The best replacement for heroin is morphine.

The best alternatives to heroin are rated as following:
★★★★★  morphine
★★★★★  heroine
★★★★  oxycodone
★★★★  crack
★★★  oxycontin
★★★  opium
★★  cocaine
★★  dilaudid
★★  methadone
★  meth
★  fentanyl
★  black tar heroin
★  nicotine
★  roxy
★  oxy
★  opana
  methamphetamine
  suicide leftover crack
  crystal meth

Your alternative for heroin is not listed? Suggest!
Speaking about heroin, one probably shouldn't forget about fentanyl.

Other search terms related to heroin and their ratings are:
★★★★★ fentanyl
★★ suboxone
★ subutex
You have in mind a companion for heroin and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of heroin in all years. Click on graph for more.
heroin
morphine
heroine