Getting an In-Between Dose From a 5mg Mounjaro Pen (October 2026)

01 · The decision

Can you get an in-between dose from a 5mg pen?

No, not safely or reliably. The Mounjaro KwikPen is set by turning the dose knob until the number in the window shows the correct dose, and the pen will not let you dial past the medicine left inside it.¹³ Each pen contains four weekly doses.¹ It is a fixed-dose device for a single strength, not a graduated syringe.

If the window will not turn to a full dose, the pen does not contain enough for one and should not be used for a partial injection.¹³ That is a deliberate safeguard, not a fault to work around.

Online posts describe counting clicks or measuring liquid to hit an odd number. The dose you receive cannot be verified by counting, so the real amount is unknown.

02 · Your options

What to do instead of splitting a dose

Talk to your prescriber about what you are trying to achieve, because the right answer depends on the reason.

• Side effects on the next step up. Your prescriber can hold your current dose for longer or step you back down within the licence.¹
• Slow progress on a lower dose. Higher is not automatically better. Many people settle at 5mg, 10mg or 15mg, and your prescriber guides the pace.¹¹
• Trying to save money. You can see the current Mounjaro pen prices and consultation.

The licensed ladder starts at 2.5mg once weekly, rises to 5mg after at least 4 weeks, and then steps up by 2.5mg at minimum 4-week intervals (7.5mg, 10mg, 12.5mg) to a maximum of 15mg.¹¹¹ That is the whole range of doses a pen is built to give you.

03 · Cost

What a licensed step costs

A 5mg pen is £218.99 at standard price and a 7.5mg pen is £279.99; the 2.5mg starter pen is £169.99. A new customer's first order is £40 less with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25). All six doses are in stock. Our page on stepping from a 5mg pen towards 7.5mg and the 2.5mg pen price guide cover the neighbouring doses.

04 · How the KwikPen works

How the KwikPen dial works

The KwikPen is set by turning the dose knob until the indicator shows your dose in the window. You confirm the dose by the number you can see, never by counting clicks.¹³ That matters because many forum posts treat clicks as units, and the pen's instructions do not support that.

Each pen contains four weekly doses, and the pen will not let you dial past the medicine left inside.¹³ In practice, this means a 5mg pen is a 5mg pen from first injection to fourth. There is no setting on it for a lower or in-between amount.

If you are puzzling over what the dial is showing, our page on how many clicks people ask about sets out why the window, not the sound, is the reference. Follow the pen's own instructions for each injection and keep the leaflet that comes in the box.

05 · Microdosing safety position

Why splitting and microdosing are not safe

Taking smaller or more spread-out doses than the pen is designed to deliver, often called microdosing, is not licensed, not supported by the pen's design and not endorsed by any UK regulator.¹ Altering doses outside the licence means unknown dosing accuracy and no safety data.

The licensed ladder already starts low at 2.5mg for tolerability, and your prescriber can hold a dose longer or step down within the licence if side effects are the concern.¹ That gives you a safe, supported way to slow things down without guessing at the amount.

06 · Using up leftover medicine

What about medicine left in a pen?

If the window will not turn to a full dose, the pen does not hold enough for one injection and should not be used for a partial dose.¹³ Do not try to top it up from another pen or draw anything out of it.

Our guides to getting the remainder out of a pen and getting medicine out of a Mounjaro pen cover what is and is not sensible.

If you think a pen has delivered the wrong amount or something looks wrong, contact the pharmacy or your prescriber rather than correcting it yourself.

07 · Easing into a higher dose

Making a dose step easier

The step from one strength to the next is at least 4 weeks apart, and it is the minimum, not a target.¹¹ Your prescriber can stay at a dose for longer if you are not ready to move on.

Early effects are usually mild nausea, altered appetite and tiredness in the first days after each injection, and they usually settle.¹ Experiences differ widely, and some people feel little until a higher dose, which is also normal.

Weight loss is gradual by design. Think in months, not days, and judge progress by trend rather than individual weigh-ins.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

For reference, in the SURMOUNT-1 trial of 2,539 adults, people 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. These are trial averages, individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity.² For someone starting at 100 kg, 15% is about 15 kg.

08 · Storage and weekly timing

Storage, pen life and injection day

Keep 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.¹³ Keep the cap on to protect the pen from light.

For unopened pens, store them in the fridge until first use and they keep until the printed expiry date. If an unopened pen has been out of the fridge, check with the pharmacy before using it.¹³

Inject once a week on the same day, at any time of day, with or without food. You can change your injection day as long as at least 3 days (72 hours) have passed since your last dose.¹ If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time. If more than 4 days have passed, skip it and take the next one on your usual day. Never take two doses within 3 days of each other.¹

09 · How ordering works

How to order the right pen

We are a GPhC-registered UK online pharmacy (registration 9012878), and our Mounjaro is supplied through official LillyDirect supply, so you receive genuine KwikPens direct from Eli Lilly's UK distribution. Ordering takes three steps.

• Free online consultation. A short health questionnaire, no charge and no obligation. You can start your free consultation at any time.
• Prescriber review. Your answers are reviewed by a GPhC-registered prescriber. Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full.
• Dispatch and delivery. Same-day dispatch when ordered by 3pm, then free next-day tracked delivery in temperature-controlled packaging. Saturday delivery is £14.99.

Ongoing monthly reviews are included, so a dose question like this one can go straight to the prescribing team. If you are planning ahead, see whether you can get a three-month supply. Existing guides on an online Mounjaro prescription and the lowest-price Mounjaro options may also help. See all weight loss treatments we offer.

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. This page is information, not a substitute for medical advice.

10 · Related dose questions

Related questions about stepping down

If your concern is that 5mg feels too much, the safest answer is a conversation, not a workaround. Our page on getting 2.5mg out of a 5mg pen explains the same principle at the lower end: a 5mg pen delivers 5mg doses. If you need the lower strength, the licensed route is a 2.5mg pen.

If you notice a new symptom after any dose change, tell your prescriber and report it through the Yellow Card scheme.¹⁹

11 · 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