anyone stays on an injection is an individual clinical decision, not a package length.

Which effects should you take seriously?

Common effects include nausea, vomiting, diarrhoea, constipation and abdominal pain. They are often milder after the early weeks, but they are not trivial. Tell your doctor if they persist or make it hard to eat and drink, so the dose or treatment can be changed if needed.

Gastrointestinal effects can lead to dehydration, which can strain the kidneys. Seek urgent medical help for severe, persistent abdominal pain, because licensed information warns about pancreatitis and tells people to stop the medicine and get help if that pain appears.

People with diabetes who also take insulin or a sulphonylurea can develop low blood sugar. If that is your situation, say so at the first visit, because doses of those other medicines may need to change.

What can the results mean?

Trial averages for tirzepatide are population figures. They do not tell your doctor how much weight you will lose, or whether you will lose weight at all.

Response depends on starting weight, how well you tolerate the medicine, other conditions, and what you can sustain with food and activity. Licensed studies showed clinically meaningful weight reduction in the groups they enrolled, alongside diet and activity, which is not a personal forecast.

Your doctor reviews progress at the four included appointments and can stop treatment if it is not tolerated or no longer appropriate. Duration is a clinical decision, not a fixed course. Suitability includes the option of not starting.

What helps beforehand?

Treat the first visit as an assessment, not a collection slot.

• Write down your medicines, including inhalers, contraceptives and anything bought without a prescription, because delayed gastric emptying can change how some oral medicines behave.
• If you use insulin or a sulphonylurea, bring the doses you take now rather than the ones on an old letter.
• Wear clothes you can be examined in, and be ready for height and weight to be measured in the clinic rather than copied from a form.
• Put the review dates in your diary before you leave, because weeks 4, 8, 12 and 16 are part of the care, not optional extras.
• Tell the doctor if you are planning a pregnancy, could be pregnant, or are breastfeeding, even if that feels awkward.
• Tell them about pancreatitis, gallbladder trouble, thyroid disease, kidney or liver problems, and any severe gut delay.
• If side effects start, contact the same doctor rather than waiting while you stop eating.

What should you avoid?

Do not treat a questionnaire as a shop.

• A GLP-1 injection is a prescription-only medicine a doctor may issue after seeing you, not an item you buy because a form said yes.
• Do not hide type 1 diabetes, pregnancy, a planned pregnancy, or an allergy in the hope of staying eligible.
• Do not start because a trial average looked attractive.
• Those figures are not a promise for you.
• Do not ignore severe, persistent abdominal pain, and do not assume nausea is always harmless if you cannot keep fluids down.
• Do not expect a pen to replace food, sleep and activity, because the licence sits alongside those changes, not instead of them.
• Do not skip the reviews if treatment starts.
• If you want a doctor-led assessment of whether supervised weight-management treatment is appropriate, the details of the clinical package, and of pen costs if a prescription is later issued, sit on the weight-loss injections page and can change.
• You can contact the clinic on 020 7499 1991.
• Appointments are Monday to Friday at 117a Harley Street.

Related guides: choosing a doctor-led health MOT and when to see a private GP.