Practical guide
How to Dispose of a Used Mounjaro KwikPen in the UK
Once the fourth dose is gone, what do you do with the pen? The answer is simpler than most people expect, but it depends on separating the pen from the needle, and on whether the pen is finished, part-used or out of date. This guide follows the manufacturer’s instructions and UK waste rules. Needle and sharps-bin disposal has its own page, linked below.
Key facts
- The pen and the needle are disposed of separately. Remove and bin the needle in a sharps container first; the pen itself is not a sharp.
- Lilly’s Instructions for Use say a finished KwikPen with the needle removed can go in your normal household rubbish, unless your local council says otherwise. It must not go in plastics recycling.
- A pen that still contains medicine, whether part-used, unused or expired, is medicine waste and should be taken back to any pharmacy for safe destruction, not put in the bin.
- The pen contains no battery or electronics. The 2026 redesigned pen is disposed of in exactly the same way as the original.
- Never leave a needle attached to a pen, and never put a pen with a needle on it in household waste.
Step by step
- After your fourth dose, remove the needle. Put the outer needle cap back on, unscrew the needle and drop it straight into your sharps bin. See how to dispose of needles if you do not have one.
- Check the pen is finished. On the redesigned pen the plunger sits at the end of the cartridge after dose four. On the older pen a little liquid may remain; that is normal and the pen is still finished. Do not try to use it.
- Put the pen cap on and place the pen in your household rubbish, in line with the Instructions for Use, unless your council has told you to do otherwise. Some people wrap it in the box or a bag so it is not loose in the bin; that is a courtesy, not a requirement.
- Do not put it in recycling. The pen is mixed plastic with a glass cartridge and metal parts, and councils treat used medical devices as non-recyclable even when empty.
Part-used, unused or expired pens
Any pen that still holds usable medicine is different. That includes a pen you stopped using mid-way, a spare pen you no longer need because your dose changed, and any pen past its expiry date or that has been out of the fridge for more than 30 days. Take these to a pharmacy. Every community pharmacy in the UK accepts unwanted medicines for destruction free of charge, and you do not need to have bought it there. Do not flush medicine or put it in the bin: tirzepatide is a potent drug and the point of the take-back scheme is to keep it out of water and landfill.
If you are stopping treatment and have several unused pens, do not sell or give them to someone else. Supplying a prescription-only medicine to another person is an offence, and the MHRA has warned about resold and counterfeit pens circulating through social media.
Council and pharmacy variations
A few councils ask residents to put used injection pens in with clinical-waste collections rather than household rubbish, and some pharmacies will take finished pens back with unwanted medicines if you ask. Neither is the national default, so if you are unsure, check your council’s household waste page or ask the pharmacy that dispensed the pen. Scotland, Wales and Northern Ireland follow the same principle: needle in the sharps bin, empty pen in general waste unless told otherwise, medicine back to a pharmacy.
Travelling and hotels
Finished pens can go in general waste abroad as at home. Do not leave needles loose in hotel bins; carry a small travel sharps container or keep used needles in their capped state in a rigid box until you are home. Our travelling with Mounjaro guide covers storage and airport rules.
Common questions
Can I recycle the Mounjaro pen?
No. It is a mixed-material medical device and councils do not accept it in plastics recycling. Lilly does not currently run a UK pen take-back or recycling scheme.
Can I put the pen in the sharps bin?
You can, and some people do to keep things simple, but it fills the bin quickly and sharps disposal is more costly to the NHS. The needle must go in the sharps bin; the empty pen does not need to.
What about the box and leaflet?
The cardboard box and paper leaflet can be recycled as normal once you have removed anything with your name on it.
My old pen still has liquid in it. Is it really finished?
Yes. The original pen was overfilled to allow priming; the leftover is not a dose and the pen is designed for four doses only. Our golden dose guide explains why, and why the pen was redesigned in 2026.
Sources
- Medicines and Healthcare products Regulatory Agency, via the electronic medicines compendium. Mounjaro KwikPen: Instructions for Use and Patient Information Leaflet, disposal section.
- NHS. What should I do with old or unused medicines?
- Medicines and Healthcare products Regulatory Agency. GLP-1 medicines for weight loss and diabetes: what you need to know, guidance on counterfeit and resold pens.
Monj is an independent price information service operated by Medstack Ltd. It does not sell, prescribe or supply medicines and does not give medical advice. Follow the Instructions for Use in your pack and any local council guidance.
