Needles for the KwikPen
The KwikPen does not come with needles. Your pharmacy or clinic supplies them, and each weekly pen needs at least four.
It takes a standard screw-on pen needle, the same kind insulin pens use, so the ordinary pen needles sold in UK pharmacies fit.
Lilly says a 4 mm needle is suitable for adults, and that you put a new needle on for each dose. Four doses, four needles, plus a spare or two.
After the jab the used needle comes off and goes in a sharps bin, the yellow box for used needles. Not the household bin, and not left on the pen.
NeedleBay holds the month's needles, fresh and used, until the sharps bin. From £14.95.
Does the KwikPen come with needles?
No. Lilly's instructions for the Mounjaro® KwikPen say "needles are not included in the pack", and the supplies list asks for a "KwikPen compatible pen needle". The pen holds four doses, one a week, and is thrown away after the fourth dose or 30 days after first use.
If you get the pen on an NHS prescription, your GP or nurse adds pen needles to the prescription and the pharmacy supplies them. Online clinics vary: some send four needles with each pen, some send a box, and some tell you to buy your own locally and claim the cost back. Check what came in your parcel before your first dose. (Clinic policies as published in October 2026.)
Either way you will usually end up with a box of 100 loose needles for four jabs a month. That is where a small case earns its keep, and we come to that below.
Which needles fit the KwikPen?
Lilly does not make needles. It says to use pen needles made to the ISO 11608-2 standard, and names Embecta (the BD brand), Novo Nordisk and Terumo as examples. In plain words, the ordinary pen needles sold in UK pharmacies fit. NHS guidance in Bristol, North Somerset and South Gloucestershire says its listed needles are "compatible with all licensed insulin and GLP-1 receptor agonist pens in the UK" and that "patients should be told brands are interchangeable".
| Pen needle | Fits the KwikPen? |
|---|---|
| BD Micro-Fine Ultra (Embecta) | Yes, Embecta lists the KwikPen |
| BD Viva (Embecta) | Yes, NHS ICB statement |
| Insupen Original | Yes, NHS ICB statement |
| Microdot Max | Yes, NHS ICB statement |
| GreenFine Neon | Yes, NHS ICB statement |
| GlucoRx CarePoint | Yes, NHS ICB statement |
| NovoFine (Novo Nordisk), Terumo | Named by Lilly as ISO 11608-2 makers; check the box |
| mylife Clickfine, Unifine Pentips | ISO pen needles; not checked by us, check the box |
The box lists the pens it fits. If it says KwikPen, or says ISO 11608-2, it fits. Sources: Lilly UK Medical needle FAQ (August 2025), Embecta compatibility list, BNSSG ICB pen needle guidance (April 2024), seen October 2026.
What size needle?
Lilly says a 4 mm needle is suitable for adults and that shorter needles are generally better tolerated, with the final choice left to your prescriber or pharmacist. The international injection-technique guidance (FITTER, 2016) recommends 4 mm for adults regardless of age or build, because skin is only 2 to 2.5 mm thick wherever you inject. 4 mm 32G is the size most often prescribed for insulin pens, and it fits the KwikPen. Some NHS areas use 4 mm or 5 mm only; online clinics send 4 mm, or 5 mm or 6 mm, and those fit too.
You may see the size written both ways: "4 mm 32G" (length first, the NHS way) and "32G x 4mm" (the way the box is often printed). Same needle.
A new needle each time
Lilly's instruction is "always attach a new compatible needle to the KwikPen before each dose", and the US leaflet for the same pen gives the reasons: a fresh needle helps prevent infections and blocked needles. The pen is also stored with the cap on and no needle attached, because a needle left on can let air in or medicine leak out.
So the count is simple: four doses, four needles, plus a spare or two in case a prime fails and the needle has to be changed. That is why needles come in boxes of 100, and why four bays, one per week, is the NeedleBay layout.
Where to buy pen needles and what they cost
On an NHS prescription in England a box is one prescription charge, £9.90 in 2026/27, or free with an exemption certificate or a prepayment certificate. The NHS itself pays about £2.50 to £3.60 per 100 for the brands in the table. Privately, a box of 100 BD Micro-Fine Ultra 4 mm was £13.46 at one UK medical supplier in October 2026, and most pharmacies sell pen needles over the counter. One online clinic refunds up to £10 if you have to buy your own.
Putting the needle on and priming
These are Lilly's own steps, not ours, and your leaflet comes first.
- Push the capped needle straight onto the pen and twist until tight.
- Pull off the outer shield and keep it. Pull off the inner shield and bin it.
- Prime: turn the dose knob two clicks to the extended line, hold the pen up and push the knob in until it stops. A drop at the tip means it is primed. If nothing appears, repeat up to two more times; if still nothing, change the needle and try once more.
