The trend, which has gained significant traction across social media platforms including TikTok and Reddit, centers on the small amount of liquid that remains visible in a Mounjaro KwikPen after all four prescribed doses have been administered. Some patients have begun treating this residual liquid as a bonus injection, believing it offers extra weight loss benefit or helps stretch the cost of their prescription further.

Weight Medics clinicians say this practice is both a misunderstanding of how the medication pen is engineered and a genuine safety concern for patients attempting it without medical oversight.

"The liquid left in a Mounjaro pen after the fourth dose is a built in buffer, not a hidden extra dose," said a spokesperson for Weight Medics. "It exists purely to make sure patients receive four accurate, full strength injections, even allowing for small variations during administration. It was never designed to be measured, extracted, or injected separately, and doing so carries a real risk of inconsistent dosing."

According to Weight Medics, attempting to use this leftover volume can result in patients receiving either significantly more or significantly less medication than intended, since the residual amount is neither standardized nor accurately measurable using the pen itself. This inconsistency can increase the likelihood of side effects such as nausea and vomiting, or in some cases reduce the medication's effectiveness entirely.

The clinic notes that manufacturer guidance, including from Eli Lilly, supports disposing of the pen once the four labelled doses have been delivered, regardless of any liquid still visible inside.

Weight Medics has published a detailed explainer addressing the topic directly, breaking down what the Mounjaro Golden Dose (5th Dose) actually refers to, why the leftover liquid exists, and what patients should do instead of attempting to use it. The clinic is encouraging patients who have questions about their dosing schedule, pen usage, or overall treatment plan to consult their prescribing clinician rather than relying on advice circulating online.

"We understand why this trend has spread. People want to get the most out of every prescription, especially with rising costs of weight loss treatment," the spokesperson added. "But the safest and most effective path is always working with a clinician who can guide your dosing based on your actual response, not chasing extra liquid left in a pen."

As part of its mission to support safe, effective weight management, Weight Medics offers medically supervised prescribing for Mounjaro and other GLP1 based treatments, alongside regular check ins to track patient progress, adjust dosing appropriately, and address any concerns that arise during treatment.

Patients seeking accurate, clinically reviewed information on Mounjaro dosing, including the fifth dose topic, can visit the Weight Medics website for further guidance.

About Weight Medics

Weight Medics is a UK based provider of medically supervised weight loss treatment, offering personalized prescribing and ongoing clinical support for patients using GLP1 based medications such as Mounjaro. The clinic is committed to helping patients achieve safe, sustainable results through professional oversight rather than unverified online advice.

Media Contact

Weight Medics
Website: https://weightmedics.co.uk
Phone: 020 7760 7670