Mounjaro 5th dose: What the “Golden Dose” is and why you should never use leftover liquid

Mounjaro is a popular weight loss injection that contains the active ingredient tirzepatide. It works similarly to 2 hormones that are found in the body: glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).

By acting similarly to these hormones, Mounjaro slows down how quickly the stomach empties, tells the brain you’re full, and improves blood sugar control. This helps you to eat less and lose weight.

Mounjaro is given as a weekly injection using a KwikPen device. Each KwikPen is set to a certain dose and contains 4 injections of this dose. You will start at the lowest dose pen and move up to the next dose pen after at least 4 weeks.

The standard doses are 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg. But some people talk about the “5th dose” or “golden dose”.

The Mounjaro “5th” or “golden” dose refers to the liquid left in a Mounjaro KwikPen after you’ve administered 4 doses. Each pen is designed to give 4 doses of 0.6ml each. How much Mounjaro is contained in each dose depends on which dose pen you have.

A little extra of the Mounjaro-containing liquid is included in each pen. This ensures there’s enough liquid to prime the device before giving each dose. This extra liquid is not designed to be injected – it’s included as a safety measure to make sure the device can be used properly.

The Mounjaro “5th dose” is unsafe because it’s not designed to be given as a dose. As some liquid is lost every time you prime the KwikPen device, there is not always the same amount of liquid left after you’ve given yourself the standard 4 Mounjaro doses.

This means you do not know how much liquid you’re administering with the “golden dose”, which also means you do not know how much Mounjaro you’re getting.

If you’re using the “5th dose” to replace a standard Mounjaro dose, this may mean you’re getting a much smaller dose than you should be. This can interfere with your dosing schedule and may worsen side effects if you take the “5th dose” before stepping up to the next Mounjaro dose.

You may also take too much Mounjaro if you take the “golden dose” on top of your standard dose, which can also worsen side effects like feeling sick (nausea), being sick (vomiting), constipation, or diarrhoea.

Mounjaro should always be taken as described by the manufacturer in the patient information leaflet and user manual.

The manufacturer of the Mounjaro KwikPen, Eli Lilly, states that the device is a disposable multi-use pen that’s designed for just 4 fixed doses of 0.6ml.

After administering 4 doses, the pen should be safely disposed of in a sharps bin. You should not share the pen with other people, even if the pen needle is changed. This is the same regardless of which dose of Mounjaro is contained within the pen.

A small amount of medicine may remain in the pen after all doses have been correctly given. Do not try to use any remaining medicine.

This extra medication is included within the KwikPen to help you prime the device before use. Before you try to inject your standard dose of medication, you prime the device as follows:

Step 1

Wash your hands with soap and water.

Step 2

Pull the pen cap straight off. Inspect the pen and label. Do not use if:

• the medicine name or dose strength does not match your prescription
• the pen is expired (EXP) or looks damaged
• the medicine has been frozen, has particles, is cloudy, or is discoloured – Mounjaro should be colourless to slightly yellow

Step 3

Wipe the red inner seal with a swab.

Step 4

Select a new pen needle. Always use a new pen needle for each injection to help prevent infections and blocked needles.

Then, pull off the paper tab from the outer needle shield.

Step 5

Push the capped pen needle straight onto the pen and twist the pen needle on until it is tight.

Step 6

Pull off the outer needle shield and keep it, as this will be reused. Then, pull off the inner needle shield and put it in your household bin.

Step 7

Slowly turn the dose knob until you hear 2 clicks and the extended line is shown in the dose window. This is the prime position. It can be corrected by turning the dose knob in either direction until the prime position lines up with the dose indicator.

Step 8

Hold your pen with the needle pointing up. Tap the cartridge holder gently to collect air bubbles at the top.

Step 9

Release some medicine into the air by pushing the dose knob in until it stops, then slowly count to 5 while holding the dose knob. The icon must be shown in the dose window. Do not inject into your body.

Priming removes air from the cartridge and makes sure that your pen is working correctly. Your pen has been primed if a small amount of medicine comes out of the tip of the pen needle.

If you do not see medicine, repeat steps 7 to 9, no more than 2 additional times.

If you still do not see medicine, then change the pen needle and repeat steps 7 to 9, no more than 1 additional time.