- Inject, holding for a count of five.
A practical tip, ours not Lilly's: if nothing comes out, check the inner shield has actually come off. It is small, clear and easy to miss, and with it on the needle cannot reach the skin. Do not turn the knob past two clicks to prime; Lilly says that wastes medicine and can mean the pen does not give all four doses.
Where does the used needle go?
Lilly's rule: put the outer shield back on, unscrew the needle and put it in a sharps container. Loose needles must not go in household waste, and the pen must not be stored with the needle attached. The pen goes back in its box with the cap on and no needle.
Your pharmacy, GP surgery or council can tell you how to get a sharps bin and where a full one goes; it varies by area, and our pen needle storage guide has more. Between jabs, NeedleBay holds the used needle locked in its bay until you reach the bin, so nothing is loose in a drawer or a handbag. It is not a sharps bin and does not replace one.
How NeedleBay can help
Every question above ends in the same place: a box of 100 loose needles, a fresh one each week, a used one that has to go somewhere, and a weekly jab that is easy to lose track of. NeedleBay is a pocket case with four bays that deals with each of those.
A box of 100 is not a thing you carry. Four fresh needles sit ready in the case, seals on.
A new needle each dose. One bay per jab; the pen screws straight onto the needle in its bay.
Did I do this week's? One look at the lids shows whether the jab is done, which helps prevent a missed week and a double week.
The used needle. It locks back in its bay until you reach a sharps bin, so nothing is loose in a bag or a drawer. NeedleBay is not a certified sharps bin and does not replace one.
Load four new needles when you start a pen, screw the pen onto each one in turn, week by week, and screw it back into the same bay afterwards. When the pen is finished, the four used needles drop into the sharps bin together. No app, no battery. It holds the needles, not the pen.
To check which NeedleBay case holds your KwikPen needles and a month's spares, see our guide to which GLP-1 pens fit.
Quick answers
Does the KwikPen come with needles?
No. Lilly's instructions say needles are not included. Your prescriber, pharmacy or clinic supplies them, and some clinics ask you to buy your own.
Which needles fit the KwikPen?
Pen needles made to ISO 11608-2, which covers the common UK brands: BD Micro-Fine Ultra, BD Viva, Insupen, Microdot Max, GreenFine Neon and GlucoRx CarePoint among them. The box lists the pens it fits.
What size needle for the KwikPen?
Lilly says 4 mm is suitable for adults; 5 mm and 6 mm also fit and some clinics send those. The gauge is usually 31G or 32G. Your prescriber or pharmacist makes the final choice.
Can I reuse a KwikPen needle?
Lilly says a new needle before each dose. A fresh needle helps prevent infection and blocked needles.
How many needles do I need per pen?
Four, one per weekly dose, plus a spare or two in case a prime fails and the needle has to be changed. That is our arithmetic from Lilly's instructions, not a Lilly figure.
Where do I buy KwikPen needles?
On prescription from your GP or clinic, or over the counter at most pharmacies and online medical suppliers. A box of 100 is around £13 privately (October 2026), or one prescription charge on the NHS in England.
Why is nothing coming out when I prime?
Lilly says repeat the two-click prime up to two more times, then change the needle and try once more. Also check the small clear inner shield has come off the needle. If it still fails, contact Lilly or your pharmacist.
Can I leave the needle on the pen?
No. Lilly says store the pen with the cap on and no needle attached. A needle left on can let air in or medicine leak out.
What do I do with the used needle?
Outer shield back on, unscrew, into a sharps container. Not the household bin. NeedleBay holds the used needle until you reach the sharps bin; it is not a sharps bin itself.
Is the US version the same pen?
In the US the same pen is sold under a different name. Its instructions carry the same "pen needle not included" line and the same two-click prime, so what this page says about needles applies to it too. In the US, used needles go in an FDA-cleared sharps container.
What this page is not
This is a page about pen needles and a needle case. It is not medical advice, it does not cover doses, and it does not supply or link to the medicine. Your pen's leaflet and your prescriber come first.
Four weeks of needles, fresh and used, in one pocket case. From £14.95, £2.95 UK delivery, 30-day returns.
Needle facts are taken from the Mounjaro KwikPen instructions for use and Lilly UK Medical's answers, seen October 2026, and from NHS pen needle guidance. Pens and leaflets change, so follow your own leaflet and ask your pharmacist if unsure. KwikPen® and Mounjaro® are registered trade marks of Eli Lilly and Company. NeedleBay is an independent maker of pen needle cases and is not connected with, sponsored by or endorsed by Eli Lilly and Company. NeedleBay does not sell needles or medicines.