Lowest Dose of Mounjaro for Weight Loss (October 2026)

01 · The core answer

What is the lowest dose of Mounjaro for weight loss?

The lowest dose is 2.5mg once a week. Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly. In the UK it is licensed for weight management in adults and for type 2 diabetes. It comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

Everyone starts Mounjaro on 2.5mg once a week. This starting dose is about letting your body adjust, not about weight loss itself.¹ The licensed ladder was built so that the first weeks are gentle on the stomach. It was not built to make 2.5mg a destination.

There is no lower licensed strength to move to, and no way to start below 2.5mg. If you read about people taking smaller amounts from a pen, that is not a licensed approach.

02 · Your decision

The decisions you are actually facing

After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹ Your prescriber sets the pace, and the interval is a minimum rather than a target.

03 · Next step

What to do next

If you are thinking of starting, the sensible route is a free online consultation reviewed by a GPhC-registered prescriber. They decide whether Mounjaro is suitable and which dose fits you. You can see the current Mounjaro pen prices and consultation on our product page, and our wider weight loss clinic page explains the service.

For what a typical first month feels like, see our beginner dose guide.

Honest expectations are the best preparation. The starter weeks are about getting used to the medicine. Some people notice a change in appetite straight away and others notice very little, and both are normal. Judging the medicine on the starter dose alone would be like judging a book by its first page.

04 · Why treatment starts at 2.5mg

Why treatment starts at 2.5mg

Treatment starts at 2.5mg because the body needs time to adjust to a medicine that acts on gut-hormone receptors. Tirzepatide is the first treatment of its kind to activate 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.¹ Starting on the smallest strength gives your system time to get used to those changes before the dose rises.

This is the logic behind the whole ladder. In other words, the low starting dose is a safety feature built into the licence. It is not a quirk of one provider and it is not a way of delaying the effective dose.

The dual action is also what distinguishes Mounjaro from single-action GLP-1 medicines such as semaglutide (Wegovy/Ozempic).¹ Wegovy has its own slow ladder. The principle is the same: begin low, build gradually.

It also helps to understand the pen itself. The KwikPen holds four weekly doses, so one pen of 2.5mg covers the first month of treatment. Mounjaro is injected under the skin once a week, and the pen does the measuring for you through the dose window. You do not need to calculate anything yourself, which is part of why the starter pen is straightforward to use even if you have never injected before.

What the starter dose is not is a test of whether the medicine works for you. Because the dose is deliberately gentle, a quiet first month says very little about what you will experience at 5mg and above. The patient information leaflet and your prescriber are the right places to check anything about the pen that is unclear.¹³

Starting low also gives you and your prescriber useful information. You learn how you react to the injection day, which foods sit badly, and how your appetite shifts, all at the smallest strength. That makes the next dose decision better informed. If you want to compare how other GLP-1 medicines begin, our lowest GLP-1 doses guide lines them up.

05 · The full dose ladder

The full dose ladder after 2.5mg

After the starter pen, the licensed ladder rises in 2.5mg steps to a maximum of 15mg weekly. Everyone starts Mounjaro on 2.5mg once a week. After at least 4 weeks the dose increases to 5mg, and can then step up by 2.5mg at a minimum of 4-week intervals (7.5mg, 10mg, 12.5mg) up to a maximum of 15mg weekly, depending on how you respond and tolerate it.¹

Many people settle at a maintenance dose of 5mg, 10mg or 15mg — higher is not automatically better, and your prescriber will guide the right pace.¹ The ladder is a ceiling and a route, not a schedule you must complete. If a lower dose is working and you tolerate it well, your prescriber may keep you there.

That is useful context for understanding why the early steps feel small and the later ones feel larger.

Not everyone moves up every step, and your prescriber may slow things down if side effects are troublesome.

How Wegovy's ladder compares

Wegovy follows a similar principle with different numbers. Its pens are 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg once weekly; the dose steps up after 4 weeks on each of 0.25mg, 0.5mg, 1mg and 1.7mg, so the 2.4mg maintenance dose starts from week 17. The 2.4mg dose is the licensed maintenance dose for weight management.¹⁸ The two ladders are not directly comparable by milligram, because the medicines are different.

06 · Weight loss on the starter dose

How much weight loss to expect on the lowest dose

On 2.5mg, weight loss is usually modest, and experiences differ widely. 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

The 2.5mg starting weeks are about adjustment, and experiences differ widely: some people notice appetite change and early loss in week one, others feel little until a higher dose — both are normal.¹

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 side effects are severe or do not settle, tell your prescriber rather than waiting it out.

What the trials measured

The headline trial results come from higher maintenance doses, not the starter. In the SURMOUNT-1 trial of 2,539 adults, 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 Note that 2.5mg does not appear as a result in that sentence. The trial figures describe the doses people reached after titration.

These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.² Trial averages do not predict your own result, and they should not be read as a promise for the starter dose.

Weight loss on Mounjaro is gradual by design. Trials measured results at 72 weeks — think in months, not days, and judge progress by trend, not individual weigh-ins.¹ If you want to see how that gradual shape looks over time, our page on the typical weight loss curve explains it, and our guide on whether you can lose weight on the starter strength goes deeper on the first month.

