Mounjaro golden dose: is a fifth dose safe?

The “golden dose” or “fifth dose” of Mounjaro, is what some people online refer to as the liquid that's left in a Mounjaro Pen after four doses. The pen is only contain four measured doses, so some people view this as a bonus dose.

Given the cost of these pens, some will try to extract the extra liquid to use it, since some will often remain even after you've taken all four doses correctly.²

However, the leftover liquid is not a dose that has been measured or intended for use. You should discard it with the pen.

Your Mounjaro pen contains liquid which needs to be primed before each injection, as well as the four prescribed doses. This allowance helps ensure that all four doses are delivered correctly.³

Priming is the step required before injecting. It removes air from the cartridge and also checks that the pen is working. Be sure to follow the priming steps in the instructions supplied with your pen.⁴

An updated version of the KwikPen now leaves less liquid after four doses than the original version. Both were designed to deliver the same four-dose supply.

No, you should not try to inject any liquid you see that's left after your fourth dose.² Instead, dispose of your Mounjaro pen safely after its last (fourth) dose.²

The liquid you can see through the cartridge is not a correct dose measurement, and the markings on the cartridge holder should not be used to judge a dose.

If you cannot turn the knob to the full-dose position, there may not be enough medicine for a complete injection.

If there is liquid left in your pen, this does not mean you missed an injection. If you're not sure whether a dose went in properly, check with your pharmacist or GP before you use more.²

Always follow the prescribed dosage. If you have questions about changing strength, chat to your GP.² Our Mounjaro dosing guide explains how to titrate your dosage up.

Using leftover liquid isn't part of your prescribed dose shcedule.

Adults usually start at 2.5mg once a week for four weeks, then increase to 5mg for the next four week. Further increases are only made if needed, and after at least four weeks on the current dose. You should not change your dose yourself.²

Feeling sick, vomiting and diarrhoea are more common during dose increases, but often ease over time. If side effects are troublesome or you're concerned about your progress, chat to your pharmacist or GP before adjusting your dose.¹

A 2.5mg KwikPen dose is 0.6ml of liquid.¹

The dose printed on your pen is measured in milligrams (mg). Millilitres (ml) describe the volume of liquid.

Use a new needle for every injection to help prevent infection and blocked needles. You should never share your pen, even if you change the needle. This is because sharing can pass on a serious infection.

Remove the needle after use and put it straight into a sharps container. Leaving it attached during storage can cause leaks, blockage or air to get into the pen. Replace the pen cap before storing it.⁴

If the pen looks damaged, don't use it. Ask your pharmacist or GP for help with any problems using the pen.⁴

Talk to your doctor immediately if you have injected more Mounjaro than prescribed.² Too much can cause low blood sugar and make you feel sick or be sick.²

Take a missed dose as soon as possible, or within 4 days. You should skip it if more than 4 days have passed.¹² Take your next dose on your usual day.

Do not double your dose to make up for a missed injection. Leave at least 3 days between doses.²

Discard your KwikPen after four doses or 30 days after first use, whichever comes first.²² During that period, an opened pen can be kept out of the fridge at no more than 30°C.¹

Do not put leftover medicine in household rubbish or pour it down a drain. Ask your pharmacist how to dispose of your pen.²

For more about using your pen, read our guide to Mounjaro injections and the patient information leaflet.