How to Give Weekly Weight-Loss Injections: hCG and Mounjaro (October 2026)

01 · Honest answer first

If you have been given hCG injections

We do not prescribe, supply or give technique guidance for hCG for weight loss.

For any hCG product you have been given, the technique needs to come from the prescriber who supplied it and from its patient information leaflet.

If you have already been given an injectable by a clinic, follow that clinic's written instructions and ask them to demonstrate the first injection. If anything in the leaflet or from a seller conflicts with what your prescriber says, ask the prescriber before injecting.

Be cautious of sellers who offer injectables without a consultation or prescription, or who promise specific results. You can check any pharmacy on the GPhC register, and you can report a suspected side effect or a suspect product through the Yellow Card scheme.¹⁹¹²

If your real goal is weight loss, the better question is which treatments are licensed for it and how they are given. Our weight loss treatments page compares the options, and our pages on prescription-only injection routes and the clinic route explain what to ask any provider.

02 · Injection sites

Where to inject a licensed weekly weight-loss injection

Mounjaro is injected under the skin (subcutaneously), not into muscle. The licensed sites are the stomach area at least 5cm from the belly button, the front of the thigh, or the back of the upper arm if someone else gives the injection.¹¹³

Rotate the site with each dose. In practice, that means you do not use the exact same spot twice in a row. Many people alternate between the left and right side of the stomach, or between stomach and thigh.

Choose the site that is comfortable and easy to reach. Use the back of the arm only when someone else can inject you, because it is hard to do yourself.

03 · If weight loss is the goal

Is a licensed alternative right for you?

Mounjaro is licensed for weight management in adults with a BMI of 30 or above, or a BMI between 27 and 30 with at least one weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes. It must be used alongside a reduced-calorie diet and increased physical activity.¹¹¹

A prescriber assesses your BMI, medical history and current medicines before deciding whether it is suitable. Your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and all six doses are in stock. You can see current prices on the Mounjaro pen page. Every later order is £25 off the standard price.

Ordering works in three steps:

• Complete the free online consultation, a short health questionnaire with no charge and no obligation.
• A GPhC-registered prescriber reviews it. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Our registered pharmacy dispenses it, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging.

You can start your free consultation whenever you are ready. Needles, a sharps bin and injection guidance are included with every order.

Related guide: Buy hcg injections for weight loss.

04 · Step-by-step injecting

How a weekly pen injection works

A Mounjaro KwikPen is a pre-filled pen, and each pen contains four weekly doses. You inject once a week, under the skin, on the same day each week.¹

You set the dose by turning the dose knob until the correct dose shows in the window.

For the mechanics of the injection itself, such as how long to hold the pen in place, follow the pen's instructions and the patient information leaflet.

05 · Timing and missed doses

When to inject, and what to do if you miss a dose

There is no best time of day for Mounjaro. It works the same morning or evening, with or without food. What matters is the same day each week.¹

Pick a day and time you will remember. Many people choose a weekend morning so early side effects fall on days off.

If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time, then carry on with your usual day. If more than 4 days have passed, skip the missed dose entirely and take the next one on your normal day. Never take two doses within 3 days of each other.¹

You can change your weekly injection day if needed, as long as at least 3 days (72 hours) have passed since your last dose.¹

06 · Dose steps

How the dose builds up

Everyone starts Mounjaro on 2.5mg once a week. The starting dose is about letting your body adjust, not about weight loss itself.¹

After at least 4 weeks the dose increases to 5mg. It can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹¹¹

Many people settle at 5mg, 10mg or 15mg. Higher is not automatically better, and your prescriber guides the pace.

Planning the cost? If you step up after 4 weeks on each dose, your first four pens (2.5mg to 10mg) cost £959.96 at standard prices, before discounts. A first year costs £2,711.88 if you stay on 5mg after your 2.5mg starting pen, up to £3,599.88 if you step up through every dose to 15mg. A new customer's first order is £40 less, and every later order is £25 less.

07 · Storage and travel

Storing and travelling with your pen

Keep Mounjaro pens in a fridge at 2–8°C and never freeze them. Once in use, a pen can be kept out of the fridge not above 30°C for up to 30 days, after which it should be discarded.¹

Keep the cap on to protect the pen from light, and never use a pen that has been frozen.¹³

You can fly with Mounjaro. Carry pens in hand luggage, because hold luggage can fall below freezing, ideally in a cool bag with the prescription label or a copy of your prescription. For hot climates use an insulated pouch, and check destination rules for travelling with prescription injectables before you fly.¹

Unopened pens belong in the fridge and keep until the expiry date printed on the box. If an unopened pen has been out of the fridge, check with the pharmacy before using it rather than relying on a remembered day limit. Figures circulating online often come from other countries' labels.

08 · Realistic results

How much weight can you lose, and how fast?

For a licensed treatment, weight loss is gradual by design, so a 21-day figure is the wrong way to judge it. The first weeks on 2.5mg are an adjustment phase and losses are usually modest. Most measurable progress builds from 5mg onward, month by month.¹

For Mounjaro, the SURMOUNT-1 trial of 2,539 adults found that people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.²

As a worked example, for someone starting at 100 kg, 20.9% is about 21 kg. These are trial averages and individual results vary. Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

Early loss includes water weight, so the trend over weeks matters more than any single weigh-in. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects and usually settle.¹

If you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, your prescriber will discuss whether continuing or stopping is right for you.¹

09 · How Mounjaro works

How a licensed option works

Tirzepatide, the medicine in Mounjaro, activates two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹

In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly 4–5 weeks to clear the system.¹

Our page on weighing up claimed benefits explains why any treatment should be judged by its licence and trial evidence, not by marketing.

10 · NHS access

NHS access to weight-loss injections

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition.⁴

The NHS primary-care rollout began in June 2025 with the highest-need groups first, initially BMI 40+ with four or more qualifying conditions. Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.⁵⁶

Your GP can tell you whether you may qualify. If you pay privately, choose a regulated pharmacy and expect a consultation reviewed by a prescriber.

11 · Why choose regulated supply

Why regulated supply matters for any injection

Injecting is a clinical act, so where the product comes from matters as much as how you inject. We are a GPhC-registered UK online pharmacy (registration 9012878) and supply Mounjaro through official LillyDirect supply, meaning genuine KwikPens from Eli Lilly's UK distribution.

Every order follows a free consultation reviewed by a GPhC-registered prescriber, not a scoring script. Ongoing monthly reviews, dose-titration and follow-up assessments are included, along with side-effect support. Repeat orders re-check suitability, and there is no auto-shipping.

You can pay by Visa, Mastercard or Klarna, with pay-monthly options and no subscription lock-in. The free GLPTrackr app helps you log injections and track your journey. Compare options on our weight loss treatments page.

12 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