Experts have strongly advised you do not use Mounjaro's so-called 'golden dose'.
Weightloss jabs like Mounjaro are increasing in popularity and the US has seen a staggering 700 percent increase in GLP-1 (glucagon-like peptide-1) antagonist usage in the last four years in patients who do not have diabetes, a 2024 report found.
Mounjaro is one of these GLP-1 medications, which also activates GIP (glucose-dependent insulinotropic polypeptide) receptors in the body by regulating blood sugar levels.
The key part of the jab and its weight loss benefits is the fact it slows down how quickly food is digested, leaving you feeling fuller for longer.
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Each Mounjaro pen contains four doses of the medication, but people have noticed that some of it is still in the pen after taking their final shot.
What is the 'golden dose'?
Each Mounjaro pen contains 3ml of liquid, and each dose uses 0.6ml — just enough for four, accurate, pre-measured doses of Mounjaro. That leaves a small amount of liquid behind.
The leftover liquid is not a bonus dose (often referred to as a 'golden dose') however. It’s a deliberate overfill built into the pen to ensure complete delivery of each injection.
There are a series of risks that come with using this 'dose', Voy's Chief Medical Officer, Dr. Earim Chaudry has warned.
Underdosing
There is a risk that you may not take enough of your prescribed medication.
"This can quietly stall your progress," Dr. Chaudry told UNILAD. "These treatments aren’t just about training your appetite; they help recalibrate how your body responds to hunger and fullness. When doses are too low or inconsistent, that gets disrupted."
Warning signs that you may be underdosing include stalled or slower-than-expected weight loss despite following other recommendations, and increased hunger or cravings returning.
Dr. Chaudry added: "The medication may seem like it’s 'not working' even though the real issue is with the dosing. Ultimately this can lead to frustration, slower progress, and in some cases, stopping treatment altogether, continuing a cycle, we know patients are keen to escape."
Overdosing
While taking the extra bit of medication may seem like a clever workaround, Dr. Chaudry warned that it can actually be 'a risky and unsafe move'.
"These pens aren’t designed for precision beyond their intended use, and pulling extra medication this way isn’t sterile, accurate, or reliable," he explained.
Sharing what might happen if you overdose on Mounjaro, Dr. Chaudry said: "Overdosing can quickly lead to dangerous and unpleasant symptoms like severe nausea, vomiting, diarrhoea, and dehydration.
"In rare cases, it could even trigger serious complications like pancreatitis. These medications are carefully calibrated for your safety, so stepping outside the guidance isn’t just bending the rules, it’s putting your health on the line."
Using an unsterile or out-of-date pen
If a pen is unsterile or out-of-date it can lead to 'serious problems' — one danger being that the medication may have degraded over time meaning it's no longer affective.
"Even more concerning is that an expired or compromised pen can harbour bacteria, increasing the risk of infection at the injection site — or worse, a systemic infection that could become dangerous," Dr. Chaudry said.
"Watch out for warning signs like redness, swelling, or pus at the injection site, fever, or generalised illness symptoms, alongside a lack of effectiveness."
Niamh Shackleton