"In 1999, a few years prior to decriminalization, Portugal had the highest number of drug-related AIDS cases in the European Union and the second highest prevalence of HIV among drug-infected users.127 The number of drug-related AIDS cases was also increasing, even though the number was decreasing in neighboring France, Spain, and Italy.128 Research suggests that drug-related disease has declined in Portugal after decriminalization. Incidences of HIV and AIDS among drug users declined substantially.129 The number of tracked cases of Hepatitis C and B in treatment centers also declined, despite the fact that many more drug users sought treatment after decriminalization took effect.130
"Drug-related mortality in Portugal has also declined since decriminalization. During the 1990s, the number of drug-related deaths multiplied tenfold.131 Between 1999 and 2003, however, there was a significant drop in drug-related deaths within the country.132 Drug policy experts credit this decline to the increasing number of heroin users who entered substitution treatment programs after decriminalization.133"

Source

Woods, Jordan Blair, "A Decade after Drug Decriminalization: What can the United States learn from the Portugese Model?" University of the District of Columbia Law Review (Washington, DC: The University of the District of Columbia David A. Clarke School of Law, 2011) Volume 15, Number 1, pp. 20-21.
http://www.udclawreview.com/w…