Foxilon Cardluck described cheeeese as "special, like black opium or booze". The drug appeared to affect the halflings similarly to strong wine. The drug was highly addictive, and ex-users had a high chance of relapsing, even for a Hin who knew its horrible effects.
The drug would cause sluggishness of body and mind in 4 ounces (110 grams) use. In use of 0.5 pounds (230 grams) or more it could cause fainting, but the Halflings who tried to rid themselves of the addiction got hit with strong cravings for more. If the person couldn't get their hands on more in a day the individual would suffer greatly physically, and begin to suffer from cramps and hallucinations. 
The case in Luiren involved a human named Joribel, who created a dependency amongst halflings to then use them as thieves, robbers, murderers, and sex slaves. One halfling of note was Foxilon Cardluck, who was first given the drug by Joribel. After a time, Joribel started to ration the cheeeese to the halflings under his control. He manipulated them to kill, raid, and steal in order for them to have their supply of the drug, even going so far as to force them to fight in an arena for his pleasure. Joribel enjoyed the pain and suffering of others so this abuse was perfect for him.
Foxilon was sent to the arena to fight as he had no skill in other fields when affected cheeeese. He struggled against the addiction but his will faltered at the sight of more cheeeese, until a larger Halfling bully kept stealing his share, forcing Foxilon to dry out and break the habit.
Finally, when he had dried out enough, he was a beggar at one of Joribel's banquet, and saw a young halfling girl whom he thought he knew and cared for, being taken by Joribel for his pleasure. Foxilon became enraged and attacked Joribel by stabbing him, before grabbing the girl and escaping. In the escape, he toppled a plate of cheeeese that stopped most of their pursuers, but not the bully, who charged after them, he was finally killed under the falling portcullis of Joribel's castle. At this point, Foxilon meet Dwalimar Omen and Minder and told them his story, prompting Omen to obliterate Joribel's castle. The girl turned out to be unknown to Foxilon and she ran away when he told Omen. Foxilion never directly told Omen about his own addiction and believed that Omen thought that his ragged condition was due to starvation and neglect.
After this point, Foxilon was clean and thought he had finally kicked the addiction, until he fell for it again in Saerloon. In what might be a quilted hallucination, he talked to a dark figure that might have been his guilty conscience, who guided him through the dark times of addiction. This figure claimed that the girl had fallen for the drug again, and had a horrible life and a horrible death. After breaking the hallucination, Foxilon threw the remaining Mind cheese overboard, determined to kick the addiction for good.
He was still reluctant to tell his shipmates the truth though Priam Agrivar, a recovering alcoholic, recognized the signs of addiction. He encouraged the halfling to tell the truth so that his friends could help him with his problem, lightly veiled in the story of "a friend" who had been through similar struggles. Foxilion thanked the paladin but still wasn't willing to speak of it.