Effects on those who consume melange are outlined below:
* Mind altering: it could awaken dormant parts of the human mind and encourage expanded sensory perceptions. In some humans (notably the Bene Gesserit, Guild Navigators, and some members of the Atreides bloodline), heavy doses led to powerful abilities that include prescience;
* Health benefits: taken regularly it increased life expectancy and fortified over all health levels (in many cases life expectancy was tripled);
* Addictiveness: the spice had narcotic properties, thus increasing demand and creating a large and hungry market for it. An individual's addiction to the spice would worsen the more they consumed it.
* Physical effects: sustained use of the spice led to human eyes being discolored so that the entire eye would be stained blue. Extensive exposure to the spice created a huge physical dependency that could radically alter the entire body (see Guild navigators).