Practical advice for the starter weeks is simple. Weigh yourself on a consistent schedule rather than daily. Eat smaller, regular meals, and keep up the reduced-calorie diet and activity that the medicine is designed to support. Treat the starter month as preparation for the doses that follow.

07 · Staying on a low dose

Can you stay on the lowest dose?

Staying on 2.5mg beyond the starter period is a decision for your prescriber, not something to do alone. That is a clinical call made with you, based on how you respond and tolerate the medicine.

The licence also says that many people settle at a maintenance dose of 5mg, 10mg or 15mg. There is no licensed maintenance dose at 2.5mg, because 2.5mg is the introductory step. If you are hoping to stay on the lowest strength indefinitely to keep side effects down, speak to your prescriber about what is realistic. Our page on whether you can stay on the starter dose covers this fully.

Microdosing is not the answer

Some people ask about taking less than a full dose from a pen.

Altering doses outside the licence means unknown dosing accuracy and no safety data.¹

When a slower pace makes sense

A slower pace is a legitimate option when side effects are bothersome. Your prescriber might keep you on a strength for longer, or move down a step, and then try again later.

Review appointments are the place to talk about this. Because response is reviewed over time, you are never expected to guess the right dose on your own.

If you feel the starter dose is doing nothing, resist the urge to adjust it yourself. Mention it at your review and let the prescriber decide whether the next step is appropriate for you.

08 · Injecting and storing the starter pen

Injecting and storing your first pen

You inject Mounjaro under the skin once a week, on the same day each week, at any time of day, with or without food.¹ Licensed injection 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. Rotate the site with each dose. Each KwikPen contains four weekly doses.

There is no "best" time of day — Mounjaro works the same morning or evening, with or without food. What matters is the same day each week. Pick a day and time you will remember (many people choose a weekend morning so early side effects fall on days off) and stick to it.¹

Missed doses and changing day

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.

Storage

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 — useful for short trips — after which it should be discarded. Keep the pen cap on to protect it from light, and never use a pen that has been frozen.¹

Unopened pens should be kept 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.¹³

Needles, a sharps bin and injection guidance come with every order, so you do not need to buy anything extra before your first injection.

09 · Costs while you titrate

What the starter dose and titration cost

Your first 2.5mg pen costs £129.99 with code FIRST40, against a standard price of £169.99. You can see live prices for every strength on the Mounjaro pen page. All six doses are in stock, and each pen is four weekly doses.

New customers save £40 on their first order with code FIRST40, at any dose, including people switching to us from another provider at a higher strength. An automatic £25 reorder discount applies to every future order (code DOSE25). Every later order is £25 off the standard price.

Because the starter dose is just the first pen, it is helpful to plan beyond it. 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 any discount. A new customer's first order is £40 less and every later order £25 less.

Planning for a year

A first year of 13 pens 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, again at standard prices before discounts. If you settle at 7.5mg, 10mg or 12.5mg, the monthly standard prices are £279.99, £290.99 and £319.99. The monthly price at 5mg is £218.99 and at 15mg is £329.99.

Across the UK pharmacies we track, the cheapest and dearest 2.5mg starting pens range from £143.96 to £179.99 as of 10 October 2026. The dose you settle at drives the long-term cost, so look at that too.

Consultation is free, and the price shown is the price paid, with no hidden fees. Payment options include Visa, Mastercard, Klarna and pay-monthly options, and there are no subscriptions. Repeat orders re-check suitability, and nothing ships automatically.

10 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Get medical help straight away 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

11 · NHS access and private treatment

NHS access and private treatment

Mounjaro is available on the NHS, but access is being phased in over several years. Mounjaro must not be used during pregnancy, and it should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

The starting dose is the same either way. Whether you are treated through the NHS or privately, you begin on 2.5mg once a week, and the ladder follows the same licence. Your route only changes who prescribes and how quickly you can begin. If you want to see whether you qualify through your GP, the NHS guide is a good first step.⁵

Using a private service safely

Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary.

At EverydayMeds, the process has four steps. First, a free online consultation, which is a short health questionnaire with no charge and no obligation. Second, a prescriber review by a GPhC-registered prescriber, not a scoring script. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. Third, dispensing by our registered pharmacy, with same-day dispatch when ordered by 3pm. Fourth, free next-day tracked delivery in temperature-controlled, discreet packaging. Saturday delivery is £14.99.

We are registered with the GPhC (9012878), and we supply Mounjaro through official LillyDirect supply, direct from Eli Lilly's UK distribution. Treat any seller offering to supply without a consultation or prescription as a red flag. Genuine pens come from regulated pharmacies, and you can check a pharmacy on the public GPhC register.

Ongoing monthly reviews, dose titration and follow-up assessments are carried out by the prescribing team, with side-effect support. If you experience a side effect, you can also report it through the Yellow Card scheme. Our free GLPTrackr companion app helps you track your journey.

One more safety point matters when you stop treatment. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system — there is no way to speed this up, and nothing needs doing while it clears.¹