In Because of Winn-Dixie, the Littmus Lozenges are a special, perhaps even a bit magical, candy that evokes feelings of sadness in the people who taste it. In chapter 17, Miss Franny Block, the librarian, gives Opal a bunch of these little candies after telling her about how her ancestor, Ol' Littmus W. Block, created them after surviving the horrors of the Civil War. Miss Franny says that sorrow is one of the ingredients of the candy. Opal spends the next few days sharing the lozenges with all her friends and learning more about them as a result.

At the beginning of chapter 18, Opal heads over to Gloria Dump's house and offers her one of the Littmus Lozenges. Gloria tells Opal that they taste sweet, but they also remind her of the feeling of people leaving her. Opal asks if the lozenge contains feelings of sorrow and Gloria agrees that it does. The reader has already learned that Gloria's past is full of mistakes. Her struggles with alcoholism were a large part of these mistakes. Her past behavior drove away many people in her life, and it seems that the Littmus Lozenge reminds her of the sorrow of those people leaving her.