Before taking the potion, Juliet expresses the following fears:
- She fears that the potion might be poison and kill her.
- She worries that the potion might not work, and she will have to marry Paris.
- She worries that Friar Lawrence will tell her parents about their plan.
Note: While the option "She worries that Romeo no longer loves her" may capture a concern, it is not one of the primary fears she expresses about taking the potion in the context of her immediate situation before the act.