Why Is There Liquid Left in My Mounjaro Pen? (October 2026)

01 · The short answer

Is it normal to have liquid left in a Mounjaro pen?

Yes.

Our related guides cover why there can seem to be so much left and why Mounjaro remains in the pen in more detail.

02 · Next steps

What should you do with the leftover liquid?

Dispose of the finished pen in your sharps bin; sharps bins and injection guidance come with every order. Used needles go in a sharps bin, never household waste. Your local council or GP surgery can tell you how full bins are collected or returned in your area. Do not try to draw the remainder into a syringe, and do not top up a dose from it. Each Mounjaro KwikPen is designed and licensed to deliver exactly four weekly doses. No regulated UK pharmacy or prescriber can endorse it. Use the pen as designed, then dispose of it. If you want the full picture, read whether you can use what is left in your pen.

Ready for your next pen? You can order your next Mounjaro pen after a suitability check, and our weight loss clinic page explains the wider service.

03 · Pen won't dial

What if the pen won't dial to a full dose?

If the pen will not turn to a full dose, it has run out of full doses. Stop, do not inject a partial amount, and contact the pharmacy or your prescriber if you think a pen has delivered fewer than four doses.¹³ Our page on a pen that still has liquid in it covers this too.

04 · Storage and in-use pens

Storing your pen between doses

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 at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away. Do not use a pen that has been above 30°C or has been frozen. Keep the cap on to protect it from light.¹ A genuine UK Mounjaro pen comes from a registered pharmacy with a batch number and expiry date, arrives cold-chain packaged, and the solution inside is clear and colourless. Do not use a pen that has been frozen, looks cloudy or discoloured, has particles in it, or is past its expiry. Four weekly doses fit within that window, so you should not need to keep a pen beyond it.

For a fuller walkthrough see our complete guide to liquid left in the pen.