Almost 10% of people using the HSE's Needle Exchange Programme are injecting an illegal fake tan product.
Health chiefs have confirmed there's been over 500 seizures of the banned drug in three years.
Figures for numbers of vials detained from January 2014 until December 2016:
2014: 10 vials
2015: 334 vials
2016: 202 vials
Melanotan is a drug that was developed in the 80s as a form of treatment for skin cancer.
It increases the production of melanin in the skin hence why it has become available online as a tanning product.
But it's a banned substance here with reported side effects including flu-like symptoms and high blood pressure.
Because it's taken intraveneously, there's also the risk of contracting diseases like HIV.
A study commissioned by the HSE shows primary users of needle exchange programmes are Heroin and Methadone users.
However 22% of people swapping needles for sterile ones are steroid users while almost one in ten are injecting Melanotan or Melanotan Two.
The Health Products Regulatory Authority strongly advises against buying either of these products.
"There is no guarantee as to the quality, safety or efficacy of these unauthorised medicines. In addition, the administration of these products by injection further increases the health risks. The public should be aware that it is not possible to obtain these products in any legitimate establishment or for it to be supplied legally through any online source."